Lipoprotein(a) Testing Patterns in a Large Health System

Lipoprotein (a) [Lp(a)] is associated with increased risk of atherosclerotic cardiovascular disease (ASCVD). As directed therapy for Lp(a) emerges, it is important to understand patterns of Lp(a) testing in routine clinical practice. We set out to characterize Lp(a) testing across a large academic health system. Using electronic health record (EHR) data from 2014 to 2019, we compared patients who underwent Lp(a) testing to date-matched peers who had low density lipoprotein (LDL-C) assessment alone. We analyzed ordering provider characteristics and rates of initiation of new lipid lowering therapy (LLT) within 12 months after testing. Of 1,296 adults with Lp(a) test results, 629 (48.5%) had prior history of ASCVD and 667 (51.4%) did not. Compared with those with LDL-C testing alone, individuals who underwent Lp(a) testing were more like to have a myocardial infarction or ischemic stroke at a young age and multiple prior cardiovascular events. Though the majority of Lp(a) tests were ordered in outpatient encounters, a higher proportion of Lp(a) tests compared with LDL-C tests were performed in the inpatient setting. Neurology and psychiatry were the most common specialty to order Lp(a) tests in our cohort. There was a significantly increased initiation of LLT after Lp(a) testing compared with LDL-C testing across all medication types. Consistent with guidelines, Lp(a) testing is used in those with early onset ASCVD, and among those with multiple cardiovascular events. Lp(a) testing is associated with more aggressive LLT in following year. Further research is needed to characterize Lp(a) testing across larger populations.