Improving adherence to treatment for hypertension

Abstract

BACKGROUND: Lack of adherence to blood pressure-lowering medication is a major reason for poor control of hypertension worldwide. Interventions to improve adherence to antihypertensive medication have been evaluated in randomized trials, but it is unclear which interventions are effective. OBJECTIVES: To determine the effectiveness of interventions aimed at increasing adherence to blood pressure-lowering medication in adults. SEARCH STRATEGY: The authors' performed an all-language search of all articles in the Cochrane Controlled Trials Register, MEDLINE, EMBASE, and CINAHL in April 2002. SELECTION CRITERIA: The authors selected randomized clinical trials (RCTs) of interventions to increase adherence to blood pressure-lowering medication in adults with essential hypertension, with adherence to medication and blood pressure control as outcomes. DATA COLLECTION AND ANALYSIS: Two authors extracted data independently and in duplicate and assessed each study according to the criteria outlined by the Cochrane Collaboration Handbook. PRIMARY RESULTS: The authors included 38 studies testing 58 different interventions and containing data on 15,519 patients. The studies were conducted in nine countries between 1975 and 2000. The duration of follow-up ranged from two to 60 months. Due to heterogeneity between studies in terms of interventions and the methods used to measure adherence, results were not pooled. Simplifying dosing regimens increased adherence in seven out of nine studies (relative increase in adherence, 8 to 19.6 percent). Motivational strategies were successful in 10 of 24 studies, with generally small increases in adherence, up to 23 percent. Complex interventions involving more than one technique increased adherence in eight out of 18 studies, ranging from 5 to 41 percent. Patient education alone seemed largely unsuccessful. REVIEWERS' CONCLUSIONS: Reducing the number of daily doses appears to be effective in increasing adherence to blood pressure-lowering medication and should be tried as a first-line strategy, although there is less evidence of an effect on blood pressure reduction. Some motivational strategies and complex interventions appear promising, but more evidence is needed from RCTs.