Context: Landmark clinical trials have demonstrated the survival benefits of statins, with benefits usually starting after 1 to 2 years of treatment. Research prior to these trials of older lipid-lowering agents demonstrated low levels of 1-year adherence.
Objective: To compare 2-year adherence following statin initiation in 3 cohorts of patients: those with recent acute coronary syndrome (ACS), those with chronic coronary artery disease (CAD), and those without coronary disease (primary prevention).
Design and setting: Cohort study using linked population-based administrative data from Ontario.
Patients: All patients aged 66 years or older who received at least 1 statin prescription between January 1994 and December 1998 and who did not have a statin prescription in the prior year were followed up for 2 years from their first statin prescription. There were 22,379 patients in the ACS, 36,106 in the chronic CAD, and 85,020 in the primary prevention cohorts.
Main outcome measures: Adherence to statins, defined as a statin being dispensed at least every 120 days after the index prescription for 2 years.
Results: Two-year adherence rates in the cohorts were only 40.1% for ACS, 36.1% for chronic CAD, and 25.4% for primary prevention. Relative to the ACS cohort, nonadherence was more likely among patients receiving statins in the chronic CAD (relative risk [RR], 1.14; 95% CI, 1.11-1.16) and primary prevention cohorts (RR, 1.92; 95% CI, 1.87-1.96).
Conclusions: Elderly patients with and without recent ACS have low rates of adherence to statins. This suggests that many patients initiating statin therapy may receive no or limited benefit from statins because of premature discontinuation.