Dynamics of long-term adherence to lipid-lowering therapy in patients after myocardial infarction.

Despite recommendations to use oral lipid-lowering therapies (LLT) in secondary prevention of atherosclerotic cardiovascular disease, numerous studies have shown substantial under-utilization. We assessed long-term persistence and dynamics of adherence to oral LLTs in patients after their first ever myocardial infarction (MI) in Sweden. A total of 83,407 patients with a MI (2010–2017) and who were dispensed an oral LLT were identified through Swedish nationwide health registries. After one, three and eight years of follow-up, persistence to lipid-lowering therapies was 90.3%, 71.1% and 50.8%, respectively. Adherence, quantified using the proportion of days covered (PDC), was a highly dynamic phenomenon with patients frequently moving between categories (high, medium, and low) of adherence. Adherence was high among persistent patients (> 70% had PDC ≥ 80%), but only 30% regained high adherence following non-persistence. Higher age, prescription from primary care, and higher income were associated with lower risk of non-persistence whereas higher comorbidity index, no prior statin use and concomitant use of platelet inhibitors were associated with increased risk. This study highlights the dynamic nature of adherence at the patient-level and that particular focus on adherence may be needed following non-persistence. Socioeconomic and clinical factors associated with non-persistence were identified, which in turn may help target measures to improve adherence in this high-risk patient group.