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 medication regimen is a major factor in the lack of success in treating hyperlipidaemia. In this 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 effect of interventions aiming 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), MEDLINE, EMBASE, PsycInfo and CINAHL. Date of most recent search was in February 2003. No language restrictions were applied.
Selection criteria: Randomised controlled trials of adherence-enhancing interventions to lipid lowering medication in adults for both primary and secondary prevention of cardiovascular disease in an ambulatory setting.
Data collection and analysis: Two reviewers extracted data independently and assessed studies according to criteria outlined by the Cochrane Reviewers' Handbook.
Main results: The eight studies found contained data on 5943 patients. Interventions could be stratified into four categories : 1. simplification of drug regimen, 2. patient information/education, 3. intensified patient care such as reminding and 4. complex behavioural interventions such as group sessions. Change in adherence ranged from -3% to 25% (decrease in adherence by 3% to increase in adherence by 25%). Three studies reported significantly improved adherence through simplification of drug regimen (category 1), improved patient information/education (category 2) and reminding (category 3). The fact that the successful interventions were evenly spread across the categories, does not suggest any advantage of one particular type of intervention. The methodological and analytical quality was generally low and results have to be considered with caution. Combining data was not appropriate due to the substantial heterogeneity between included randomised controlled trials (RCTs).
Reviewers' conclusions: At this stage, no specific intervention aimed at improving adherence to lipid lowering drugs can be recommended. 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. 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.