Thirteen studies were included in the review: eight randomised controlled trials (RCTs, n=505 participants), one non-randomised controlled trial (n=79) and four single-group studies (n=105). Five of the RCTs were double-blind. Sample sizes ranged from eight to 180. Follow-up ranged from one to four months.
Nicotine replacement therapy (NRT): There were five studies: three single-group (pre-post test) studies and two controlled trials. All three single-group studies used NRT in conjunction with a psychosocial intervention. Abstinence rates post treatment were small (range 12% to 22%). One study that compared NRT with treatment as usual (stated in two tables as treatment as usual and in text as placebo) found a large effect size (ES) at one month follow-up (ES=1.0). A second study that compared NRT combined with contingency management versus contingency management alone found a small effect size of 0.08 post treatment and 0.12 at three months follow-up (confidence intervals not reported).
Psychosocial interventions: There were three controlled trials. One study found no difference post treatment between Freedom From Smoking and motivational enhancement treatment (ES=0). However, at four months follow-up Freedom From Smoking had a large effect compared with motivational enhancement therapy (ES=0.59). In a second study, eight weeks of Freedom From Smoking was found to have a small effect post intervention (ES=0.21) and a large effect at four months follow-up (ES=0.56) when compared with four weeks of Freedom From Smoking. A third study found a large effect with contingency management versus treatment as usual post intervention (ES=0.73) and at three months follow-up (ES=0.73) when abstinence was measured with carbon monoxide exhalation. Effect sizes were reported to be much lower when cotinine results were used to calculate effect sizes (effect sizes not reported).
Bupropion: There was one single-group pre-post test study and five placebo controlled studies. In all six studies, bupropion was co-administered with a psychosocial intervention. In the single group study (n=8), only one participant was abstinent at 21 weeks post baseline. The effect size for bupropion compared with placebo post intervention was large (ES range 0.62 to 0.83). At three months follow-up the effect size for bupropion compared with placebo varied from no effect to large effect (ES=0 to 0.77).