Race/ethnic and sex differences in the initiation of non-statin lipid-lowering medication following myocardial infarction

Background: Adults with atherosclerotic cardiovascular disease (ASCVD) at very high-risk for recurrent events who have low-density lipoprotein cholesterol ≥ 70 mg/dL despite maximally-tolerated statin therapy are recommended to initiate ezetimibe or a proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor.

Objective: Compare the initiation of ezetimibe and a PCSK9 inhibitor after a myocardial infarction (MI) among very high-risk ASCVD patients by race/ethnicity and sex.

Methods: We analyzed data from 374,786 adults ≥ 66 years of age with Medicare fee-for-service coverage who had an MI between July 1, 2015 and December 31, 2018, were not taking ezetimibe or a PCSK9 inhibitor, and had very high-risk ASCVD defined by the 2018 American Heart Association/American College of Cardiology multi-society cholesterol guideline. Pharmacy claims through December 31, 2018 were used to determine ezetimibe and PCSK9 inhibitor initiation.

Results: Overall, 6980 (1.9%) beneficiaries initiated ezetimibe, and 1433 (0.4%) initiated a PCSK9 inhibitor. Adjusted hazard ratios (aHR) for ezetimibe initiation among non-Hispanic Black, Hispanic, and Asian versus non-Hispanic White beneficiaries were 0.77 (95% confidence interval [95%CI]: 0.70-0.86), 0.92 (95%CI: 0.76-1.11) and 0.73 (95%CI: 0.59-0.89), respectively. Compared to non-Hispanic White beneficiaries, the aHRs for PCSK9 inhibitor initiation were 0.63 (95%CI: 0.48-0.81) among non-Hispanic Black, 0.70 (95%CI: 0.43-1.13) among Hispanic, and 0.93 (95%CI: 0.62-1.39) among Asian beneficiaries. The aHRs for ezetimibe and PCSK9 inhibitor initiation comparing women to men were 1.11 (95%CI: 1.06-1.17) and 1.13 (95%CI: 1.01-1.25), respectively.

Conclusion: There are race/ethnic and sex disparities in the initiation of ezetimibe and a PCSK9 inhibitor following MI among very high-risk ASCVD patients.