Background The standard way to stop smoking is to quit abruptly on a designated quit day. A number of smokers have tried unsuccessfully to quit this way. Reducing smoking before quitting could be an alternative approach to cessation. Before this method is adopted it is important to determine whether it is at least as successful as abrupt quitting. Objectives 1. To compare the success of reducing smoking to quit and abrupt quitting interventions. 2. To compare adverse events between arms in studies that used pharmacotherapy to aid reduction. Search strategy We searched the Cochrane Tobacco Addiction Review Group specialised register, MEDLINE, EMBASE and PsycInfo for topic specific terms combined with terms used to identify trials of tobacco addiction interventions. We also searched reference lists of relevant papers and contacted authors of ongoing trials. Date of most recent search: November 2009. Selection criteria We included randomized controlled trials (RCTs) that recruited adults who wanted to quit smoking. Studies included at least one condition which instructed participants to reduce their smoking and then quit and one condition which instructed participants to quit abruptly. Data collection and analysis The outcome measure was abstinence from smoking after at least six months follow-up. We pooled the included trials using a Mantel-Haenszel fixed-effect model. Trials were split for two sub-group analyses: pharmacotherapy vs no pharmacotherapy, self help therapy vs behavioural support. Adverse events were summarised as a narrative. It was not possible to compare them quantitatively as there was variation in the nature and depth of reporting across studies. Main results Ten studies were relevant for inclusion, with a total of 3760 participants included in the meta-analysis. Three of these studies used pharmacotherapy as part of the interventions. Five studies included behavioural support in the intervention, four included self-help therapy, and the remaining study had arms which included behavioural support and arms which included self-help therapy. Neither reduction or abrupt quitting had superior abstinence rates when all the studies were combined in the main analysis (RR= 0.94, 95% CI= 0.79 to 1.13), whether pharmacotherapy was used (RR= 0.87, 95% CI= 0.65 to 1.22), or not (RR= 0.97, 95% CI= 0.78 to 1.21), whether studies included behavioural support (RR= 0.87, 95% CI= 0.64 to 1.17) or self-help therapy (RR= 0.98, 95% CI= 0.78 to 1.23). We were unable to draw conclusions about the difference in adverse events between interventions, however recent studies suggest that pre-quit NRT does not increase adverse events. Authors' conclusions Reducing cigarettes smoked before quit day and quitting abruptly, with no prior reduction, produced comparable quit rates, therefore patients can be given the choice to quit in either of these ways. Reduction interventions can be carried out using self-help materials or aided by behavioural support, and can be carried out with the aid of pre-quit NRT. Further research needs to investigate which method of reduction before quitting is the most effective, and which categories of smokers benefit the most from each method, to inform future policy and intervention development.
