Evaluation of the effectiveness of cytisine for the treatment of smoking cessation: a systematic review and meta-analysis

Smoking is a chronic disease that generates 8 million premature deaths annually globally. It is one of the main causes of years of life lost or years lived with disability and is considered worldwide the main cause of preventable death. Objectives: to review the efficacy and safety of cytisine for smoking cessation. An exhaustive search was carried. The methods were established prior to their implementation (PROSPERO ID: CRD42022296780). We identified 12 RCTs that met our inclusion criteria. We pooled the findings of five RCT which contributed to the primary analysis (cytisine versus placebo) covering 2134 patients, 1099 of whom took cytisine, and indicates that cytisine administered at the standard dosage, is an effective smoking cessation treatment increasing the chances of quitting compared to placebo (smoking cessation rate at longest follow-up: RR= 3.75, 95% CI 2.83 to 4.97; participants = 2134; I²= 18%; smoking cessation rate at least six months: RR= 3.80, 95% CI 2.82 to 5.11; participants = 1938; I²= 35%; low-quality evidence). We estimate an NNT of 6. Two trials compared the efficacy of cytisine versus NRT and the combination of both studies yields modest results in favour of cytisine. Three recent trials comparing cytisine versus varenicline. Pooling these data not demonstrated a clear benefit for cytisine compared with varenicline. Meta-analyses of all non-serious AEs in the cytisine group versus placebo groups yielded a RR of 1.24 (95% CI 1.11 to 1.39; participants = 5895; studies = 8; I² = 0%; high-quality evidence).