Patient adherence to fully reimbursed proprotein convertase subtilisin/kexin type 9 inhibitor (PCSK9i) treatment.

AIMS: Proprotein convertase subtilisin/kexin-type 9 inhibitor (PCSK9i) treatment reduces cardiovascular events when taken over a long time for secondary prevention. Data on treatment adherence are scarce and maybe affected by co-payment of patients. The aim of this study was to elucidate PCSK9i treatment adherence in a setting of full cost coverage as it is the case in a number of European countries. METHODS AND RESULTS: Baseline data and prescription patterns of all 7302 patients with PCSK9i prescriptions dispensed on the account of Austrian Social Insurances between September 2015 and December 2020 were retrieved and analyzed. A gap of ≥ 60 days between prescriptions was defined as treatment discontinuation. Patient adherence was evaluated as the proportion of days covered (PDC) over the observation period and treatment discontinuation rates were investigated by the Kaplan-Meier method. The mean PDC was 81.8% and was significantly lower in female patients. A PDC of ≥ 80% indicating adequate adherence was found in 73.8%. Of the study population 27.4% discontinued PCSK9i treatment and 49.2% thereof re-initiated treatment during the observation period. Most of the patients who discontinued treatment did so within the first year. Male patients and patients under 64 years showed significantly lower discontinuation and higher re-initiation rates. CONCLUSION: Considering the high PDC and low discontinuation rates, the majority of patients adhere to PCSK9i treatment. Hence, in a system where PCSK9i treatment is made available at virtually no costs for patients this highly effective treatment is well-accepted as a long-term treatment.