Association between adherence to free nicotine replacement therapy and successful quitting

Providing free nicotine replacement therapy (NRT) can be a cost-effective strategy for increasing quit attempts and cessation rates at a population level. However, the optimal amount of NRT to provide is unknown. Associations between duration of NRT use and abstinence may be overestimated as a result of reverse causality due to discontinuation following relapse. We examined the association between adherence to 10weeks of cost-free NRT and quit success at 6-month follow-up, after controlling for reverse causation by excluding participants who reported nonadherence due to relapse.

Individuals 18years or older who smoked at least 10 cigarettes daily and intended to quit within 30days received 10weeks of NRT at a smoking cessation workshop. There were 3922 participants who attended one of 114 workshops in 70 different localities in Ontario, Canada from 2007 to 2008.

At end of treatment participants were asked whether they had used "all" of the NRT (20%), "most" of it (28%), "some" of it (47%), or whether they "did not use any" of it (5%). After controlling for reverse causation and adjusting for potential confounding variables, poorer quit success was reported by those who used either some (AOR=0.43, 95% CI=0.26-0.69, p=0.001) or none (AOR=0.30, 95% CI=0.09-0.95, p=0.041) of the NRT versus all 10weeks. Post-estimation contrasts revealed using some versus most of the NRT was also associated with poorer quit success (p=0.026).

After controlling for reverse causation, adherence to 10weeks of cost-free NRT was associated with successful abstinence at six months post-treatment.