Persistence and Adherence to PCSK9 Inhibitor Monoclonal Antibodies Versus Ezetimibe in Real-World Settings

The cardiovascular disease risk reduction benefits of proprotein convertase subtilisin/kexin type 9 inhibitor monoclonal antibodies (PCSK9i mAb) and ezetimibe are dependent on remaining on treatment and being persistent and adherent. We estimated the percentage of patients on therapy, persistent and adherent at 182 and 365 days among US adults with health insurance who initiated a PCSK9i mAb (n = 16,588) or ezetimibe (n = 83,086) between July 2015 and December 2019. Using pharmacy fill claims, being on therapy was defined as having a day of medication supply in the last 60 of 182 and 365 days following treatment initiation, being persistent was defined as not having a gap of 60 days or more between the last day of supply from one prescription fill and the next fill, and being adherent was defined by having medication available to take on ≥ 80% of the 182 and 365 days following treatment initiation. We estimated multivariable-adjusted risk ratios for being persistent and adherent comparing patients initiating PCSK9i mAb versus ezetimibe using Poisson regression. At 182 days following initiation, 80% and 68% were on therapy and 76% and 64% were persistent among patients who initiated a PCSK9i mAb and ezetimibe, respectively. Among patients who were on therapy and persistent at 182 days following initiation, 88% and 81% of those who initiated a PCSK9i mAb and ezetimibe, respectively, were on therapy at 365 days. Among those on therapy and persistent at 182 days following initiation, being persistent and being adherent at 365 days were each more common among PCSK9i mAb versus ezetimibe initiators (persistent: 82% versus 76%, multivariable-adjusted risk ratio 1.07; 95% confidence interval CI 1.06–1.08; adherent: 74% versus 71%, multivariable-adjusted risk ratio 1.02; 95% CI 1.01–1.03). These data suggest approaches to increase persistence and adherence to PCSK9i mAb and ezetimibe should be implemented prior to or within 182 days following treatment initiation.