Electronic supplementary material
The online version of this article (doi:10.1186/s12889-015-2473-z) contains supplementary material, which is available to authorized users.
GT and AM have nothing to disclose; PA reports personal fees from Pfizer, grants and personal fees from McNeil, outside the submitted work.
GT was lead author for the manuscript and contributed towards study design, data analysis, reporting and interpretation of the findings. PA and AM contributed towards writing of the manuscript, study design, data analysis, reporting and interpretation of the findings. All authors reviewed the final manuscript.
It is possible that some people who quit smoking experience improved mental health after cessation and therefore remain abstinent, whereas other people who quit may experience worse mental health after cessation and therefore be more likely to relapse to smoking. Thus, in this study we aimed to examine the association between an enduring change in mental health following the cessation period and future risk of relapse.
A secondary analysis of prospective data pooled from five placebo-controlled randomised trials for smoking reduction conducted in Europe, USA and Australia. Change in mental health (SF-36, scored 0–100) was measured from baseline to four months for those who were biologically-validated as point-prevalence abstainers at four month follow-up. Thereafter we assessed whether relapse to smoking by 12 months was more likely in those whose mental health had worsened between baseline and four months compared with those who saw no change or an improvement.
After adjustment for baseline mental health and other major covariates, there was no greater tendency to relapse at 12 months for those whose mental health worsened after cessation compared with those who had no change or an improvement. The odds ratio and 95 % confidence interval was 1.01 (0.97 to 1.05).
People whose mental health worsens after smoking cessation are at no greater risk of subsequent relapse to smoking than those whose mental health stays the same or improves.