Assessing adherence by combining the test of adherence to inhalers with pharmacy refill records

Background: The Global Initiative for Asthma (GINA) recommends the concurrent use of self-report and pharmacy refill data to assess treatment adherence. However, clinical evidence to support this combined approach is limited. Objective: To determine nonadherence to inhaler medication based on a validated questionnaire (Test of Adherence to Inhalers; TAI) and prescription refill data in a community sample of patients with chronic obstructive pulmonary disease (COPD) or asthma. Secondarily, we sought to determine the degree of concordance between these two measures. Methods: Cross-sectional, observational multicenter study in patients with asthma or COPD. Sociodemographic and clinical data were obtained from clinical records. Refill data were retrieved from electronic pharmacy databases. Participants completed the 12-item TAI during a single visit as part of routine care. Nonadherence was defined as TAI <50 or <80% pharmacy refill rate (PRR) in the previous 6 months. Results: A total of 816 patients (mean age, 60) were included. Nonadherence rates were 58.1% (TAI) and 28.6% (PRR) compared with 64.6% for the combined data (P<.0001). Concordance between the 2 measures was weak (k=0.205). Conclusions: These findings confirm the GINA recommendations, indicating that concomitant use of the TAI and pharmacy refill data identifies a higher percentage of nonadherent asthma or COPD patients than either instrument alone.