Abstract 16164: Lipoprotein (a) Testing in Patients With Atherosclerotic Cardiovascular Disease in Five Large U.S. Health Systems

Abstract

Introduction: Lipoprotein (a) [Lp(a)] is an independent, causal risk factor for atherosclerotic cardiovascular disease (ASCVD). Screening patterns remain variable and it is unclear what factors are associated with Lp(a) testing, and whether knowing the Lp(a) value changes management. Research Question: To better understand the proportion of Lp(a) testing, factors predicting Lp(a) testing, and impact on management in ASCVD patients. Methods: A retrospective study using electronic medical record data from five health systems in the CardioHealth Alliance and PCORnet® identified a cohort with an ASCVD diagnosis in 5 years prior to the index date. The index date was defined as the date of the first Lp(a) test result in 2019-2021 for those with a Lp(a) test, or the date of a randomly selected outpatient encounter in 2019-2021 for those without a Lp(a) test. Initiation of lipid lowering therapy (LLT) was assessed within 6 months after the index date. Multivariable regression modeling was used to determine factors associated with Lp(a) testing. Results: Among 595,685 ASCVD participants, only 2,588 (0.4%) were tested for Lp(a). In adjusted models, those who were older, Black, or Hispanic were less likely to have Lp(a) testing, while those with familial hypercholesterolemia, ischemic stroke/TIA, PAD, prior LLT, or LDL-C ≥130mg/dL were more likely to be tested (table). Those with elevated Lp(a) (>50mg/dL or >125 nmol/L) were more likely to initiate any LLT (43.9% vs 34.6%, p=0.03), particularly PCSK9i (10.9% vs 4.8%, p<0.01) and ezetimibe (11.5% vs 5.9%, p <0.01) compared to those without elevated Lp(a). Statin initiation remained similar between those with and without elevated Lp(a) (32.1% vs 29.5%, p=0.47). Conclusion: Lp(a) testing in ASCVD patients is infrequent, with evidence of disparities by race and ethnicity. Having elevated Lp(a) was associated with higher initiation of non-statin LLT. However, overall initiation of any LLT after an elevated Lp(a) test was low.