The impact of fixed-dose combination versus free-equivalent combination therapies on adherence for hypertension: a meta-analysis

Nonadherence to antihypertensive medication is considered as a reason of inadequate control of blood pressure. This meta-analysis aimed to systemically evaluate the impact of fixed-dose combination (FDC) therapy on hypertensive medication adherence compared with free-equivalent combination therapies. Articles were retrieved from MEDLINE and Embase databases using a combination of terms fixed-dose combinations and adherence or compliance or persistence and hypertension or antihypertensive from January 2000 to June 2017 without any language restriction. A meta-analysis was performed to parallel compare the impact of FDC vs free-equivalent combination on medicine adherence or persistence. Studies were independently reviewed by two investigators. Data from eligible studies were extracted and a meta-analysis was performed using R version 3.1.0 software. A total of nine studies scored as six of nine to eight of nine for Newcastle-Ottawa rating with 62481 patients with hypertension were finally included for analysis. Results showed that the mean difference of medication adherence for FDC vs free-equivalent combination therapies was 14.92% (95% confidence interval, 7.38%-22.46%). Patients in FDC group were more likely to persist with their antihypertensive treatment, with a risk ratio of 1.84 (95% confidence interval, 1.00-3.39). This meta-analysis confirmed that FDC therapy, compared with free-equivalent combinations, was associated with better medication adherence or persistence for patients with hypertension. It can be reasonable for physicians, pharmacists, and policy makers to facilitate the use of FDCs for patients who need to take two or more antihypertensive drugs.