Adherence to Varenicline in the COMPASS Smoking Cessation Intervention Trial

Patient adherence to smoking cessation medications can impact their effectiveness. It is important to understand the extent to which prescribed medications are actually taken by smokers, how this influences smoking cessation outcomes, and what factors may influence adherence.Smokers recruited from a large health plan were randomized to receive different modes of cessation counseling in combination with varenicline (Swan, G. E., McClure, J. B., Jack, L. M., Zbikowski, S. M., Javitz, H. S., Catz, S. L., et al. 2010.Behavioral counseling and varenicline treatment for smoking cessation. American Journal of Preventive Medicine, 38, 482-490). One thousand one hundred and sixty-one participants were mailed a 28-day varenicline supply when they set a quit date and were able to request up to two refills from the health plan pharmacy at no cost. Pharmacy fill records were obtained and telephone surveys completed at baseline, 21 days, 12 weeks, and 6 months post target quit date.Good adherence to varenicline (≥80% of days taken) was associated with a twofold increase in 6-month quit rates compared with poor adherence (52% vs. 25%). Smokers were more likely than nonsmokers to stop varenicline early. Purposeful nonadherence was associated with smoking at 12 weeks and was predicted in multivariate analyses by age, gender, adherence self-efficacy, and initial medication side effect severity.Innovative methods for increasing adherence to smoking cessation medications are needed, particularly early in the quit process. Simple metrics of adherence such as number of days cessation medication is taken can and should be routinely incorporated in effectiveness trials and reported to advance future attempts to understand and reduce nonadherence.