Eight RCTs (n=565 participants) were included in the review. Sample size ranged from 10 to 298. One study reported methods of randomisation. Two RCTs described allocation concealment. Seven RCTs reported double-blinding but did not report methods. Seven RCTs reported use of ITT analyses.
Smoking abstinence: Greater abstinent rates were reported at trial end for: individual therapy together with NRT compared with usual care (RR 2.74, 95% CI 1.10 to 6.81; one RCT), bupropion together with group therapy compared with placebo with group therapy (RR 4.18, 95% CI 1.30 to 13.42; three RCTs), bupropion together with group therapy and NRT compared with placebo, group therapy and NRT (RR 2.34, 95% CI 1.12 to 4.91; two RCTs). None of these trials reported any significant differences between intervention and control groups at the end of follow-up. There were no significant differences between a specialised severe mental illness smoking programme with NRT compared with standard smoking cessation group therapy with NRT at either trial end or end of follow-up (one RCT).
Subgroup analyses reported that combined interventions that included bupropion significantly improved quit rates compared to placebo (RR 2.77, 95% CI 1.48 to 5.16; five RCTs).
There was no evidence of heterogeneity for these analyses (I2=0%).
Smoking Reduction: A significant increase in the number of participants who met criteria for smoking reduction was reported for individual therapy plus NRT compared with usual care at 13 months (RR 1.75, 95% CI 1.15 to 2.66; one RCT). Overall there were no significant differences between treatments for all other comparisons.
Adverse events: Five RCTs reported adverse events. One RCT reported no adverse events. One RCT reported three adverse events that required trial withdrawal (study arm not clearly identified). One RCT reported four withdrawals due to medication side effects. One RCT assessed toxicity and found no evidence. One RCT reported three serious adverse events that study authors deemed not to be related to study medication.