Follow-up lipid tests and physician visits are associated with improved adherence to statin therapy

Abstract

The National Cholesterol Education Program recommends regular physician follow-up and lipid testing to promote adherence with lipid-lowering medications. The objective of this study was to determine whether lipid tests and physician visits after treatment initiation are indeed associated with adherence to statin therapy. A retrospective cohort study was conducted among 19 422 enrolees in a US managed care plan who initiated treatment with a statin between October 1999 and August 2001. Computerised pharmacy, medical and laboratory records were used to study the patterns and predictors of adherence with lipid-lowering therapy for up to 3 years. Adherence was assessed in 3-month intervals with patients considered 'adherent' if > or = 80% of days were covered by lipid-lowering therapy. In the first 3 months, 40% of patients had follow-up lipid tests and only 21% had dyslipidaemia visits (14% had both). Those receiving such care were substantially more likely to be adherent in subsequent intervals. Compared with those without follow-up, the relative odds of adherence were 1.42 and 1.27 for patients with one or more lipid test and one or more dyslipidaemia visit, respectively (95% confidence intervals [CI] 1.33, 1.50 and 1.16, 1.39). Patients who received a follow-up visit and lipid test were 45% more likely to be adherent (95% CI 1.34, 1.55). Similar associations were observed when lipid tests and dyslipidaemia visits occurred later in therapy. Early and frequent follow-up by physicians--especially lipid testing--was associated with improved adherence to lipid-lowering therapy. A randomised prospective study is needed to determine whether this relationship is causal.