Abstract 11355: Contemporary Patterns of Lipoprotein(a) Testing and Associated Clinical Care and Outcomes

Abstract

Introduction: Elevated lipoprotein(a) [Lp(a)] is associated with atherosclerotic cardiovascular disease (ASCVD), yet little is known about Lp(a) testing patterns in real-world practice. We hypothesized that Lp(a) testing occurs in a different population than calculated low density lipoprotein (LDL-C) testing alone, and that elevated Lp(a) is associated with greater lipid-lowering therapy (LLT) initiation and cardiovascular (CV) events. Methods: We used data from 11 health systems participating in the National Patient-Centered Clinical Research Network. We created two cohorts based on lab tests from Jan 1, 2015 to Dec 31, 2019: 1) the Lp(a) cohort, of adults with an Lp(a) test and 2) the LDL-C cohort, of 4:1 date- and site-matched adults with an LDL-C test, but no Lp(a) test. We used logistic regression to assess the relationship between Lp(a) levels (< 50, 50-100, and > 100mg/dL) and initiation of LLT within 3 months; and cox proportional hazards to evaluate Lp(a) levels and time to all-cause hospitalization and the composite of MI, revascularization and ischemic stroke hospitalization. Results: Overall, 20,551 patients (0.06% per year) had Lp(a) tests, with median Lp(a) value 17.5mg/dL (Q1, Q3: 7.0, 56.0). Compared with the LDL-C cohort (N=82,204), the Lp(a) cohort more frequently had ASCVD (24.3% vs. 8.5%) or multiple prior CV events (8.6% vs. 2.6%). Elevated Lp(a) was associated with greater odds of LLT initiation (Figure 1). Elevated Lp(a) was not significantly associated with all-cause hospitalization; however, Lp(a) > 100mg/dL was correlated with composite CV hospitalization compared with Lp(a) < 50mg/dL [adj HR (95% CI): 1.24 (1.06-1.44), p=0.006]. Conclusions: Lp(a) testing occurs more often in adults with ASCVD and multiple CV events, but testing is infrequent. Elevated Lp(a) was associated with LLT initiation, including niacin, despite lack of evidence of CV benefit. There was an association between elevated Lp(a) and CV hospitalization outcomes.