Nicotine replacement therapy: evidence from observational studies versus clinical trials

To the Editor: A “real world” study of smoking abstinence caught the attention of Australian media recently, who primarily focused on the commentary that “cold turkey” was the most successful approach for quitting smoking. Alpert and colleagues1 assessed the effects of nicotine replacement therapy (NRT) alone and/or in combination with behaviour counselling in 787 adult smokers from Massachusetts who had recently quit smoking.

The participation rates at baseline and waves 2 and 3 were 46%, 56% and 68%, respectively. At each follow-up, almost one-third of participants reported that they had relapsed. Relapse rates were similar, regardless of NRT participation. This contradicted the higher quit rates seen with groups given NRT compared with the placebo or control groups reported in meta-analyses.2-4 Among previously heavy smokers, the lowest relapse rate was in those who received NRT and counselling; and among previously light smokers, the relapse rate was the lowest among those who did not receive NRT or counselling. In both groups, those who received only NRT had the worst relapse rates, a finding which reinforces the importance of adjunct counselling.

Participants in the Alpert et al study1 self-reported NRT use. Quit status was not validated biochemically, which fails the Russell Standard5 of criteria applied to smoking cessation trials. Information on NRT dose, adherence, administration technique and reasons for shorter courses (eg, side effects, cost or perceived lack of benefit) were lacking. The longer term impact of NRT cannot be deduced from this study. The quality and quantity of psychological support received by each participant group was also unknown. It is unclear whether the study was adequately powered, given the small numbers of patients who completed a recommended course of NRT. Moreover, differential loss to follow-up threatens the study’s internal validity.

Multiple attempts are often necessary before a smoker can successfully quit. Repeated yearly access to courses of NRT, as allowed under the Pharmaceutical Benefits Scheme (a 12-week supply of patches is allowed each year for clients entering a comprehensive smoking cessation support program), may confer a benefit in the longer term. There is no evidence for the effectiveness of cold turkey cessation, especially in moderate to heavy smokers. Nevertheless, those determined to quit without pharmacotherapy or additional support should be encouraged to try cold turkey cessation.