LAUSR

Introduction: Being in use for 50 years as a smoking cessation aid, cytisine initially lacked high-quality evidence, but recently the number of studies has increased with new clinical trials pending. The aim of this study was to compare data from earlier studies against newer studies completed within the last 10 years. Methods: We searched Pubmed, Embase and www.elibrary.ru for all studies on cytisine efficacy. After exclusion, nine randomized controlled trials dated from 1968 onwards were identified and included in the random effects meta-analysis of the continuous or longest reported abstinence, both self-reported and biochemically verified. We extracted relative risks (RR) from each study or, alternatively, calculated crude RRs from studies only reporting numbers of abstinent subjects. Results: Four studies (40%) were published in the last 10 years with the RR of continuous or longest abstinence ranging from 1.28 to 14.01. Recent studies with higher quality elucidated greater cytisine efficacy (abstinence RR 2.12 (95% confidence interval (CI) 1.27-3.54) than earlier studies (RR 1.54 (95% CI 1.23-1.93)). Heterogeneity between studies was high in both groups. Conclusions: Cytisine may be more effective in helping smokers stop than thought before. Cytisine may double the chance of successful cessation, but more studies with larger sample size are needed to confirm current data.