How can adherence to lipid-lowering medication be improved? A systematic review of randomized controlled trials.

OBJECTIVE Poor patient adherence to lipid-lowering medication is a major contributory factor in the lack of success in treating hyperlipidaemia. The objective of this review was to assess the effect of adherence-enhancing interventions for lipid-lowering medication. DESIGN Systematic review of randomized controlled trials (RCTs). DATA SOURCES Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, PsycInfo and CINAHL for all-language publications in November 2005. Direct contact with authors of included RCTs. METHODS Two reviewers extracted data independently and assessed studies according to criteria outlined by the Cochrane Reviewers' Handbook. RESULTS Nine RCTs were included in the review. Substantial between-study heterogeneity made pooling of data inappropriate. Four out of nine RCTs reported significantly improved adherence rates. The interventions associated with improved adherence were simplification of drug regimen (absolute increase 11%), patient information and education (13%) and intensified patient care (8.6% and 24%). Duration of follow-up was short, ranging from 2 to 24 months. No clear pattern emerged with regard to different classes of lipid-lowering drugs and adherence levels. CONCLUSIONS Intensified patient care appears to be the most promising intervention in terms of improved adherence to lipid-lowering drugs. Numbers of trials are low and evidence is sparse. Important aspects to be addressed in future studies are long-term follow-up, effect of improved adherence on serum lipid levels and concurrent, economic evaluation of adherence-enhancing strategies.