Stages of change for adherence with medication regimens for chronic disease: Development and validation of a measure

Background: The stages-of-change (SOC) model has been used to explain and predict how behavior change occurs, but it is new as an approach to understanding why patients fail to take their medications as prescribed. Objective: This study validated a 2-item measure of SOC for adherence with medication regimens in 2 groups of patients prescribed pharmacologic therapy for chronic conditions. Methods: Two cross-sectional studies of attitudes toward medication adherence included the same measure of SOC for medication adherence. One was a sample of 161 HIV-positive patients in the United States, and the other was an international sample of 731 patients with hypertension. The validity of the measure of SOC for medication adherence was examined in both convenience samples using previously validated self-reported measures of adherence (the Medication Adherence Scale and a measure of adherence from the Medical Outcomes Study), and in the HIV sample using electronic monitoring of adherence behavior in 85 patients. Results: Construct validity was demonstrated in both samples by associations between SOC and the previously validated measures of adherence (P < 0.001), and predictive validity was supported by significant associations between SOC for medication adherence and electronically monitored medication-taking behavior during the next 30 days (P < 0.03). Conclusions: Behavior-change theory suggests that stage-tailored communication strategies are more effective than uniform health-promotion messages. Our results provide a foundation for the development of interventions for medication adherence that are tailored to patients' readiness for change. Our validated 2-item measure of SOC for medication adherence can be used to match communication strategies to individual motivation and readiness for adherence with chronic disease medication regimens.