Interventions that improve adherence to antihypertensive medications in coronary heart disease patients: a systematic review

A systematic review is conducted to identify effective interventions that improved adherence to antihypertensive drugs among patients with coronary heart diseases (CHDs). Primary studies designed to measure interventions to improve adherence on antihypertensive drugs in patients with CHD were included. Three online databases, COCHRANE, EMBASE and MEDLINE, were searched for primary studies published in English from 2005 to 2019. Studies were screened independently for eligibility. Cochrane risk-of-bias tool and the Newcastle-Ottawa Scale were used for quality assessment of randomised controlled trials (RCTs) and non-randomised studies, respectively. Of the 2000 entries identified, seven articles, including one cross-sectional study and six RCTs, met the inclusion criteria and were reviewed. One of the articles evaluated two interventions, so eight interventions were evaluated in total. Quality of the included studies was generally high, with the cross-sectional study rated as having good quality under Newcastle-Ottawa Scale, while four and two RCTs were rated as having low and some risk of bias under Cochrane risk-of-bias tool, respectively. Six of the intervention programmes were considered effective. An intervention was considered effective if it is associated with a significant (p≤0.05) and non-trivial (Cohen's d≥0.2) improvement in compliance-related outcomes such as in terms of the Morisky 8-item Medication Adherence Scale. Medication education, disease education, health education, constant reminders and medications dispensed using blister packs were identified to be effective in improving patients' compliance to medications. The importance of the continuity of interventions was also established. It is recommended that health service institutions should provide continuous education programmes, daily reminders and regular follow-ups for their patients who have CHD. It is recommended that further research ought to be carried out by using only one intervention in each trial with a standardised outcome measure, or using factorial designs, so that further cost-effectiveness evaluation of each intervention can be carried out independently, leading to the formulation of a comprehensive, optimised intervention programme for patients with CHD taking antihypertensives.