Article Text

Does smoking cessation result in improved mental health? A comparison of regression modelling and propensity score matching
  1. Gemma Taylor1,2,
  2. Alan Girling3,
  3. Ann McNeill2,4,
  4. Paul Aveyard2,5
  1. 1School of Health & Population Sciences, University of Birmingham, Birmingham, UK
  2. 2UK Centre for Tobacco and Alcohol Studies, Birmingham, UK
  3. 3School of Health & Population Sciences, University of Birmingham, Birmingham, UK
  4. 4Institute of Psychiatry, King's College London, London, UK
  5. 5Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK
  1. Correspondence to Dr Gemma Taylor; gmjtaylor{at}gmail.com

Abstract

Objectives Smokers report that smoking is therapeutic; a recent meta-analysis suggests the contrary. However, the association in that review may be explained by group-membership bias and confounding. Propensity score matching (PSM) aims to produce causal estimates from observational data. We examined the association between cessation and change in mental health before and after PSM.

Design A secondary analysis of prospective data from 5 placebo-controlled randomised trials for smoking reduction.

Participants All participants were adult smokers and had smoked for at least 3 years. Participants were excluded if they were pregnant, breast feeding, under psychiatric care, deemed to be unfit by a general practitioner or part of a cessation programme. In total, 937 participants provided smoking data at both 6-month and 12-month follow-ups. Of these, 68 were confirmed as abstinent at both 6 and 12 months and 589 as continuous smokers at both follow-ups.

Primary outcome Change in mental health (36-item Short Form Survey (SF-36), scored 0–100) from baseline (while all participants were smokers) to 12-month follow-up (after cessation) was compared between quitters and continuing smokers with and without adjustment, and after PSM.

Results Before matching, quitters’ mental health scores improved compared with continuing smokers’, the mean difference and 95% CI was 5.5 (1.6 to 9.4). After adjustment, the difference was 4.5 (0.6 to 8.5), and after PSM, the difference was 3.4 (−2.2 to 8.9).

Conclusions Improvements in mental health after smoking cessation may be partly but not completely explained by group membership bias and confounding.

  • PRIMARY CARE
  • PUBLIC HEALTH
  • MENTAL HEALTH
  • EPIDEMIOLOGY
  • SMOKING AND TOBACCO

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

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