High discontinuation rate of statins among PCSK9i users: a nationwide study from 2015-2023

Abstract Background Proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9i) are recommended as additional lipid-lowering drug treatment for high-risk patients if the low-density lipoprotein cholesterol (LDL-C) targets are not achieved with statins and ezetimibe alone. Nationwide data from clinical practice on the use of PCSK9i are lacking. In 2015, PCSK9i became available in Norway with reimbursement restricted to patients with familial hypercholesterolemia (FH) and/or atherosclerotic cardiovascular disease (ASCVD) with LDL-C above certain levels. Purpose To investigate the use and adherence of lipid lowering drugs among a nationwide cohort of PCSK9i users, utlizing complete pharmacy dispensation data. Methods Information on all PCSK9i users ≤80 years with at least one year of follow-up after the first dispensation were extracted from the Norwegian Prescribed Drug Registry. We evaluated adherence to PCSK9i by calculating the proportion of days covered (PDC) during the initial year of PCSK9i therapy. Poor adherence was defined as PDC <80%, and discontinuation was defined as a gap in treatment ≥180 days during the follow-up period. We analyzed treatment patterns of statins and ezetimibe during the 1-year period before and after PCSK9i initiation by determining the proportion of patients with at least one dispensation of statin and/or ezetimibe treatment. Results A total of 2,997 PCSK9i users were identified. Median age at treatment initiation was 62 (IQR: 13) years and 43% were female. Non-adherence to PCSK9i was observed in 16% of the patients, and 18% discontinued treatment (Table). Non-adherence to PCSK9i was more prevalent in females, and in the lowest and highest age quartiles. No significant difference in non-adherence was found among patients with ASCVD compared to patients with FH. In the year preceding PCSK9i initiation, 74% of patients used statins (including combinations with ezetimibe), 11% used ezetimibe monotherapy, and 15% did not use any statin or ezetimibe treatment (Figure). During the year following PCSK9i initiation, 35% used statins (including combinations), 17% used ezetimibe monotherapy, and 48% did not use any statin or ezetimibe treatment. Among patients with ASCVD, 72% used statins prior to PCSK9i initiation, and 22% used statins after. Among patients with FH, 77% used statins prior to PCSK9i initiation, while 51% used statins after. Conclusion In this nationwide study of incident PCSK9i users, we observed a substantial decrease in usage of statins and ezetimibe following PCSK9i initiation. Further, almost 1 in 5 patients discontinued treatment with PCSK9i. There is a large potential for optimizing treatment and adherence to PCSK9i and conventional lipid-lowering drugs among Norwegian patients with ASCVD and familial hypercholesterolemia.Adherence and discontinuation to PCSK9iUse of statin and ezetimibe