Five RCTs (n=2,138) were included in the review. The sample sizes ranged from 180 to 269 participants.
At 1 year, NRT was more effective in maintaining reduced consumption of 50% or more of baseline levels than placebo: 16% versus 9%. A modest effect size was also reported for abstinence: 8% for NRT versus 4% for placebo (OR 2.50, 95% confidence interval, CI: 1.69, 3.68). Adverse events were uncommon (reported in 2 studies) and were not significantly different for the two groups.
There was significant heterogeneity between studies reporting a reduction in consumption (I2=67%; p=0.02).