Level 2: Mid-level evidence
The efficacy of nicotine replacement therapy was evaluated in a systematic review of 12 placebo-controlled randomized trials that reported outcomes at one year (Tob Control. 2006;15:280-285). The reviewers did not state methods used for quality assessment or how they accounted for dropouts. Success was defined for each trial as the most conservative estimate of success, such as continuous abstinence rates with biochemical confirmation. The meta-analysis included 12 trials with 4,792 patients; trial duration ranged from two to eight years (weighted mean 4.3 years).
Replacement therapy included nicotine patch in five trials, nicotine gum in four trials, and nicotine nasal spray in three trials. Comparing nicotine replacement therapy vs. placebo, 12.2% vs. 7% of patients achieved long-term smoking cessation (P <.001, NNT 20) and 18.2% vs. 10.1% achieved smoking cessation at one year (NNT 13).