Interventions to improve adherence to lipid lowering medication.

Background: Lipid lowering drugs are still widely underused, despite compelling evidence about their effectiveness in the treatment and prevention of cardiovascular disease. Poor patient adherence to a medication regimen is a major factor in the lack of success in treating hyperlipidaemia. In this updated review we focus on interventions which encourage patients at risk of heart disease or stroke to take lipid lowering medication regularly.

Objectives: To assess the effects of interventions aimed at improved adherence to lipid lowering drugs, focusing on measures of adherence and clinical outcomes.

Search Strategy: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2008, Issue 1), MEDLINE, EMBASE, PsycINFO and CINAHL (March 2008). No language restrictions were applied.

Selection Criteria: Randomised controlled trials of adherence-enhancing interventions for lipid lowering medication in adults for both primary and secondary prevention of cardiovascular disease in an ambulatory setting looking at adherence, serum lipid levels, adverse effects and health outcomes. Studies were selected independently by two review authors.

Data Collection And Analysis: Data were extracted and assessed by two review authors following criteria outlined by the Cochrane Handbook for Systematic Reviews of Interventions.

Main Results: Three additional studies were found in the update and, in total, 11 studies were included in this review. The studies included interventions that caused a change in adherence ranging from -3% to 25% (decrease in adherence by 3% to increase in adherence by 25%). Patient re-enforcement and reminding was the most promising category of interventions, investigated in six trials of which four showed improved adherent behaviour of statistical significance (absolute increase: 24%, 9%, 8% and 6%). Other interventions associated with increased adherence were simplification of the drug regimen (absolute increase 11%) and patient information and education (absolute increase 13%). The methodological and analytical quality of some studies was low and results have to be considered with caution.

Authors' Conclusions: At this stage, reminding patients seems the most promising intervention to increase adherence to lipid lowering drugs. The lack of a gold standard method of measuring adherence is one major barrier in adherence research. More reliable data might be achieved by newer methods of measurement, more consistency in adherence assessment and longer duration of follow up. More recent studies have started using more reliable methods for data collection but follow-up periods remain too short. Increased patient-centredness with emphasis on the patient's perspective and shared decision-making might lead to more conclusive answers when searching for tools to encourage patients to take lipid lowering medication.