The number of studies and participants included in this review were unclear, but it appears that there were 10 studies: 3 placebo-controlled trials, 6 uncontrolled studies and 1 study that included controlled and uncontrolled samples.
Placebo-controlled trials.
Three placebo-controlled studies were included in the meta analyses (number of participants unclear). It is unclear whether the follow-up periods related to single groups of participants. Tabex was associated with a statistically significant increase in abstinence compared with placebo for short-term outcomes (OR 1.93, 95% confidence interval, CI: 1.21, 3.06; 3 trials); there was evidence of statistically significant heterogeneity (I2=76.1; p=0.02). Tabex was also associated with a statistically significant increase in abstinence compared with placebo for outcomes at 3 to 6 months (OR 1.83, 95% CI: 1.12, 2.99; 2 trials); there was evidence of statistically significant heterogeneity (I2=75.1; p=0.04). One study evaluated long-term outcomes: Tabex was associated with a statistically significant increase in abstinence compared with placebo (OR 1.77, 95% CI: 1.29, 2.43).
Effect of films containing cytisine.
Studies that evaluated the effect of films containing cytisine on in-patients with cardiovascular disease and healthy smokers reported quit rates of 56% and 26.6%, respectively, after testing the films for 15 days. One study of healthy smokers reported an abstinence rate of 27.8% at the end of the study after treatment for 6 to 14 months. Studies of smokers followed up at 6 to 14 months reported abstinence rates of 37.1 to 50%.
Effect of Tabex.
Rates of abstinence from smoking in participants using Tabex ranged from 29 to 76% at the end of treatment and from 13.8 to 70% after 3 to 12 months.
Some adverse and toxic effects for cytisine-containing products were discussed. The authors reported that several adverse effects were slightly more frequent in patients using cytisine than placebo: weight gain, headache and heartburn.