Estimating Demand and Cross-Price Elasticity for Very Low Nicotine Content (VLNC) Cigarettes Using a Simulated Demand Task

Estimating Demand and Cross-Price Elasticity for Very Low Nicotine Content (VLNC) Cigarettes... Abstract Introduction Very Low Nicotine Content (VLNC) cigarettes might be useful as part of a tobacco control strategy, but relatively little is known about their acceptability as substitutes for regular cigarettes. We compared subjective effects and demand for regular cigarettes and VLNC cigarettes, and estimated cross-price elasticity for VLNC cigarettes, using simulated demand tasks. Method Forty New Zealand smokers sampled a VLNC cigarette and completed Cigarette Purchase Tasks to indicate their demand for regular cigarettes and VLNC cigarettes at a range of prices, and a cross-price task indicating how many regular cigarettes and VLNC cigarettes they would purchase at 0.5x, 1x, and 2x the current market price for regular cigarettes, assuming the price of VLNC cigarettes remained constant. They also rated the subjective effects of the VLNC cigarette and their usual-brand regular cigarettes. Results Cross-price elasticity for VLNC cigarettes was estimated as 0.32 and was significantly positive, indicating that VLNC cigarettes are partially substitutable for regular cigarettes. VLNC cigarettes were rated as less satisfying and psychologically rewarding than regular cigarettes, but this was unrelated to demand or substitutability. Conclusion VLNC cigarettes are potentially substitutable for regular cigarettes. Their availability may reduce tobacco consumption, nicotine intake and addiction; making it easier for smokers to quit. Implications VLNC cigarettes share the behavioral and sensory components of smoking while delivering negligible levels of nicotine. Although smokers rated VLNCs as less satisfying than regular cigarettes, smokers said they would increase their consumption of VLNCs as the price of regular cigarettes increased, if VLNCs were available at a lower price. This suggests that VLNCs are partially substitutable for regular cigarettes. VLNCs can be part of an effective tobacco control strategy, by reducing nicotine dependence and improving health and financial outcomes for smokers. Introduction The reduction of nicotine in tobacco has been proposed as a means to reduce smoking dependence, behavior and negative health outcomes.1–3 One way to achieve this is to make Very Low Nicotine Content (VLNC) cigarettes—also known as “denicotinized” cigarettes—available. VLNC cigarettes contain tobacco with substantially less nicotine (<0.05 mg), and therefore deliver reduced levels of positively reinforcing effects that maintain smoking behavior. It is important to distinguish VLNC cigarettes from “low yield” or “light” cigarettes which generate lower yield of nicotine in machine testing due to features such as faster burn time or filter ventilation. Low yield cigarettes are prone to high rates of compensatory smoking which can lead to increased toxicant exposure and health risks.4,5 By contrast, VLNC cigarettes are associated with minimal levels or complete absence of compensatory smoking as measured by behavioral change and biomarker exposure relative to regular cigarettes.6–11 One way to determine whether VLNC cigarettes can be part of an effective tobacco control policy is to assess their potential as substitutes for regular cigarettes. Ideally, VLNC cigarettes would show comparable subjective favorability to regular cigarettes and similar demand characteristics with price. Subjective favorability may include ratings of quality, satisfaction, craving reduction, and withdrawal symptom reduction. Smokers tend to rate VLNC cigarettes as lower quality and less satisfying than their usual brand cigarettes.8,9,12,13 However in some cases these effects are minimal and it has been suggested that ratings may be affected by switching from a familiar brand to a novel research cigarette and unrelated to nicotine content.14 For example, Donny et al.9 found that switching from usual brand cigarettes to 0.3 mg and 0.05 mg cigarettes produced an immediate decrease in positive and increase in negative self-reported effects, regardless of nicotine content. Overall, smokers report that VLNC cigarettes reduce craving and withdrawal symptoms similarly to regular cigarettes,9,12 and similarly or better than some nicotine replacement products such as nicotine lozenges and patches.10,11,15 Because craving and withdrawal symptoms predict subsequent smoking behavior,16 this suggests that despite lower favorability, VLNC cigarettes may be helpful in reducing symptoms of nicotine withdrawal. Measuring demand and elasticity for VLNC cigarettes is another way of evaluating whether they may help to reduce nicotine intake when available independently or concurrently with regular cigarettes. Demand is the amount purchased at a given price, and elasticity is a measure of sensitivity of demand to changes in price.17 Several studies have used behavioral responses (eg, plunger pulls) as an analogue for price. For example, Shahan et al.14 found similar levels of demand and elasticity for regular and VLNC cigarettes when available independently. However when both were concurrently available at equal prices there was a strong preference for regular cigarettes. Johnson et al.18 examined cross-price elasticity (CPE) of VLNC cigarettes and nicotine gum. CPE is a measure of the relative change in demand for an alternative commodity available at a constant price given a change in the price of an original commodity. It is determined by calculating the slope of the relationship between consumption of the alternative and price of the original in log–log coordinates.19 VLNC cigarettes would be considered a substitute for regular cigarettes if they have a positive CPE, meaning their consumption would increase in response to increasing price of regular cigarettes. Johnson et al.18 found similar CPEs for VLNC cigarettes and nicotine gum when each was individually available with regular cigarettes (0.19 and 0.20 respectively) indicating that VLNCs are partially substitutable for regular cigarettes.19 This suggests that if the price of regular cigarettes were to increase by 10%, consumption of VLNC cigarettes would increase by 1.9%. An alternative approach for studying how consumption varies with price is to measure simulated demand in a Cigarette Purchase Task (CPT). In a CPT, smokers estimate how many cigarettes per day they would smoke at a range of hypothetical prices.20 This allows for relatively efficient data collection based on a broader range of prices than can be assessed in the natural economy or with behavioral analogues of price. The CPT has been used to generate simulated demand curves for regular cigarettes20–24 which conform to an exponential demand model.25 Although purchase tasks do not measure actual consumption, demand metrics derived from the CPT have demonstrated convergent and discriminant validity.20–23,26,27 Prior studies have found substantial overlap between choices for actual and hypothetical commodities,28–34 putatively due to the familiarity of the product (eg, cigarettes for daily smokers) and organization in discrete, well-understood units (eg, price in dollars and cigarettes individually or in packs).35 Hypothetical purchase tasks have been adapted for a wide range of commodities and can have important policy applications.36 The CPT has been used to evaluate the potential effects on bans on menthol flavoring by comparing demand curves for menthol and non-menthol cigarettes,37 and highlighting “left-digit effects” where transitions from one whole-number pack price to the next (eg, $4.80–$5.00) are associated with the largest proportionate decreases in cigarette consumption, and increases in motivation to attempt smoking cessation.35,38,39 CPE can also been assessed with a simulated demand procedure. Grace et al.40 asked smokers to estimate how many regular cigarettes and electronic cigarettes they would consume per day at three increasing prices for regular cigarettes with electronic cigarettes available at a constant, reduced price. CPE for electronic cigarettes was estimated as 0.16 and was significantly positive, indicating that if the price of regular cigarettes were to increase by 10%, consumption of electronic cigarettes would increase by 1.6%. VLNC cigarettes have the potential to enhance tobacco control efforts by acting as a substitute for regular cigarettes by reducing cravings and withdrawal symptoms, and reducing demand for regular cigarettes. However, it is important to consider how demand for VLNC cigarettes may differ if they are made available concurrently with regular cigarettes but at a discounted price, or if they are the only product available on the market, for example if there is a mandated reduction in nicotine across all brands. Thus in the present study we evaluated demand for VLNC cigarettes when available independently or concurrently with regular cigarettes. We use a CPT20 to obtain simulated demand curves for regular cigarettes and VLNC cigarettes, and also measured changes in simulated demand for VLNC and regular cigarettes when both were concurrently available.40 Method Participants Forty adult smokers were recruited by community and internet advertisement in Christchurch. They were required to be daily smokers, at least 18 years old, and not pregnant. Procedure Participants provided written informed consent. They completed online questionnaires and attended one laboratory session in which they sampled one VLNC cigarette (22nd Century Magic brand) and completed questionnaires about the favorability of the VLNC cigarettes and simulated demand for their own brand and the VLNC cigarettes. Participants were required to be abstinent from smoking for 12 hours prior to attending the session which was verified by measuring alveolar carbon monoxide (CO) with a CO monitor. All received a NZ $10 shopping mall voucher in return. The study was approved by the University of Canterbury Human Ethics Committee. Measures Online Questionnaires The online questionnaires included demographic information, smoking history, and two dependence measures. The Fagerstrom Test of Nicotine Dependence (FTND) assesses physical nicotine dependence based on the sum of 6 items scored from 0–3 or 0–1.41 Good test–retest reliability and internal consistency have been demonstrated (α = 0.64).42 The Glover–Nilsson Smoking Behaviour Questionnaire (GNSBQ) uses 18 items scored from 0–4 to assess the cognitive, social, and behavioral effects associated with tobacco dependence including associating smoking with daily activities and the use of tobacco to meet certain needs.43 It has good internal consistency (α = 0.82) and test–retest reliability (r = 0.86), and is significantly correlated with nicotine craving.44 Favorability Ratings Participants rated their usual brand and the VLNC cigarettes using the Modified Cigarette Evaluation Questionnaire (MCEQ)45; a 12-item questionnaire that assesses the reinforcing effects of smoking on three subscales including satisfaction, psychological reward and aversion, and two single items for enjoyment of respiratory tract sensations and craving reduction. It has good test–retest reliability on all subscales and single items, and the validity of the multidimensional framework was supported.46 Simulated Demand Tasks Participants completed two forms of the CPT, based on the CPT from MacKillop et al.20 for both their usual brand cigarette and the VLNC cigarette. Participants were asked to estimate their cigarette consumption on a typical day at escalating prices with their existing resources, no access to any other sources of tobacco and no stockpiling. The price range was broad to maximize the changes of attaining a breakpoint, including 20 prices from NZ $0 to NZ $25 per cigarette. The prices consisted of: NZ $0.2 increases from NZ $0 to NZ $2, NZ $1 increases from NZ $2 to NZ $5, NZ $2.50 increases from NZ $5 to NZ $20 and a NZ $5 increase from NZ $20 to NZ $25. Factory-made (FM) cigarette smokers were asked to estimate based on price per cigarette and administered the same price schedule as above, whereas roll-your-own (RYO) cigarette smokers were asked to estimate based on price per 30 g pouch. Current market price was in the same position on both scales (approximately NZ $0.80 per FM and NZ $40 per 30 g tobacco package for RYO) and changes in price relative to current market price were constant across both versions of the questionnaire. The CPT for the VLNC cigarettes asked participants to estimate based on price per cigarette regardless of whether they smoked FM or RYO cigarettes. Several analyses were conducted to characterize CPT demand curves. Measures were obtained directly from CPT responses and derived from fits of Koffarnus et al.’s47 exponentiated version of Hursh and Silberberg’s25 demand model47 using Microsoft Excel Solver. The equation for the exponentiated model is: Q=Q0 *10k(e−αQ0C−1) where Q is the demand at price C, Q0 is maximum consumption (ie, demand when cigarettes are free), k is a constant representing the span of the data in log10 units and α is elasticity, a fitted parameter which determines how quickly demand falls with increases in price (higher values of α indicate that demand falls more rapidly with price). Here, we determined k by subtracting the log10-transformed average consumption at the highest price from log10-transformed average consumption at the lowest price (giving k = 1.78). Essential Value (EV) is a definition of value based on sensitivity to price and is inversely proportional to α.48 The formula for EV is: EV=1/(100*α*k1.5) EV is linearly related to normalized Pmax, the price at which consumption is maximum. Pmax can be obtained from the observed data or calculated using the formula48: Pmax=m/(Q0*α*k1.5), where m=0.084k+0.65 Omax is the level of response output at Pmax, that is the maximum amount of money spent per day.Omax can be derived from normalized Pmax or obtained from the observed data. Participants completed an additional CPE simulated demand task in which they reported how many VLNC cigarettes and usual brand regular cigarettes they would purchase per day if they were concurrently available at escalating prices of regular cigarette while the price of VLNC cigarettes remained constant. The prices for regular cigarettes were intended to represent approximately 0.5x, 1x and 2x the current market price of cigarettes in New Zealand (NZ $0.40, NZ $0.80 and NZ $1.60), while the price of VLNCs was constant and subsidized (NZ $0.25). Results Participant Characteristics Participant characteristics are shown in Table 1. The average FTND score was 3.05 (SD = 1.95), with no significant differences by gender [t (38) = −0.63, p = .52], ethnicity [t(34) = −1.90, p = .07], or cigarette type usually smoked [t(38) = −1.70, p = .10]. The average level of behavioral dependence for the overall sample was 16.83 (SD = 5.32), which is in the moderate range. Behavioral dependence was significantly higher for females than males with means of 18.61 (SD = 4.74) and 14.84 (SD = 5.33) respectively [t(38) = −2.37, p < .05], but there were no significant differences by ethnicity [t(34) = 0.09, p = .93] or cigarette type usually smoked [t(38) = 0.18, p = .86]. Table 1. Participant Characteristics (N = 40) Demographic M SD Age 24.59 6.64 Gender % n Male 47.50 19 Female 52.50 21 Ethnicity New Zealand European 75 30 Non-European 22.5 9 Cigarette type usually smoked Factory-Made 57.50 23 Roll-Your-Own 42.50 17 Smoking dependence M SD FTND 3.05 1.95 GNSBQ 16.82 5.315 Demographic M SD Age 24.59 6.64 Gender % n Male 47.50 19 Female 52.50 21 Ethnicity New Zealand European 75 30 Non-European 22.5 9 Cigarette type usually smoked Factory-Made 57.50 23 Roll-Your-Own 42.50 17 Smoking dependence M SD FTND 3.05 1.95 GNSBQ 16.82 5.315 FTND = Fagerstrom Test of Nicotine Dependence; GNSBQ = Glover–Nilsson Smoking Behavior Questionnaire. View Large Table 1. Participant Characteristics (N = 40) Demographic M SD Age 24.59 6.64 Gender % n Male 47.50 19 Female 52.50 21 Ethnicity New Zealand European 75 30 Non-European 22.5 9 Cigarette type usually smoked Factory-Made 57.50 23 Roll-Your-Own 42.50 17 Smoking dependence M SD FTND 3.05 1.95 GNSBQ 16.82 5.315 Demographic M SD Age 24.59 6.64 Gender % n Male 47.50 19 Female 52.50 21 Ethnicity New Zealand European 75 30 Non-European 22.5 9 Cigarette type usually smoked Factory-Made 57.50 23 Roll-Your-Own 42.50 17 Smoking dependence M SD FTND 3.05 1.95 GNSBQ 16.82 5.315 FTND = Fagerstrom Test of Nicotine Dependence; GNSBQ = Glover–Nilsson Smoking Behavior Questionnaire. View Large Favorability Figure 1 shows the subjective favorability ratings based on the four subscales of the mCEQ separately for own brand cigarettes and VLNC cigarettes. Figure 1 shows that participants appeared to rate their own brand cigarettes more favorably than the VLNC cigarette on all four subscales. Participants rated VLNC cigarettes as 62% as satisfying as regular cigarettes (Ms = 2.66 and 4.28 respectively), 72% as rewarding as regular cigarettes (Ms = 2.81 and 3.92), 84% as aversive as regular cigarettes (Ms = 1.45 and 1.73), and 75% as effective in reducing craving (Ms = 3.73 and 5.00 respectively). A repeated-measures multivariate analysis of variance (MANOVA) was conducted with the four subscales (satisfaction, psychological reward, aversion and craving reduction) and cigarette type (own-brand vs. VLNC cigarette) as repeated-measures factor and gender as a between-groups factor. Significant multivariate effects were found for cigarette type [F(1,36) = 67.038, p < .001, Λ = 0.349], subscale [F(1,34) = 83.612, Λ = 0.119] and cigarette type × subscale [F(3,24) = 10.248, Λ = 0.525]. Post hoc testing (Tukey HSD) showed that own-brand cigarettes were rated higher than VLNC cigarettes for satisfaction, psychological reward, and craving reduction (p < .001), but there were no significant differences in aversion (p = .77). Figure 1. View largeDownload slide Mean ratings of own brand cigarettes (unfilled bars) and Very Low Nicotine Content (VLNC) cigarettes (filled bars) on the four mCEQ subscales: satisfaction, psychological reward, aversion and craving reduction. Asterisks indicated that regular cigarettes are rated significantly higher than VLNC cigarettes. Figure 1. View largeDownload slide Mean ratings of own brand cigarettes (unfilled bars) and Very Low Nicotine Content (VLNC) cigarettes (filled bars) on the four mCEQ subscales: satisfaction, psychological reward, aversion and craving reduction. Asterisks indicated that regular cigarettes are rated significantly higher than VLNC cigarettes. Simulated Demand Figure 2 shows demand for own brand and VLNC cigarettes (cigarettes/day) reported on the CPT. The results were characteristic of demand curves for inelastic commodities with cigarette consumption mostly high and decreasing sharply a relatively high prices, though demand for own brand cigarettes appears to be higher, especially at lower prices. The modified exponentiated model47 provided a good description of the average data for both own brand cigarettes and VLNC cigarettes, accounting for 94.1% and 95.1% of the variance, respectively. Fits to the individual data were more variable but the model still described results well, accounting for 89.7% of the data for own brand 88.9% for VLNC cigarettes (median values). Stein et al.’s49 algorithm was used to identify nonsystematic data. Four cases reported zero consumption of VLNC cigarettes at all prices for and thus did not meet the trend criterion. These cases were excluded from the demand curve analysis. Figure 2. View largeDownload slide Simulated demand for own brand cigarettes (filled diamonds) and Very Low Nicotine Content (VLNC) cigarettes (unfilled diamonds) using the Cigarette Purchase Task (CPT) plotted on logarithmic axes. The dashed lines indicate fits of the modified exponentiated model for each cigarette type. Figure 2. View largeDownload slide Simulated demand for own brand cigarettes (filled diamonds) and Very Low Nicotine Content (VLNC) cigarettes (unfilled diamonds) using the Cigarette Purchase Task (CPT) plotted on logarithmic axes. The dashed lines indicate fits of the modified exponentiated model for each cigarette type. A repeated-measures ANOVA found significant main effects of price [F(17,1292) = 103.299, p < .001, ƞp2 = 0.58] and cigarette type [F(1,76) = 12.272, p < .001, ƞp2 = 0.14], and a significant interaction between price and cigarette type [F(17,1292) = 5.003, p < .001, ƞp2 = 0.06]. Post hoc tests (Tukey HSD) revealed that from prices NZ $0 to NZ $1.20 there was significantly higher demand for own brand cigarettes than for VLNC cigarettes, however at prices of NZ $2 or higher there were no significant differences in demand for own brand or VLNC cigarettes. There was a significant interaction between cigarette type usually smoked (FM vs. RYO) and price [F(17,1292) = 4.196, p < .001, ƞp2 = 0.05] but no other significant interactions. Post hoc tests (Tukey HSD) revealed that RYO smokers reported higher demand for cigarettes at very low prices (NZ $0–NZ $0.20) than FM smokers, but no significant differences at prices NZ $0.40 or higher. Gender did not have a significant effect on demand [F(1,76) = 0.266, p = .61]. Prices of NZ $20 and NZ $25 per cigarette were excluded from the analysis as there was no variance; all participants reported zero consumption at these prices Table 2 shows means, results of repeated-measures ANOVAs and correlations for demand metrics derived from the CPT and the modified exponentiated model47 for own brand cigarettes and VLNC cigarettes. As anticipated, strong correlations were found between observed and derived Q0 (r = 0.99 for own brand cigarettes; r = 1.00 for VLNC cigarettes) and Omax (r = 0.94 for own brand cigarettes; r = 0.98 for VLNC cigarettes) scores. Repeated-measures ANOVAs confirmed that almost all demand metrics were significantly higher for own brand cigarettes than VLNC cigarettes including: EV [Ms = 0.418 and 0.253 respectively; F(1,31) = 7.719, p < .01, ƞp2 = 0.20], observed Q0 [Ms = 14.175 and 10.368; F(1,34) = 13.372, p < .001, ƞp2 = 0.27], derived Q0 [Ms = 16.306 and 11.345; F(1,36) = 13.647, p < .001, ƞp2 = 0.27], observed Omax [Ms = 12.960 and 7.640; F(1,31) = 11.011, p < .005, ƞp2 = 0.26], derived Omax [Ms = 10.365 and 6.260; F(1,31) = 67.719, p < .01, ƞp2 = 0.20], and BP [Ms = 4.703 and 2.747; F(1,36) = 6.545, p < .05, ƞp2 = 0.15]. There was no significant difference in Pmax [Ms = 2.620 and 1.894; F(1,31) = 3.412, p = .74] for the two cigarette types. A significant interaction was found between type of cigarette usually smoked and cigarette type sampled for BP [F(1,34) = 5.576, p < .05, ƞp2 = 0.15]. Post hoc analysis (Tukey HSD) revealed that FM smokers reported a higher breakpoint for their own brand cigarettes (M = 6.552) than RYO (M = 2.200), but there were no significant differences in breakpoints for VLNCs (Ms = 3.065 and 2.029). Additionally, FM smokers had significantly higher breakpoints for their own brand cigarettes (M = 6.552) than VLNC cigarettes (M = 3.065), but not RYO smokers (Ms = 2.2000 and 2.029). Table 2. Mean Scores and Correlation Coefficients for Measures of Demand Derived Directly From the CPT and From Fits of Koffarnus et al.’s47 Exponentiated Model Shown Separately for Own Brand and VLNC Cigarettes M (SD) Own brand 1. 2. 3. 4. 5. 6. 7. 1. EV 0.418 (0.291) — 2. Observed Q0 14.175 (9.719) 0.45* — 3. Derived Q0 16.306 (10.852) 0.48* 0.99* — 4. Observed Omax 12.960 (8.848) 0.94* 0.57* 0.60* — 5. Derived Omax 10.365 (7.214) 1.00* 0.45* 0.48* 0.94* — 6. Pmax 2.620 (1.844) 0.65* −0.22 −0.20 0.51* 0.65* — 7. Breakpoint 4.703 (4.429) 0.31* −0.13 −0.16 0.27 0.31* 0.46* — VLNC 1. 2. 3. 4. 5. 6. 7. 1. EV 0.253 (0.217)** — 2. Observed Q0 7.640 (5.440)*** 0.42* — 3. Derived Q0 6.260 (5.372)*** 0.46* 1.00* — 4. Observed Omax 12.955 (8.847)** 0.98* 0.50* 0.55* — 5. Derived Omax 10.368 (8.296)** 1.00* 0.42* 0.46* 0.98* — 6. Pmax 1.894 (1.434) 0.77* −0.13 −0.10 0.67* 0.778 — 7. Breakpoint 2.747 (2.583)* 0.49* 0.00 −0.02 0.40* 0.49* 0.58* — M (SD) Own brand 1. 2. 3. 4. 5. 6. 7. 1. EV 0.418 (0.291) — 2. Observed Q0 14.175 (9.719) 0.45* — 3. Derived Q0 16.306 (10.852) 0.48* 0.99* — 4. Observed Omax 12.960 (8.848) 0.94* 0.57* 0.60* — 5. Derived Omax 10.365 (7.214) 1.00* 0.45* 0.48* 0.94* — 6. Pmax 2.620 (1.844) 0.65* −0.22 −0.20 0.51* 0.65* — 7. Breakpoint 4.703 (4.429) 0.31* −0.13 −0.16 0.27 0.31* 0.46* — VLNC 1. 2. 3. 4. 5. 6. 7. 1. EV 0.253 (0.217)** — 2. Observed Q0 7.640 (5.440)*** 0.42* — 3. Derived Q0 6.260 (5.372)*** 0.46* 1.00* — 4. Observed Omax 12.955 (8.847)** 0.98* 0.50* 0.55* — 5. Derived Omax 10.368 (8.296)** 1.00* 0.42* 0.46* 0.98* — 6. Pmax 1.894 (1.434) 0.77* −0.13 −0.10 0.67* 0.778 — 7. Breakpoint 2.747 (2.583)* 0.49* 0.00 −0.02 0.40* 0.49* 0.58* — CPT = Cigarette Purchase Task; EV = Essential Value; SD = Standard deviation; VLNC = Very Low Nicotine Content. SD are listed in parentheses. Asterisks after VLNC cigarette demand scores indicate significant differences from own brand cigarette scores. Asterisks after means indicate significant differences. Differences in mean demand scores marked *** survive Bonferroni correction. Asterisks after correlation coefficients indicate significant relationships. *p < .05, **p < .01, ***p < .007. View Large Table 2. Mean Scores and Correlation Coefficients for Measures of Demand Derived Directly From the CPT and From Fits of Koffarnus et al.’s47 Exponentiated Model Shown Separately for Own Brand and VLNC Cigarettes M (SD) Own brand 1. 2. 3. 4. 5. 6. 7. 1. EV 0.418 (0.291) — 2. Observed Q0 14.175 (9.719) 0.45* — 3. Derived Q0 16.306 (10.852) 0.48* 0.99* — 4. Observed Omax 12.960 (8.848) 0.94* 0.57* 0.60* — 5. Derived Omax 10.365 (7.214) 1.00* 0.45* 0.48* 0.94* — 6. Pmax 2.620 (1.844) 0.65* −0.22 −0.20 0.51* 0.65* — 7. Breakpoint 4.703 (4.429) 0.31* −0.13 −0.16 0.27 0.31* 0.46* — VLNC 1. 2. 3. 4. 5. 6. 7. 1. EV 0.253 (0.217)** — 2. Observed Q0 7.640 (5.440)*** 0.42* — 3. Derived Q0 6.260 (5.372)*** 0.46* 1.00* — 4. Observed Omax 12.955 (8.847)** 0.98* 0.50* 0.55* — 5. Derived Omax 10.368 (8.296)** 1.00* 0.42* 0.46* 0.98* — 6. Pmax 1.894 (1.434) 0.77* −0.13 −0.10 0.67* 0.778 — 7. Breakpoint 2.747 (2.583)* 0.49* 0.00 −0.02 0.40* 0.49* 0.58* — M (SD) Own brand 1. 2. 3. 4. 5. 6. 7. 1. EV 0.418 (0.291) — 2. Observed Q0 14.175 (9.719) 0.45* — 3. Derived Q0 16.306 (10.852) 0.48* 0.99* — 4. Observed Omax 12.960 (8.848) 0.94* 0.57* 0.60* — 5. Derived Omax 10.365 (7.214) 1.00* 0.45* 0.48* 0.94* — 6. Pmax 2.620 (1.844) 0.65* −0.22 −0.20 0.51* 0.65* — 7. Breakpoint 4.703 (4.429) 0.31* −0.13 −0.16 0.27 0.31* 0.46* — VLNC 1. 2. 3. 4. 5. 6. 7. 1. EV 0.253 (0.217)** — 2. Observed Q0 7.640 (5.440)*** 0.42* — 3. Derived Q0 6.260 (5.372)*** 0.46* 1.00* — 4. Observed Omax 12.955 (8.847)** 0.98* 0.50* 0.55* — 5. Derived Omax 10.368 (8.296)** 1.00* 0.42* 0.46* 0.98* — 6. Pmax 1.894 (1.434) 0.77* −0.13 −0.10 0.67* 0.778 — 7. Breakpoint 2.747 (2.583)* 0.49* 0.00 −0.02 0.40* 0.49* 0.58* — CPT = Cigarette Purchase Task; EV = Essential Value; SD = Standard deviation; VLNC = Very Low Nicotine Content. SD are listed in parentheses. Asterisks after VLNC cigarette demand scores indicate significant differences from own brand cigarette scores. Asterisks after means indicate significant differences. Differences in mean demand scores marked *** survive Bonferroni correction. Asterisks after correlation coefficients indicate significant relationships. *p < .05, **p < .01, ***p < .007. View Large Figure 3 shows that demand for regular cigarettes decreased with increases in price, while demand for VLNC cigarettes (available at a constant, discounted price) increased. Cross-price elasticities (CPE) were calculated for individual participants as the regression slopes of (log) VLNC demand on (log) tobacco cigarette price. The mean CPE was 0.32 (95%CI = 0.578, 0.907) which was significantly greater than zero [t(39) = 2.886, p < .01, d = 0.92]. The positive value indicates that VLNC cigarettes are partially substitutable for regular cigarettes, such that if the price of regular cigarettes increased by 10%, consumption of VLNC cigarettes would increase by 3.2%. However, a positive CPE was only found for 25% of the sample, and the median CPE was 0. This indicates that, for the majority of the sample, demand for VLNC cigarettes did not increase with increasing price of regular cigarettes. Demand for regular cigarettes on the cross price task was 13.63% lower than average demand at the same three prices on the CPT (where only usual brand was available). Figure 3. View largeDownload slide Simulated demand for Very Low Nicotine Content (VLNC) cigarettes and regular cigarettes at three increasing prices of regular cigarettes while VLNC cigarettes are available at a constant discounted price. Error bars show 1SE. . Figure 3. View largeDownload slide Simulated demand for Very Low Nicotine Content (VLNC) cigarettes and regular cigarettes at three increasing prices of regular cigarettes while VLNC cigarettes are available at a constant discounted price. Error bars show 1SE. . Correlation analyses were conducted between smoking dependence scores (FTND and GNSBQ), the mCEQ subscales (reward, satisfaction, and craving reduction) for both own brand and VLNC cigarettes, demand metrics (EV, normalized Omax, normalized Pmax, derived Q0 and breakpoint) for both own brand and VLNC cigarettes, CPE and average demand for VLNC cigarettes across all three prices on the cross-price task. A summary of these analyses is included as Supplementary Table 1. Smoking dependence (FTND) was significantly positively associated with several demand metrics for own brand cigarettes (EV r = 0.58; normalized Omaxr = 0.58; normalized Pmaxr = 0.34, and derived Q0r = 0.57) and with Q0 for VLNC cigarettes (r = 0.43). However, smoking dependence (FTND) was significantly negatively correlated with satisfaction (r = −0.46), craving reduction (r = −0.37) for VLNC cigarettes. CPE was significantly positively associated with several demand metrics for VLNC cigarettes (EV r = 0.39; normalized Omaxr = 0.39; normalized Pmaxr = 0.42) but not with any VLNC mCEQ favorability subscales. Discussion VLNC cigarettes were rated as less satisfying and less psychologically rewarding than own-brand regular cigarettes, consistent with previous research.8,9,12,13 It has been suggested that negative responses to research cigarettes may be attributed to the fact that they are novel stimuli rather than the nicotine content per se.9 However in our study the participants sampled only one VLNC cigarette after a period of 12 hours abstinence, thus it is likely that nicotine withdrawal symptoms may have played a role. Although responses to the satisfaction subscale may have been more related to the novel nature of the cigarettes (items include enjoyment, satisfaction, and taste), the psychological reward subscale appears to be more related to the alleviation of nicotine withdrawal symptoms (items include feeling more calm, more awake, less irritable, improved concentration, and reduced hunger for food). As participants rated satisfaction and psychological reward at comparable levels for VLNC and regular cigarettes, the relative effects of the novel nature of the VLNC cigarette and the reduced nicotine content remain unclear. Participant also rated greater craving reductions for regular cigarettes than VLNC cigarettes, though both were rated highly. This is different from previous studies which have suggested that while participants rate VLNCs as less favorable than regular cigarettes, they reduce their craving, withdrawal symptoms, and smoking behavior at a similar rate.9–12,15 Aversion was rated very low for both regular and VLNC cigarettes suggesting that although VLNCs were rated less satisfying and rewarding than regular cigarettes, participants did not experience any aversive effects. Though they may have limited satisfying and rewarding properties, this was not correlated with demand or substitutability in this study. The demand curves produced by the CPT were similar for regular cigarettes and VLNC cigarettes, with patterns of decreasing demand with increasing price. Although demand for regular cigarettes was higher at relatively lower prices (up to $2 per cigarette), at higher prices there was no difference in demand for regular and VLNC cigarettes. At the other end of the scale, participants reported greater demand for regular cigarettes than VLNC cigarettes when the products were free. It is unclear why demand intensity is significantly lower for VLNC cigarettes. As they contain significantly less nicotine than regular cigarettes it would be anticipated that consumption would be higher in order to achieve optimal levels of reinforcement. This may suggest that preference and favorability are more important factors in determining consumption than optimal nicotine intake at lower, more affordable prices than at higher prices. However it is possible that the single use of the VLNCs may have been insufficient for participants to make informed choices on the CPT, and as such this design may not have supported an accurate assessment of demand and CPE. Nonetheless there may be important policy implications based on the demand data. The higher maximum amount of money spent per day (Omax) for regular cigarettes than VLNC cigarettes indicates that if VLNC cigarettes were available alongside regular cigarettes, even if at the same prices, smokers may reduce their expenditure on cigarettes. Breakpoint was also higher for regular cigarettes than VLNC cigarettes, indicating that smokers would quit at lower prices if VLNC cigarettes replaced regular cigarettes. These differences could have implications for low-income groups, for whom smoking prevalence is elevated.50 VLNCs may have the potential to reduce tobacco consumption and therefore expenditure, and may also mean that smokers would quit at lower prices which could have positive health and financial implications. The positive CPE (0.32) indicates that VLNCs are partially substitutable for regular cigarettes. This supports the utility of VLNC cigarettes, especially alongside the finding that on average demand for regular cigarettes was reduced by 13.63% with if VLNC cigarettes were available. Our VLNC CPE was slightly higher than the estimate obtained using behavioral procedures.18 It was also higher than the estimates generated for nicotine gum using behavioral procedures18,51 and regular electronic cigarettes using a simulated demand procedure.40 Reasons for this discrepancy are unclear. From a behavioral economic perspective, a reinforcer serves as a substitute because it shares a common function with the original reinforcer.19 It is possible that the behavioral, motor and sensory functions shared by regular cigarettes and VLNC cigarettes are more instrumental in smoking behavior than the shared function of nicotine withdrawal relief targeted by nicotine gum and regular electronic cigarettes. We found that higher nicotine dependence was associated with greater intensity of demand and more inelastic demand for regular cigarettes. These results were as expected and suggest that smokers that are more dependent on nicotine are less likely to change their smoking behavior in response to increases in the price of regular cigarettes. Greater dependence was also associated with lower satisfaction and craving reduction ratings for VLNC cigarettes. Again, this is to be expected as people with higher nicotine dependence are less likely to attain their optimal level of nicotine from the minimal levels available in VLNCs. It suggests that VLNC cigarettes may be less appealing for smokers that are more dependent on nicotine. Interestingly, CPE was associated with greater demand for VLNC cigarettes but was not associated with nicotine dependence, any demand indices for regular cigarettes or favorability ratings for either type of cigarettes. This suggests that the relatively negative favorability ratings of VLNCs did not impact how likely people would be to substitute them for regular cigarettes. Ratings of other perceptions and expectations of VLNC cigarettes may provide insight to what factors are associated with CPE, such as expected health benefits and their ability to help people quit smoking. Some limitations of the present study should be acknowledged. First, the sample size was relatively small, and several cases needed to be excluded from the VLNC analysis due to poor model fit. Second, we excluded four cases from the VLNC model fit where zero consumption was reported at all prices. It must be acknowledged that zero reported consumption is important information representing extremely low valuation of VLNCs for some individuals. As such the demand estimates for VLNC cigarettes may be somewhat inflated due to the exclusion of these cases. Third, it is not clear how accurately measures of simulated demand collected under controlled conditions correspond with actual behavior. However previous research suggests that choices in hypothetical purchase tasks correspond with actual behavior28–34 and our estimates of elasticity for VLNC cigarettes produced extremely good fits with the exponential model25 and were comparable with elasticity estimates for regular cigarettes in this study and in previous studies.20,23,52 Additionally, the predictive validity of elasticity derived from CPT data has been demonstrated following a tobacco excise tax increase23 which suggests that these procedures provide important information regarding the responsiveness of demand for VLNC cigarettes with changing price. Another limitation is the use of general price rather than unit price, that is, price per ml of nicotine. Unit price might help to clarify the mechanism underpinning differences in the demand curves and demand metrics for VLNC cigarettes; whether it is the significantly increased cost per mg of nicotine or non-nicotine factors. Finally, the CPE simulated demand task was comprised of a limited range and density of prices for tobacco cigarettes, and as such the CPE may not accurately estimate the shape of the function. Hursh and Roma48 propose an extension of the exponential equation for fitting CPE: QB=log(Qalone)+Ie−β*CA where Qalone is the level of demand for the constant-price commodity B (VLNC cigarettes) at infinite price (C) for commodity A (regular cigarettes), I is the interaction constant, β is the sensitivity of the commodity B to the price of commodity A and CA is the price of commodity A.48 This potentially provides a more accurate estimate of CPE but requires consumption to be a determined at a greater number of prices than the current study. However the prices we used (0.5x, 1x and 2x current market price) encompassed a relatively realistic range to obtain an estimate of the slope. The task has also been used in a previous study to obtain a CPE estimate for electronic cigarettes40,53 and yielded similar CPE estimates to those obtained in behavioral economic studies with nicotine gum and denicotinized cigarettes which used eight prices.18,51 We found similar demand curves and fits with the exponential model25 for regular and VLNC cigarettes which suggests that simulated demand procedures may be effectively used for alternative tobacco products. We also found similar, though slightly higher, CPE estimates to those generated using behavioral procedures using the simulated demand procedure.18,51,54 Although results should be interpreted cautiously, simulated demand procedures are a time- and cost-efficient way in which to generate quantitative and graphical estimates of demand, elasticity and CPE at a far wider range of prices than can be observed in the general market. There are multiple ways in which VLNC cigarettes may contribute to a nicotine reduction policy. One strategy would be to mandate that all cigarette brands gradually reduce their nicotine content to non-addictive levels (<0.05 mg). Another, likely more realistic, strategy would be to make VLNC cigarettes available at a lower prices than regular cigarettes. Our results suggest that VLNC cigarettes might serve as a more affordable substitute for regular cigarettes by increasing consumption of non-addictive cigarettes and reducing nicotine intake. It would be important to complement VLNCs with other evidence-based policies, such as continuing to increase the price of cigarettes, and considering the potential of novel approaches such as alternative nicotine delivery systems (eg, electronic cigarettes) also at relatively lower prices, as part of a comprehensive tobacco control strategy. Supplementary Material Supplementary data are available at Nicotine & Tobacco Research online. Funding This research was funded by the Tobacco Control Research Tūranga: A programme of innovative research to halve the smoking prevalence in Aotearoa/New Zealand within a decade. The Tūranga is supported through funding from the Reducing Tobacco-related Harm Research Partnership, co-funded by the Health Research Council of New Zealand and the Ministry of Health of New Zealand (HRC grant: 11/818). Decleration of Interests None declared. References 1. Benowitz NL Henningfield JE . Establishing a nicotine threshold for addiction. 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Shahan TA Odum AL Bickel WK . Nicotine gum as a substitute for cigarettes: a behavioral economic analysis . Behav Pharmacol . 2000 ; 11 ( 1 ): 71 – 79 . Google Scholar CrossRef Search ADS PubMed 52. Gallet CA List JA . Cigarette demand: a meta-analysis of elasticities . Health Econ . 2003 ; 12 ( 10 ): 821 – 835 . Google Scholar CrossRef Search ADS PubMed 53. Grace RC Kivell BM Laugesen M . Gender differences in satisfaction ratings for nicotine electronic cigarettes by first-time users . Addict Behav . 2015 ; 50 : 140 – 143 . Google Scholar CrossRef Search ADS PubMed 54. Johnson MW Bickel WK . The behavioral economics of cigarette smoking: the concurrent presence of a substitute and an independent reinforcer . Behav Pharmacol . 2003 ; 14 ( 2 ): 137 – 144 . Google Scholar CrossRef Search ADS PubMed © The Author(s) 2017. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Nicotine and Tobacco Research Oxford University Press

Estimating Demand and Cross-Price Elasticity for Very Low Nicotine Content (VLNC) Cigarettes Using a Simulated Demand Task

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Oxford University Press
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© The Author(s) 2017. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
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10.1093/ntr/ntx051
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Abstract

Abstract Introduction Very Low Nicotine Content (VLNC) cigarettes might be useful as part of a tobacco control strategy, but relatively little is known about their acceptability as substitutes for regular cigarettes. We compared subjective effects and demand for regular cigarettes and VLNC cigarettes, and estimated cross-price elasticity for VLNC cigarettes, using simulated demand tasks. Method Forty New Zealand smokers sampled a VLNC cigarette and completed Cigarette Purchase Tasks to indicate their demand for regular cigarettes and VLNC cigarettes at a range of prices, and a cross-price task indicating how many regular cigarettes and VLNC cigarettes they would purchase at 0.5x, 1x, and 2x the current market price for regular cigarettes, assuming the price of VLNC cigarettes remained constant. They also rated the subjective effects of the VLNC cigarette and their usual-brand regular cigarettes. Results Cross-price elasticity for VLNC cigarettes was estimated as 0.32 and was significantly positive, indicating that VLNC cigarettes are partially substitutable for regular cigarettes. VLNC cigarettes were rated as less satisfying and psychologically rewarding than regular cigarettes, but this was unrelated to demand or substitutability. Conclusion VLNC cigarettes are potentially substitutable for regular cigarettes. Their availability may reduce tobacco consumption, nicotine intake and addiction; making it easier for smokers to quit. Implications VLNC cigarettes share the behavioral and sensory components of smoking while delivering negligible levels of nicotine. Although smokers rated VLNCs as less satisfying than regular cigarettes, smokers said they would increase their consumption of VLNCs as the price of regular cigarettes increased, if VLNCs were available at a lower price. This suggests that VLNCs are partially substitutable for regular cigarettes. VLNCs can be part of an effective tobacco control strategy, by reducing nicotine dependence and improving health and financial outcomes for smokers. Introduction The reduction of nicotine in tobacco has been proposed as a means to reduce smoking dependence, behavior and negative health outcomes.1–3 One way to achieve this is to make Very Low Nicotine Content (VLNC) cigarettes—also known as “denicotinized” cigarettes—available. VLNC cigarettes contain tobacco with substantially less nicotine (<0.05 mg), and therefore deliver reduced levels of positively reinforcing effects that maintain smoking behavior. It is important to distinguish VLNC cigarettes from “low yield” or “light” cigarettes which generate lower yield of nicotine in machine testing due to features such as faster burn time or filter ventilation. Low yield cigarettes are prone to high rates of compensatory smoking which can lead to increased toxicant exposure and health risks.4,5 By contrast, VLNC cigarettes are associated with minimal levels or complete absence of compensatory smoking as measured by behavioral change and biomarker exposure relative to regular cigarettes.6–11 One way to determine whether VLNC cigarettes can be part of an effective tobacco control policy is to assess their potential as substitutes for regular cigarettes. Ideally, VLNC cigarettes would show comparable subjective favorability to regular cigarettes and similar demand characteristics with price. Subjective favorability may include ratings of quality, satisfaction, craving reduction, and withdrawal symptom reduction. Smokers tend to rate VLNC cigarettes as lower quality and less satisfying than their usual brand cigarettes.8,9,12,13 However in some cases these effects are minimal and it has been suggested that ratings may be affected by switching from a familiar brand to a novel research cigarette and unrelated to nicotine content.14 For example, Donny et al.9 found that switching from usual brand cigarettes to 0.3 mg and 0.05 mg cigarettes produced an immediate decrease in positive and increase in negative self-reported effects, regardless of nicotine content. Overall, smokers report that VLNC cigarettes reduce craving and withdrawal symptoms similarly to regular cigarettes,9,12 and similarly or better than some nicotine replacement products such as nicotine lozenges and patches.10,11,15 Because craving and withdrawal symptoms predict subsequent smoking behavior,16 this suggests that despite lower favorability, VLNC cigarettes may be helpful in reducing symptoms of nicotine withdrawal. Measuring demand and elasticity for VLNC cigarettes is another way of evaluating whether they may help to reduce nicotine intake when available independently or concurrently with regular cigarettes. Demand is the amount purchased at a given price, and elasticity is a measure of sensitivity of demand to changes in price.17 Several studies have used behavioral responses (eg, plunger pulls) as an analogue for price. For example, Shahan et al.14 found similar levels of demand and elasticity for regular and VLNC cigarettes when available independently. However when both were concurrently available at equal prices there was a strong preference for regular cigarettes. Johnson et al.18 examined cross-price elasticity (CPE) of VLNC cigarettes and nicotine gum. CPE is a measure of the relative change in demand for an alternative commodity available at a constant price given a change in the price of an original commodity. It is determined by calculating the slope of the relationship between consumption of the alternative and price of the original in log–log coordinates.19 VLNC cigarettes would be considered a substitute for regular cigarettes if they have a positive CPE, meaning their consumption would increase in response to increasing price of regular cigarettes. Johnson et al.18 found similar CPEs for VLNC cigarettes and nicotine gum when each was individually available with regular cigarettes (0.19 and 0.20 respectively) indicating that VLNCs are partially substitutable for regular cigarettes.19 This suggests that if the price of regular cigarettes were to increase by 10%, consumption of VLNC cigarettes would increase by 1.9%. An alternative approach for studying how consumption varies with price is to measure simulated demand in a Cigarette Purchase Task (CPT). In a CPT, smokers estimate how many cigarettes per day they would smoke at a range of hypothetical prices.20 This allows for relatively efficient data collection based on a broader range of prices than can be assessed in the natural economy or with behavioral analogues of price. The CPT has been used to generate simulated demand curves for regular cigarettes20–24 which conform to an exponential demand model.25 Although purchase tasks do not measure actual consumption, demand metrics derived from the CPT have demonstrated convergent and discriminant validity.20–23,26,27 Prior studies have found substantial overlap between choices for actual and hypothetical commodities,28–34 putatively due to the familiarity of the product (eg, cigarettes for daily smokers) and organization in discrete, well-understood units (eg, price in dollars and cigarettes individually or in packs).35 Hypothetical purchase tasks have been adapted for a wide range of commodities and can have important policy applications.36 The CPT has been used to evaluate the potential effects on bans on menthol flavoring by comparing demand curves for menthol and non-menthol cigarettes,37 and highlighting “left-digit effects” where transitions from one whole-number pack price to the next (eg, $4.80–$5.00) are associated with the largest proportionate decreases in cigarette consumption, and increases in motivation to attempt smoking cessation.35,38,39 CPE can also been assessed with a simulated demand procedure. Grace et al.40 asked smokers to estimate how many regular cigarettes and electronic cigarettes they would consume per day at three increasing prices for regular cigarettes with electronic cigarettes available at a constant, reduced price. CPE for electronic cigarettes was estimated as 0.16 and was significantly positive, indicating that if the price of regular cigarettes were to increase by 10%, consumption of electronic cigarettes would increase by 1.6%. VLNC cigarettes have the potential to enhance tobacco control efforts by acting as a substitute for regular cigarettes by reducing cravings and withdrawal symptoms, and reducing demand for regular cigarettes. However, it is important to consider how demand for VLNC cigarettes may differ if they are made available concurrently with regular cigarettes but at a discounted price, or if they are the only product available on the market, for example if there is a mandated reduction in nicotine across all brands. Thus in the present study we evaluated demand for VLNC cigarettes when available independently or concurrently with regular cigarettes. We use a CPT20 to obtain simulated demand curves for regular cigarettes and VLNC cigarettes, and also measured changes in simulated demand for VLNC and regular cigarettes when both were concurrently available.40 Method Participants Forty adult smokers were recruited by community and internet advertisement in Christchurch. They were required to be daily smokers, at least 18 years old, and not pregnant. Procedure Participants provided written informed consent. They completed online questionnaires and attended one laboratory session in which they sampled one VLNC cigarette (22nd Century Magic brand) and completed questionnaires about the favorability of the VLNC cigarettes and simulated demand for their own brand and the VLNC cigarettes. Participants were required to be abstinent from smoking for 12 hours prior to attending the session which was verified by measuring alveolar carbon monoxide (CO) with a CO monitor. All received a NZ $10 shopping mall voucher in return. The study was approved by the University of Canterbury Human Ethics Committee. Measures Online Questionnaires The online questionnaires included demographic information, smoking history, and two dependence measures. The Fagerstrom Test of Nicotine Dependence (FTND) assesses physical nicotine dependence based on the sum of 6 items scored from 0–3 or 0–1.41 Good test–retest reliability and internal consistency have been demonstrated (α = 0.64).42 The Glover–Nilsson Smoking Behaviour Questionnaire (GNSBQ) uses 18 items scored from 0–4 to assess the cognitive, social, and behavioral effects associated with tobacco dependence including associating smoking with daily activities and the use of tobacco to meet certain needs.43 It has good internal consistency (α = 0.82) and test–retest reliability (r = 0.86), and is significantly correlated with nicotine craving.44 Favorability Ratings Participants rated their usual brand and the VLNC cigarettes using the Modified Cigarette Evaluation Questionnaire (MCEQ)45; a 12-item questionnaire that assesses the reinforcing effects of smoking on three subscales including satisfaction, psychological reward and aversion, and two single items for enjoyment of respiratory tract sensations and craving reduction. It has good test–retest reliability on all subscales and single items, and the validity of the multidimensional framework was supported.46 Simulated Demand Tasks Participants completed two forms of the CPT, based on the CPT from MacKillop et al.20 for both their usual brand cigarette and the VLNC cigarette. Participants were asked to estimate their cigarette consumption on a typical day at escalating prices with their existing resources, no access to any other sources of tobacco and no stockpiling. The price range was broad to maximize the changes of attaining a breakpoint, including 20 prices from NZ $0 to NZ $25 per cigarette. The prices consisted of: NZ $0.2 increases from NZ $0 to NZ $2, NZ $1 increases from NZ $2 to NZ $5, NZ $2.50 increases from NZ $5 to NZ $20 and a NZ $5 increase from NZ $20 to NZ $25. Factory-made (FM) cigarette smokers were asked to estimate based on price per cigarette and administered the same price schedule as above, whereas roll-your-own (RYO) cigarette smokers were asked to estimate based on price per 30 g pouch. Current market price was in the same position on both scales (approximately NZ $0.80 per FM and NZ $40 per 30 g tobacco package for RYO) and changes in price relative to current market price were constant across both versions of the questionnaire. The CPT for the VLNC cigarettes asked participants to estimate based on price per cigarette regardless of whether they smoked FM or RYO cigarettes. Several analyses were conducted to characterize CPT demand curves. Measures were obtained directly from CPT responses and derived from fits of Koffarnus et al.’s47 exponentiated version of Hursh and Silberberg’s25 demand model47 using Microsoft Excel Solver. The equation for the exponentiated model is: Q=Q0 *10k(e−αQ0C−1) where Q is the demand at price C, Q0 is maximum consumption (ie, demand when cigarettes are free), k is a constant representing the span of the data in log10 units and α is elasticity, a fitted parameter which determines how quickly demand falls with increases in price (higher values of α indicate that demand falls more rapidly with price). Here, we determined k by subtracting the log10-transformed average consumption at the highest price from log10-transformed average consumption at the lowest price (giving k = 1.78). Essential Value (EV) is a definition of value based on sensitivity to price and is inversely proportional to α.48 The formula for EV is: EV=1/(100*α*k1.5) EV is linearly related to normalized Pmax, the price at which consumption is maximum. Pmax can be obtained from the observed data or calculated using the formula48: Pmax=m/(Q0*α*k1.5), where m=0.084k+0.65 Omax is the level of response output at Pmax, that is the maximum amount of money spent per day.Omax can be derived from normalized Pmax or obtained from the observed data. Participants completed an additional CPE simulated demand task in which they reported how many VLNC cigarettes and usual brand regular cigarettes they would purchase per day if they were concurrently available at escalating prices of regular cigarette while the price of VLNC cigarettes remained constant. The prices for regular cigarettes were intended to represent approximately 0.5x, 1x and 2x the current market price of cigarettes in New Zealand (NZ $0.40, NZ $0.80 and NZ $1.60), while the price of VLNCs was constant and subsidized (NZ $0.25). Results Participant Characteristics Participant characteristics are shown in Table 1. The average FTND score was 3.05 (SD = 1.95), with no significant differences by gender [t (38) = −0.63, p = .52], ethnicity [t(34) = −1.90, p = .07], or cigarette type usually smoked [t(38) = −1.70, p = .10]. The average level of behavioral dependence for the overall sample was 16.83 (SD = 5.32), which is in the moderate range. Behavioral dependence was significantly higher for females than males with means of 18.61 (SD = 4.74) and 14.84 (SD = 5.33) respectively [t(38) = −2.37, p < .05], but there were no significant differences by ethnicity [t(34) = 0.09, p = .93] or cigarette type usually smoked [t(38) = 0.18, p = .86]. Table 1. Participant Characteristics (N = 40) Demographic M SD Age 24.59 6.64 Gender % n Male 47.50 19 Female 52.50 21 Ethnicity New Zealand European 75 30 Non-European 22.5 9 Cigarette type usually smoked Factory-Made 57.50 23 Roll-Your-Own 42.50 17 Smoking dependence M SD FTND 3.05 1.95 GNSBQ 16.82 5.315 Demographic M SD Age 24.59 6.64 Gender % n Male 47.50 19 Female 52.50 21 Ethnicity New Zealand European 75 30 Non-European 22.5 9 Cigarette type usually smoked Factory-Made 57.50 23 Roll-Your-Own 42.50 17 Smoking dependence M SD FTND 3.05 1.95 GNSBQ 16.82 5.315 FTND = Fagerstrom Test of Nicotine Dependence; GNSBQ = Glover–Nilsson Smoking Behavior Questionnaire. View Large Table 1. Participant Characteristics (N = 40) Demographic M SD Age 24.59 6.64 Gender % n Male 47.50 19 Female 52.50 21 Ethnicity New Zealand European 75 30 Non-European 22.5 9 Cigarette type usually smoked Factory-Made 57.50 23 Roll-Your-Own 42.50 17 Smoking dependence M SD FTND 3.05 1.95 GNSBQ 16.82 5.315 Demographic M SD Age 24.59 6.64 Gender % n Male 47.50 19 Female 52.50 21 Ethnicity New Zealand European 75 30 Non-European 22.5 9 Cigarette type usually smoked Factory-Made 57.50 23 Roll-Your-Own 42.50 17 Smoking dependence M SD FTND 3.05 1.95 GNSBQ 16.82 5.315 FTND = Fagerstrom Test of Nicotine Dependence; GNSBQ = Glover–Nilsson Smoking Behavior Questionnaire. View Large Favorability Figure 1 shows the subjective favorability ratings based on the four subscales of the mCEQ separately for own brand cigarettes and VLNC cigarettes. Figure 1 shows that participants appeared to rate their own brand cigarettes more favorably than the VLNC cigarette on all four subscales. Participants rated VLNC cigarettes as 62% as satisfying as regular cigarettes (Ms = 2.66 and 4.28 respectively), 72% as rewarding as regular cigarettes (Ms = 2.81 and 3.92), 84% as aversive as regular cigarettes (Ms = 1.45 and 1.73), and 75% as effective in reducing craving (Ms = 3.73 and 5.00 respectively). A repeated-measures multivariate analysis of variance (MANOVA) was conducted with the four subscales (satisfaction, psychological reward, aversion and craving reduction) and cigarette type (own-brand vs. VLNC cigarette) as repeated-measures factor and gender as a between-groups factor. Significant multivariate effects were found for cigarette type [F(1,36) = 67.038, p < .001, Λ = 0.349], subscale [F(1,34) = 83.612, Λ = 0.119] and cigarette type × subscale [F(3,24) = 10.248, Λ = 0.525]. Post hoc testing (Tukey HSD) showed that own-brand cigarettes were rated higher than VLNC cigarettes for satisfaction, psychological reward, and craving reduction (p < .001), but there were no significant differences in aversion (p = .77). Figure 1. View largeDownload slide Mean ratings of own brand cigarettes (unfilled bars) and Very Low Nicotine Content (VLNC) cigarettes (filled bars) on the four mCEQ subscales: satisfaction, psychological reward, aversion and craving reduction. Asterisks indicated that regular cigarettes are rated significantly higher than VLNC cigarettes. Figure 1. View largeDownload slide Mean ratings of own brand cigarettes (unfilled bars) and Very Low Nicotine Content (VLNC) cigarettes (filled bars) on the four mCEQ subscales: satisfaction, psychological reward, aversion and craving reduction. Asterisks indicated that regular cigarettes are rated significantly higher than VLNC cigarettes. Simulated Demand Figure 2 shows demand for own brand and VLNC cigarettes (cigarettes/day) reported on the CPT. The results were characteristic of demand curves for inelastic commodities with cigarette consumption mostly high and decreasing sharply a relatively high prices, though demand for own brand cigarettes appears to be higher, especially at lower prices. The modified exponentiated model47 provided a good description of the average data for both own brand cigarettes and VLNC cigarettes, accounting for 94.1% and 95.1% of the variance, respectively. Fits to the individual data were more variable but the model still described results well, accounting for 89.7% of the data for own brand 88.9% for VLNC cigarettes (median values). Stein et al.’s49 algorithm was used to identify nonsystematic data. Four cases reported zero consumption of VLNC cigarettes at all prices for and thus did not meet the trend criterion. These cases were excluded from the demand curve analysis. Figure 2. View largeDownload slide Simulated demand for own brand cigarettes (filled diamonds) and Very Low Nicotine Content (VLNC) cigarettes (unfilled diamonds) using the Cigarette Purchase Task (CPT) plotted on logarithmic axes. The dashed lines indicate fits of the modified exponentiated model for each cigarette type. Figure 2. View largeDownload slide Simulated demand for own brand cigarettes (filled diamonds) and Very Low Nicotine Content (VLNC) cigarettes (unfilled diamonds) using the Cigarette Purchase Task (CPT) plotted on logarithmic axes. The dashed lines indicate fits of the modified exponentiated model for each cigarette type. A repeated-measures ANOVA found significant main effects of price [F(17,1292) = 103.299, p < .001, ƞp2 = 0.58] and cigarette type [F(1,76) = 12.272, p < .001, ƞp2 = 0.14], and a significant interaction between price and cigarette type [F(17,1292) = 5.003, p < .001, ƞp2 = 0.06]. Post hoc tests (Tukey HSD) revealed that from prices NZ $0 to NZ $1.20 there was significantly higher demand for own brand cigarettes than for VLNC cigarettes, however at prices of NZ $2 or higher there were no significant differences in demand for own brand or VLNC cigarettes. There was a significant interaction between cigarette type usually smoked (FM vs. RYO) and price [F(17,1292) = 4.196, p < .001, ƞp2 = 0.05] but no other significant interactions. Post hoc tests (Tukey HSD) revealed that RYO smokers reported higher demand for cigarettes at very low prices (NZ $0–NZ $0.20) than FM smokers, but no significant differences at prices NZ $0.40 or higher. Gender did not have a significant effect on demand [F(1,76) = 0.266, p = .61]. Prices of NZ $20 and NZ $25 per cigarette were excluded from the analysis as there was no variance; all participants reported zero consumption at these prices Table 2 shows means, results of repeated-measures ANOVAs and correlations for demand metrics derived from the CPT and the modified exponentiated model47 for own brand cigarettes and VLNC cigarettes. As anticipated, strong correlations were found between observed and derived Q0 (r = 0.99 for own brand cigarettes; r = 1.00 for VLNC cigarettes) and Omax (r = 0.94 for own brand cigarettes; r = 0.98 for VLNC cigarettes) scores. Repeated-measures ANOVAs confirmed that almost all demand metrics were significantly higher for own brand cigarettes than VLNC cigarettes including: EV [Ms = 0.418 and 0.253 respectively; F(1,31) = 7.719, p < .01, ƞp2 = 0.20], observed Q0 [Ms = 14.175 and 10.368; F(1,34) = 13.372, p < .001, ƞp2 = 0.27], derived Q0 [Ms = 16.306 and 11.345; F(1,36) = 13.647, p < .001, ƞp2 = 0.27], observed Omax [Ms = 12.960 and 7.640; F(1,31) = 11.011, p < .005, ƞp2 = 0.26], derived Omax [Ms = 10.365 and 6.260; F(1,31) = 67.719, p < .01, ƞp2 = 0.20], and BP [Ms = 4.703 and 2.747; F(1,36) = 6.545, p < .05, ƞp2 = 0.15]. There was no significant difference in Pmax [Ms = 2.620 and 1.894; F(1,31) = 3.412, p = .74] for the two cigarette types. A significant interaction was found between type of cigarette usually smoked and cigarette type sampled for BP [F(1,34) = 5.576, p < .05, ƞp2 = 0.15]. Post hoc analysis (Tukey HSD) revealed that FM smokers reported a higher breakpoint for their own brand cigarettes (M = 6.552) than RYO (M = 2.200), but there were no significant differences in breakpoints for VLNCs (Ms = 3.065 and 2.029). Additionally, FM smokers had significantly higher breakpoints for their own brand cigarettes (M = 6.552) than VLNC cigarettes (M = 3.065), but not RYO smokers (Ms = 2.2000 and 2.029). Table 2. Mean Scores and Correlation Coefficients for Measures of Demand Derived Directly From the CPT and From Fits of Koffarnus et al.’s47 Exponentiated Model Shown Separately for Own Brand and VLNC Cigarettes M (SD) Own brand 1. 2. 3. 4. 5. 6. 7. 1. EV 0.418 (0.291) — 2. Observed Q0 14.175 (9.719) 0.45* — 3. Derived Q0 16.306 (10.852) 0.48* 0.99* — 4. Observed Omax 12.960 (8.848) 0.94* 0.57* 0.60* — 5. Derived Omax 10.365 (7.214) 1.00* 0.45* 0.48* 0.94* — 6. Pmax 2.620 (1.844) 0.65* −0.22 −0.20 0.51* 0.65* — 7. Breakpoint 4.703 (4.429) 0.31* −0.13 −0.16 0.27 0.31* 0.46* — VLNC 1. 2. 3. 4. 5. 6. 7. 1. EV 0.253 (0.217)** — 2. Observed Q0 7.640 (5.440)*** 0.42* — 3. Derived Q0 6.260 (5.372)*** 0.46* 1.00* — 4. Observed Omax 12.955 (8.847)** 0.98* 0.50* 0.55* — 5. Derived Omax 10.368 (8.296)** 1.00* 0.42* 0.46* 0.98* — 6. Pmax 1.894 (1.434) 0.77* −0.13 −0.10 0.67* 0.778 — 7. Breakpoint 2.747 (2.583)* 0.49* 0.00 −0.02 0.40* 0.49* 0.58* — M (SD) Own brand 1. 2. 3. 4. 5. 6. 7. 1. EV 0.418 (0.291) — 2. Observed Q0 14.175 (9.719) 0.45* — 3. Derived Q0 16.306 (10.852) 0.48* 0.99* — 4. Observed Omax 12.960 (8.848) 0.94* 0.57* 0.60* — 5. Derived Omax 10.365 (7.214) 1.00* 0.45* 0.48* 0.94* — 6. Pmax 2.620 (1.844) 0.65* −0.22 −0.20 0.51* 0.65* — 7. Breakpoint 4.703 (4.429) 0.31* −0.13 −0.16 0.27 0.31* 0.46* — VLNC 1. 2. 3. 4. 5. 6. 7. 1. EV 0.253 (0.217)** — 2. Observed Q0 7.640 (5.440)*** 0.42* — 3. Derived Q0 6.260 (5.372)*** 0.46* 1.00* — 4. Observed Omax 12.955 (8.847)** 0.98* 0.50* 0.55* — 5. Derived Omax 10.368 (8.296)** 1.00* 0.42* 0.46* 0.98* — 6. Pmax 1.894 (1.434) 0.77* −0.13 −0.10 0.67* 0.778 — 7. Breakpoint 2.747 (2.583)* 0.49* 0.00 −0.02 0.40* 0.49* 0.58* — CPT = Cigarette Purchase Task; EV = Essential Value; SD = Standard deviation; VLNC = Very Low Nicotine Content. SD are listed in parentheses. Asterisks after VLNC cigarette demand scores indicate significant differences from own brand cigarette scores. Asterisks after means indicate significant differences. Differences in mean demand scores marked *** survive Bonferroni correction. Asterisks after correlation coefficients indicate significant relationships. *p < .05, **p < .01, ***p < .007. View Large Table 2. Mean Scores and Correlation Coefficients for Measures of Demand Derived Directly From the CPT and From Fits of Koffarnus et al.’s47 Exponentiated Model Shown Separately for Own Brand and VLNC Cigarettes M (SD) Own brand 1. 2. 3. 4. 5. 6. 7. 1. EV 0.418 (0.291) — 2. Observed Q0 14.175 (9.719) 0.45* — 3. Derived Q0 16.306 (10.852) 0.48* 0.99* — 4. Observed Omax 12.960 (8.848) 0.94* 0.57* 0.60* — 5. Derived Omax 10.365 (7.214) 1.00* 0.45* 0.48* 0.94* — 6. Pmax 2.620 (1.844) 0.65* −0.22 −0.20 0.51* 0.65* — 7. Breakpoint 4.703 (4.429) 0.31* −0.13 −0.16 0.27 0.31* 0.46* — VLNC 1. 2. 3. 4. 5. 6. 7. 1. EV 0.253 (0.217)** — 2. Observed Q0 7.640 (5.440)*** 0.42* — 3. Derived Q0 6.260 (5.372)*** 0.46* 1.00* — 4. Observed Omax 12.955 (8.847)** 0.98* 0.50* 0.55* — 5. Derived Omax 10.368 (8.296)** 1.00* 0.42* 0.46* 0.98* — 6. Pmax 1.894 (1.434) 0.77* −0.13 −0.10 0.67* 0.778 — 7. Breakpoint 2.747 (2.583)* 0.49* 0.00 −0.02 0.40* 0.49* 0.58* — M (SD) Own brand 1. 2. 3. 4. 5. 6. 7. 1. EV 0.418 (0.291) — 2. Observed Q0 14.175 (9.719) 0.45* — 3. Derived Q0 16.306 (10.852) 0.48* 0.99* — 4. Observed Omax 12.960 (8.848) 0.94* 0.57* 0.60* — 5. Derived Omax 10.365 (7.214) 1.00* 0.45* 0.48* 0.94* — 6. Pmax 2.620 (1.844) 0.65* −0.22 −0.20 0.51* 0.65* — 7. Breakpoint 4.703 (4.429) 0.31* −0.13 −0.16 0.27 0.31* 0.46* — VLNC 1. 2. 3. 4. 5. 6. 7. 1. EV 0.253 (0.217)** — 2. Observed Q0 7.640 (5.440)*** 0.42* — 3. Derived Q0 6.260 (5.372)*** 0.46* 1.00* — 4. Observed Omax 12.955 (8.847)** 0.98* 0.50* 0.55* — 5. Derived Omax 10.368 (8.296)** 1.00* 0.42* 0.46* 0.98* — 6. Pmax 1.894 (1.434) 0.77* −0.13 −0.10 0.67* 0.778 — 7. Breakpoint 2.747 (2.583)* 0.49* 0.00 −0.02 0.40* 0.49* 0.58* — CPT = Cigarette Purchase Task; EV = Essential Value; SD = Standard deviation; VLNC = Very Low Nicotine Content. SD are listed in parentheses. Asterisks after VLNC cigarette demand scores indicate significant differences from own brand cigarette scores. Asterisks after means indicate significant differences. Differences in mean demand scores marked *** survive Bonferroni correction. Asterisks after correlation coefficients indicate significant relationships. *p < .05, **p < .01, ***p < .007. View Large Figure 3 shows that demand for regular cigarettes decreased with increases in price, while demand for VLNC cigarettes (available at a constant, discounted price) increased. Cross-price elasticities (CPE) were calculated for individual participants as the regression slopes of (log) VLNC demand on (log) tobacco cigarette price. The mean CPE was 0.32 (95%CI = 0.578, 0.907) which was significantly greater than zero [t(39) = 2.886, p < .01, d = 0.92]. The positive value indicates that VLNC cigarettes are partially substitutable for regular cigarettes, such that if the price of regular cigarettes increased by 10%, consumption of VLNC cigarettes would increase by 3.2%. However, a positive CPE was only found for 25% of the sample, and the median CPE was 0. This indicates that, for the majority of the sample, demand for VLNC cigarettes did not increase with increasing price of regular cigarettes. Demand for regular cigarettes on the cross price task was 13.63% lower than average demand at the same three prices on the CPT (where only usual brand was available). Figure 3. View largeDownload slide Simulated demand for Very Low Nicotine Content (VLNC) cigarettes and regular cigarettes at three increasing prices of regular cigarettes while VLNC cigarettes are available at a constant discounted price. Error bars show 1SE. . Figure 3. View largeDownload slide Simulated demand for Very Low Nicotine Content (VLNC) cigarettes and regular cigarettes at three increasing prices of regular cigarettes while VLNC cigarettes are available at a constant discounted price. Error bars show 1SE. . Correlation analyses were conducted between smoking dependence scores (FTND and GNSBQ), the mCEQ subscales (reward, satisfaction, and craving reduction) for both own brand and VLNC cigarettes, demand metrics (EV, normalized Omax, normalized Pmax, derived Q0 and breakpoint) for both own brand and VLNC cigarettes, CPE and average demand for VLNC cigarettes across all three prices on the cross-price task. A summary of these analyses is included as Supplementary Table 1. Smoking dependence (FTND) was significantly positively associated with several demand metrics for own brand cigarettes (EV r = 0.58; normalized Omaxr = 0.58; normalized Pmaxr = 0.34, and derived Q0r = 0.57) and with Q0 for VLNC cigarettes (r = 0.43). However, smoking dependence (FTND) was significantly negatively correlated with satisfaction (r = −0.46), craving reduction (r = −0.37) for VLNC cigarettes. CPE was significantly positively associated with several demand metrics for VLNC cigarettes (EV r = 0.39; normalized Omaxr = 0.39; normalized Pmaxr = 0.42) but not with any VLNC mCEQ favorability subscales. Discussion VLNC cigarettes were rated as less satisfying and less psychologically rewarding than own-brand regular cigarettes, consistent with previous research.8,9,12,13 It has been suggested that negative responses to research cigarettes may be attributed to the fact that they are novel stimuli rather than the nicotine content per se.9 However in our study the participants sampled only one VLNC cigarette after a period of 12 hours abstinence, thus it is likely that nicotine withdrawal symptoms may have played a role. Although responses to the satisfaction subscale may have been more related to the novel nature of the cigarettes (items include enjoyment, satisfaction, and taste), the psychological reward subscale appears to be more related to the alleviation of nicotine withdrawal symptoms (items include feeling more calm, more awake, less irritable, improved concentration, and reduced hunger for food). As participants rated satisfaction and psychological reward at comparable levels for VLNC and regular cigarettes, the relative effects of the novel nature of the VLNC cigarette and the reduced nicotine content remain unclear. Participant also rated greater craving reductions for regular cigarettes than VLNC cigarettes, though both were rated highly. This is different from previous studies which have suggested that while participants rate VLNCs as less favorable than regular cigarettes, they reduce their craving, withdrawal symptoms, and smoking behavior at a similar rate.9–12,15 Aversion was rated very low for both regular and VLNC cigarettes suggesting that although VLNCs were rated less satisfying and rewarding than regular cigarettes, participants did not experience any aversive effects. Though they may have limited satisfying and rewarding properties, this was not correlated with demand or substitutability in this study. The demand curves produced by the CPT were similar for regular cigarettes and VLNC cigarettes, with patterns of decreasing demand with increasing price. Although demand for regular cigarettes was higher at relatively lower prices (up to $2 per cigarette), at higher prices there was no difference in demand for regular and VLNC cigarettes. At the other end of the scale, participants reported greater demand for regular cigarettes than VLNC cigarettes when the products were free. It is unclear why demand intensity is significantly lower for VLNC cigarettes. As they contain significantly less nicotine than regular cigarettes it would be anticipated that consumption would be higher in order to achieve optimal levels of reinforcement. This may suggest that preference and favorability are more important factors in determining consumption than optimal nicotine intake at lower, more affordable prices than at higher prices. However it is possible that the single use of the VLNCs may have been insufficient for participants to make informed choices on the CPT, and as such this design may not have supported an accurate assessment of demand and CPE. Nonetheless there may be important policy implications based on the demand data. The higher maximum amount of money spent per day (Omax) for regular cigarettes than VLNC cigarettes indicates that if VLNC cigarettes were available alongside regular cigarettes, even if at the same prices, smokers may reduce their expenditure on cigarettes. Breakpoint was also higher for regular cigarettes than VLNC cigarettes, indicating that smokers would quit at lower prices if VLNC cigarettes replaced regular cigarettes. These differences could have implications for low-income groups, for whom smoking prevalence is elevated.50 VLNCs may have the potential to reduce tobacco consumption and therefore expenditure, and may also mean that smokers would quit at lower prices which could have positive health and financial implications. The positive CPE (0.32) indicates that VLNCs are partially substitutable for regular cigarettes. This supports the utility of VLNC cigarettes, especially alongside the finding that on average demand for regular cigarettes was reduced by 13.63% with if VLNC cigarettes were available. Our VLNC CPE was slightly higher than the estimate obtained using behavioral procedures.18 It was also higher than the estimates generated for nicotine gum using behavioral procedures18,51 and regular electronic cigarettes using a simulated demand procedure.40 Reasons for this discrepancy are unclear. From a behavioral economic perspective, a reinforcer serves as a substitute because it shares a common function with the original reinforcer.19 It is possible that the behavioral, motor and sensory functions shared by regular cigarettes and VLNC cigarettes are more instrumental in smoking behavior than the shared function of nicotine withdrawal relief targeted by nicotine gum and regular electronic cigarettes. We found that higher nicotine dependence was associated with greater intensity of demand and more inelastic demand for regular cigarettes. These results were as expected and suggest that smokers that are more dependent on nicotine are less likely to change their smoking behavior in response to increases in the price of regular cigarettes. Greater dependence was also associated with lower satisfaction and craving reduction ratings for VLNC cigarettes. Again, this is to be expected as people with higher nicotine dependence are less likely to attain their optimal level of nicotine from the minimal levels available in VLNCs. It suggests that VLNC cigarettes may be less appealing for smokers that are more dependent on nicotine. Interestingly, CPE was associated with greater demand for VLNC cigarettes but was not associated with nicotine dependence, any demand indices for regular cigarettes or favorability ratings for either type of cigarettes. This suggests that the relatively negative favorability ratings of VLNCs did not impact how likely people would be to substitute them for regular cigarettes. Ratings of other perceptions and expectations of VLNC cigarettes may provide insight to what factors are associated with CPE, such as expected health benefits and their ability to help people quit smoking. Some limitations of the present study should be acknowledged. First, the sample size was relatively small, and several cases needed to be excluded from the VLNC analysis due to poor model fit. Second, we excluded four cases from the VLNC model fit where zero consumption was reported at all prices. It must be acknowledged that zero reported consumption is important information representing extremely low valuation of VLNCs for some individuals. As such the demand estimates for VLNC cigarettes may be somewhat inflated due to the exclusion of these cases. Third, it is not clear how accurately measures of simulated demand collected under controlled conditions correspond with actual behavior. However previous research suggests that choices in hypothetical purchase tasks correspond with actual behavior28–34 and our estimates of elasticity for VLNC cigarettes produced extremely good fits with the exponential model25 and were comparable with elasticity estimates for regular cigarettes in this study and in previous studies.20,23,52 Additionally, the predictive validity of elasticity derived from CPT data has been demonstrated following a tobacco excise tax increase23 which suggests that these procedures provide important information regarding the responsiveness of demand for VLNC cigarettes with changing price. Another limitation is the use of general price rather than unit price, that is, price per ml of nicotine. Unit price might help to clarify the mechanism underpinning differences in the demand curves and demand metrics for VLNC cigarettes; whether it is the significantly increased cost per mg of nicotine or non-nicotine factors. Finally, the CPE simulated demand task was comprised of a limited range and density of prices for tobacco cigarettes, and as such the CPE may not accurately estimate the shape of the function. Hursh and Roma48 propose an extension of the exponential equation for fitting CPE: QB=log(Qalone)+Ie−β*CA where Qalone is the level of demand for the constant-price commodity B (VLNC cigarettes) at infinite price (C) for commodity A (regular cigarettes), I is the interaction constant, β is the sensitivity of the commodity B to the price of commodity A and CA is the price of commodity A.48 This potentially provides a more accurate estimate of CPE but requires consumption to be a determined at a greater number of prices than the current study. However the prices we used (0.5x, 1x and 2x current market price) encompassed a relatively realistic range to obtain an estimate of the slope. The task has also been used in a previous study to obtain a CPE estimate for electronic cigarettes40,53 and yielded similar CPE estimates to those obtained in behavioral economic studies with nicotine gum and denicotinized cigarettes which used eight prices.18,51 We found similar demand curves and fits with the exponential model25 for regular and VLNC cigarettes which suggests that simulated demand procedures may be effectively used for alternative tobacco products. We also found similar, though slightly higher, CPE estimates to those generated using behavioral procedures using the simulated demand procedure.18,51,54 Although results should be interpreted cautiously, simulated demand procedures are a time- and cost-efficient way in which to generate quantitative and graphical estimates of demand, elasticity and CPE at a far wider range of prices than can be observed in the general market. There are multiple ways in which VLNC cigarettes may contribute to a nicotine reduction policy. One strategy would be to mandate that all cigarette brands gradually reduce their nicotine content to non-addictive levels (<0.05 mg). Another, likely more realistic, strategy would be to make VLNC cigarettes available at a lower prices than regular cigarettes. Our results suggest that VLNC cigarettes might serve as a more affordable substitute for regular cigarettes by increasing consumption of non-addictive cigarettes and reducing nicotine intake. It would be important to complement VLNCs with other evidence-based policies, such as continuing to increase the price of cigarettes, and considering the potential of novel approaches such as alternative nicotine delivery systems (eg, electronic cigarettes) also at relatively lower prices, as part of a comprehensive tobacco control strategy. Supplementary Material Supplementary data are available at Nicotine & Tobacco Research online. Funding This research was funded by the Tobacco Control Research Tūranga: A programme of innovative research to halve the smoking prevalence in Aotearoa/New Zealand within a decade. The Tūranga is supported through funding from the Reducing Tobacco-related Harm Research Partnership, co-funded by the Health Research Council of New Zealand and the Ministry of Health of New Zealand (HRC grant: 11/818). Decleration of Interests None declared. References 1. Benowitz NL Henningfield JE . Establishing a nicotine threshold for addiction. 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Nicotine and Tobacco ResearchOxford University Press

Published: Mar 3, 2017

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