Association between statin discontinuation after proprotein convertase subtilisin/kexin type 9 inhibitor initiation and subsequent atherosclerotic cardiovascular disease events.

Background: Clinical guidelines recommend the use of proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9is) in patients with atherosclerotic cardiovascular disease (ASCVD) and nonoptimal low-density lipoprotein.

Objective: To evaluate the association between discontinuation of statin use after PCSK9i initiation and subsequent ASCVD events.

Methods: This pre-post retrospective comparative study used national administrative data of adult statin medication users (age ≥18 years) with an index PCSK9i claim (January 1, 2019, to April 30, 2021), prior ASCVD diagnosis, and a 2-year follow-up period. Proportions and probability of ASCVD events post-index (PCSK9i) vs pre-index (PCSK9i) for patients who discontinued statins (discontinued cohort) and those who continued statins (continued cohort) were compared. Propensity score weighting was used to balance patient baseline characteristics. Multivariate Poisson regression and time-to-event Cox regression models were used to assess the association between statin discontinuation and ASCVD events.

Results: There were 294 and 46 patients in the continued and discontinued cohorts, respectively. Unweighted results showed that patients in the continued cohort were more likely to receive high-intensity statins (32% vs 22%; P = 0.4) and have a Charlson Comorbidity Index score of 3 or more (62% vs 54%; P  =  0.5) at baseline. Baseline statin adherence was lower in the discontinued cohort (6.7% vs 59%; P < 0.001) but 30% each in the propensity 1:1 matched cohort. The 2 cohorts (after matching) had similar ASCVD event prevalence (discontinued cohort: 24% vs continued cohort: 26%) in the baseline and the same lower prevalence (6.5% each; P > 0.9) in the 24-month follow-up period. The odds of any ASCVD event post-index was comparable between the 2 cohorts (reference: continued cohort; odds ratio = 1.88; 95% CI = 0.28-14.6; P = 0.51). There were no statistically significant differences between the 2 groups in the Cox regression (P = 0.47).

Conclusions: Post-ASCVD event rates were significantly lower in both cohorts, but discontinuation of statins was not associated with unfavorable ASCVD outcomes.