Associations between self-reported adherence to antihypertensive medications and potential mechanisms of behavior change in a general outpatient sample

Aim: Adherence to antihypertensive medication is essential for positive outcomes among patients diagnosed with hypertension. Yet, up to 72% of individuals prescribed antihypertensives do not take medication as prescribed. Understanding mechanisms of behavior change (MoBCs) for antihypertensive adherence provides essential insight for how to change adherence behavior. This study examined the association between 4 potential MoBCs and self-reported antihypertensive adherence. Methods: This exploratory, cross-sectional study recruited 101 patients prescribed antihypertensive medications to complete self-report questionnaires on adherence and potential mechanisms of nonadherence. Antihypertensive adherence was assessed using the Hill-Bone Compliance to High Blood Pressure Therapy Scale (HB-HBP). The 4 putative MoBCs for nonadherence included self-efficacy, self-regulation, behavioral automaticity, and hypertension knowledge. Associations between self-reported antihypertensive adherence and MoBCs were examined using independent samples t-tests and multivariate median regression with covariate adjustment for participant characteristics. Results: The sample had a mean age of 61.7 years (SD = 13.1 years), was 59.4% female (n = 60), 66.3% White (n = 67), and 7.9% Hispanic (n = 8). Low adherence was reported by 16.8% of the study sample. Participants who reported low adherence to antihypertensive medications had lower scores on the self-efficacy questionnaire (p < 0.001) and hypertension knowledge (p = 0.045). Self-efficacy and hypertension knowledge remained significantly associated with self-reported adherence in multivariate regression with covariate adjustment. Conclusions: The current study supports the hypothesis that self-efficacy for adherence and additionally hypertension knowledge are the MoBCs most strongly associated with self-reported adherence behavior. Behavioral interventions to improve medication adherence should consider focusing on self-efficacy and hypertension knowledge as potentially important target MoBCs. The authors recommend that future research should consider tailored intervention approaches that target specific mechanisms of adherence and specific self-reported reasons for nonadherence.