Calculation of Prevalence with Markov Models: Budget Impact Analysis of Thrombolysis for StrokeMar, Javier; Sainz-Ezkerra, María; Miranda-Serrano, Erika
doi: 10.1177/0272989X07312720pmid: 18349439
Objectives . The objective is to develop a method for calculating the prevalence of stroke based on Markov models and to apply it to the assessment of the budget impact analysis of thrombolytic treatment.Methods. A Markov model was used to reproduce the natural history of stroke. The first step was to run the model to build the sojourn matrix from the initial population vector. The second step was to ascertain the number of individuals in the origin of each annual cohort. Finally, prevalence figures were obtained, validated, and used to calculate the impact of treatment with thrombolysis in 10% of patients with stroke in the Basque Country as if thrombolysis had begun in 2000 and would continue to 2015.Results. Stroke prevalence rates per 100,000 for the entire population are 898 for men and 686 for women, with a combined rate of 774 for men and women. Rates for stroke-related disability are 358 per 100,000 for men, 275 for women, and 309 for men and women combined. If 10% of the stroke patients would have received thrombolytic treatment from 2000 to 2015, the number of disabled in 2015 would be reduced by 328, and the net savings for the Basque society (2,100,000 inhabitants) would be 1.7 million.Conclusions. The budget impact analysis of thrombolysis for stroke starting in 2000 shows a positive impact on the health budget because it saves costs after 2006 and produces a net benefit in health from the beginning of treatment.
Systematic Review: Health-State Utilities in Liver Disease: A Systematic ReviewMcLernon, David J.; Dillon, John; Donnan, Peter T.
doi: 10.1177/0272989X08315240pmid: 18424560
Objectives. Health-state utilities are essential for cost-utility analysis. Few estimates exist for liver disease in the literature. The authors' aim was to conduct a systematic review of health-state utilities in liver disease, to look at the variation of study designs used, and to pool utilities for some liver disease states.Methods.A search of MED-LINE, EMBASE, and CINAHL from 1966 to September 2006 was conducted including key words related to liver disease and utility measuring tools. Articles were included if health-state utility tools or expert opinion were used. Variance-weighted mean utility estimates were pooled using metaregression adjusting for disease state and utility assessment method.Results.Thirty studies measured utilities of liver diseases/disease states. Half of these estimated utilities for hepatitis viruses: hepatitis A (n = 1), hepatitis B (n = 4), and hepatitis C (n = 10). Others included liver transplant (n= 6) and chronic liver disease (n= 5) populations. Twelve utility methods were used throughout. The EQ-5D (n = 10) was most popular method, followed by visual analogue scale (n = 9), time tradeoff (n = 6), and standard gamble (n = 4). Respondents were patients (n= 16), an expert panel (n = 10), non—liver diseases adults ( n=2), patient and expert (n = 1), and patient and healthy adult (n = 1). Type of perspective included community (n=21), patient (n=4), and both (n = 5). The pooled mean estimates in hepatitis C with moderate disease, compensated cirrhosis, decompensated cirrhosis, and post—liver transplant using the EQ-5D were 0.75, 0.75, 0.67, and 0.71, respectively. The change in these utilities using different methods were -0.07 (visual analogue scale), -0.01 (health utilities index version 3), +0.04 (standard gamble), + 0.08 (health utilities index version 2), + 0.12 (time tradeoff), and + 0.15 (standard gamble—transformed visual analogue scale).Conclusions.The authors have created a valuable liver disease— based utility resource from which researchers and policy makers can easily view all available utility estimates from the literature. They have also estimated health-state utilities for major states of hepatitis C.
Quality Performance Measurement Using the Text of Electronic Medical RecordsPakhomov, Serguei; Bjornsen, Susan; Hanson, Penny; Smith, Steven
doi: 10.1177/0272989X08315253pmid: 18480037
Background. Annual foot examinations (FE) constitute a critical component of care for diabetes. Documented evidence of FE is central to quality-of-care reporting; however, manual abstraction of electronic medical records (EMR) is slow, expensive, and subject to error. The objective of this study was to test the hypothesis that text mining of the EMR results in ascertaining FE evidence with accuracy comparable to manual abstraction.Methods.The text of inpatient and outpatient clinical reports was searched with natural-language (NL) queries for evidence of neurological, vascular, and structural components of FE. A manual medical records audit was used for validation. The reference standard consisted of 3 independent sets used for development (n=200 ), validation (n=118), and reliability (n=80).Results.The reliability of manual auditing was 91% (95% confidence interval [CI]= 85—97) and was determined by comparing the results of an additional audit to the original audit using the records in the reliability set. The accuracy of the NL query requiring 1 of 3 FE components was 89% (95% CI=83—95). The accuracy of the query requiring any 2 of 3 components was 88% (95% CI=82—94). The accuracy of the query requiring all 3 components was 75% (95% CI= 68— 83).Conclusions.The free text of the EMR is a viable source of information necessary for quality of health care reporting on the evidence of FE for patients with diabetes. The low-cost methodology is scalable to monitoring large numbers of patients and can be used to streamline quality-of-care reporting.
When Is Diagnostic Testing Inappropriate or Irrational? Acceptable Regret ApproachHozo, Iztok; Djulbegovic, Benjamin
doi: 10.1177/0272989X08315249pmid: 18480041
The authors provide a new model within the framework of theories of bounded rationality for the observed physicians' behavior that their ordering of diagnostic tests may not be rational. Contrary to the prevailing thinking, the authors find that physicians do not act irrationally or inappropriately when they order diagnostic tests in usual clinical practice. When acceptable regret (i.e., regret that a decision maker finds tolerable upon making a wrong decision) is taken into account, the authors show that physicians tend to order diagnostic tests at a higher level of pretest probability of disease than predicted by expected utility theory. They also show why physicians tend to overtest when regret about erroneous decisions is extremely small. Finally, they explain variations in the practice of medicine. They demonstrate that in the same clinical situation, different decision makers might have different acceptable regret thresholds for withholding treatment, for ordering a diagnostic test, or for administering treatment. This in turn means that for some decision makers, the most rational strategy is to do nothing, whereas for others, it may be to order a diagnostic test, and still for others, choosing treatment may be the most rational course of action.
Willingness to Pay for a Cure in Patients with Chronic GoutKhanna, Dinesh; Ahmed, Mansoor; Yontz, Dustin; Ginsburg, Shaari S.; Tsevat, Joel
doi: 10.1177/0272989X08315252pmid: 18349436
Introduction. Gout is a chronic painful inflammatory arthritis. The authors interviewed patients with chronic stable gout to assess their hypothetical willingness to pay (WTP) to be cured of their gout.Patients and Methods.Patients with gout were asked how much money they would be willing to pay every month out of pocket or as a co-pay to cure their gout. To assess determinants of WTP amounts, the authors performed stepwise multivariable linear regression analysis, controlling for demographics, health status, and relative concern about gout.Results.Of the 78 patients, 70 (90%) were male, 54 (69%) were Caucasian, 21 (27%) were African American, and 32 (41%) had annual incomes < $25,000. The median WTP amount was $25 ($0, $75) per month, and the mean (s) was $52 ($74) per month (range, $0-$350); 23 (30%) patients were unwilling to pay any amount. Patients who rated their gout as their top health concern were willing to pay a median of $63 ($25, $100) per month. In multivariable analysis, gout as the top health concern, greater frequency of gouty attacks over the past 1 y, and younger age were significantly associated with WTP amounts (R2 =0:19 ).Conclusion.Many patients with chronic gout would be willing to pay money every month in perpetuity to be cured of their gout. Younger patients, patients whose main health concern is gout, and patients with frequent attacks are willing to pay the most.
Modeling the Incubation Period of Inhalational AnthraxWilkening, Dean A.
doi: 10.1177/0272989X08315245pmid: 18556642
Ever since the pioneering work of Philip Sartwell, the incubation period distribution for infectious diseases is most often modeled using a lognormal distribution. Theoretical models based on underlying disease mechanisms in the host are less well developed. This article modifies a theoretical model originally developed by Brookmeyer and others for the inhalational anthrax incubation period distribution in humans by using a more accurate distribution to represent the in vivo bacterial growth phase and by extending the model to represent the time from exposure to death, thereby allowing the model to be fit to nonhuman primate time-to-death data. The resulting incubation period distribution and the dose dependence of the median incubation period are in good agreement with human data from the 1979 accidental atmospheric anthrax release in Sverdlovsk, Russia, and limited nonhuman primate data. The median incubation period for the Sverdlovsk victims is 9.05 (95% confidence interval = 8.0-10.3) days, shorter than previous estimates, and it is predicted to drop to less than 2.5 days at doses above 106spores. The incubation period distribution is important because the left tail determines the time at which clinical diagnosis or syndromic surveillance systems might first detect an anthrax outbreak based on early symptomatic cases, the entire distribution determines the efficacy of medical intervention—which is determined by the speed of the prophylaxis campaign relative to the incubation period—and the right tail of the distribution influences the recommended duration for antibiotic treatment.