Predicting smoking abstinence with biological and self-report measures of adherence to varenicline: Impact on pharmacogenetic trial outcomes

Adherence based on salivary varenicline, rather than on pill counts, is predictive of Week 1 abstinence, irrespective of the biomarker of abstinence assessed, and of long-term abstinence. Direct measures of adherence enhance the ability to assess the impact of a biomarker or genetic marker on abstinence outcomes.