Downloaded from https://academic.oup.com/jnci/article-abstract/110/10/1141/4915402 by Ed 'DeepDyve' Gillespie user on 17 October 2018 JNCI J Natl Cancer Inst (2018) 110(10): djy025 doi: 10.1093/jnci/djy025 First published online February 28, 2018 Correspondence CORRESPONDENCE RE: Effectiveness of Pharmaceutical Smoking Cessation Aids in a Nationally Representative Cohort of American Smokers Saul Shiffman, Joe G. Gitchell See the Notes section for the full list of authors’ afﬁliations. Correspondence to: Saul Shiffman, PhD, Pinney Associates, 201 N. Craig Street (320), Pittsburgh, PA 15213 (e-mail: firstname.lastname@example.org). We read with interest Leas et al.’s analysis of the Current would likely produce contrary findings. To be clear, we believe Population Survey data (1) relating the use of pharmacotherapy that behavioral treatment is effective, including in combination to outcome in attempts to quit smoking, particularly as a de- with medication, and have long advocated its use (6). But Leas cade ago we published a similar analysis on some of the same et al.’s conclusion that medications that have been repeatedly data (2), not cited by Leas et al. We strongly agree with the edito- tested and found effective in randomized clinical trials do not rial by Tindle and Greevy that a major issue in the analysis is se- work without behavioral treatment is based on fatally con- rious confounding when treatment is assigned clinically or self- founded data. selected (3). This is a classic case of the well-known “confounding by indication” (4,5) (or by “severity”) problem, in Notes which treatment is primarily used by those who already have the most severe conditions and are the most prone to poor out- Affiliations of authors: Pinney Associates, Pittsburgh, PA (SS); comes. Leas et al. undertook heroic efforts to overcome con- University of Pittsburgh, Pittsburgh, PA (SS); Pinney Associates, founding by propensity score matching, but this is insufficient Bethesda, MD (JGG). to remove this bias. Those who are convinced they cannot suc- PinneyAssociates provides consulting services on tobacco ceed without treatment (and perhaps whose doctors are also so harm minimization (including nicotine replacement therapy convinced) are most likely to use it. The limited data available and vapor products) to Niconovum USA, RJ Reynolds Vapor in the survey cannot account for all the factors that may enter Company, and RAI Services Company, all subsidiaries of into smokers’ assessment of their own prognosis (eg, how moti- Reynolds American Inc. SS and JGG also hold a patent for a vated they are to quit, how difficult they found quitting last novel nicotine medication that has not been developed or time they tried, what impediments to quitting they expect, etc.). commercialized. When treatment is actively “assigned” by assessed of risk of failure, the resulting bias is near impossible to correct (5). References Indeed, such bias also affects the relationship between be- havioral treatment and outcome. Our 2008 analysis (2), which 1. Leas EC, Pierce JP, Benmarhnia T, et al. Effectiveness of pharmaceutical smok- ing cessation aids in a nationally representative cohort of American smokers. analyzed some of the same smokers as Leas et al., found that J Natl Cancer Inst. 2018;110(6):581–587. smokers who used behavioral treatment were statistically and 2. Shiffman S, Brockwell SE, Pillitteri JL, et al. Use of smoking-cessation treat- clinically significantly less likely to quit than those who did not. ments in the United States. Am J Prev Med. 2008;34(2):102–111. 3. Tindle HA, Greevy RA. Smoking cessation pharmacotherapy, even without And those who used both medication and behavioral treatment counseling, remains a cornerstone of treatment. J Natl Cancer Inst. 2018;110(6): did worst of all—worse than those who used only medication. 545–546. In other words, confounding by indication produces perverse 4. Miettinen OS. The need for randomization in the study of intended effects. Stat Med. 1983;2(2):267–271. and invalid “findings”—the more treatment, the worse the out- 5. Walker AM. Confounding by indication. Epidemiology. 1996;7(4):335–336. comes. Leas et al. argue that what is needed for medication to 6. Shiffman S, Paty JA, Rohay JM, et al. The efﬁcacy of computer-tailored smoking succeed is behavioral treatment. Yet they forego examining this cessation material as a supplement to nicotine polacrilex gum therapy. Arch premise directly in their analyses, where biasing by indication Intern Med. 2000;160(11):1675–1681. Received: January 8, 2018; Accepted: January 30, 2018 © The Author(s) 2018. Published by Oxford University Press. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/ licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact email@example.com CORRESPONDENCE
JNCI: Journal of the National Cancer Institute – Oxford University Press
Published: Oct 1, 2018
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