Medication adherence and apparent-treatment resistant hypertension: systematic review and meta-analysis

Abstract

Background: Medication non-adherence is a known behavioural contributor to poor blood pressure control that puts patients with apparent treatment-resistant hypertension (aTRH) at elevated cardiovascular risk. Studies of medication adherence for aTRH vary significantly with respect to design, methods, and setting; and as a result have produced highly variable figures describing the prevalence of non-adherence. This review aimed to elucidate the prevalence and potential moderators of medication non-adherence estimates for aTRH. Methods: A systematic literature search identified 26 studies that measured medication adherence for patients with uncontrolled blood pressure despite being prescribed three or more antihypertensive medications of different classes. Findings: Non-adherence rates ranged from 7.0 – 86.1%. The strongest contributor to variance in non-adherence rates was the method of adherence assessment used. Studies that relied on self-report measures of adherence and/or pharmacy data reported lower levels of non-adherence than studies using more objective methods, such as liquid chromatography–mass spectrometry in single time point bioassays or continuous electronic monitoring of medication taking. Discussion: Findings indicate that medication non-adherence is a significant problem among aTRH patients, and a major contributor to uncontrolled blood pressure at all healthcare levels. Identifying the most accurate and clinically feasible adherence assessment method is necessary to facilitate early intervention, reduce unnecessary prescribing of antihypertensive medications, and reduce the risk of adverse cardiovascular events for non-adherent aTRH patients.