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). However, testing patterns remain variable and it is unclear what patient level factors are associated with Lp(a) testing, and if testing changes clinical management. Methods A retrospective study using electronic medical record data from five health systems in the CardioHealth Alliance identified an ASCVD cohort that was divided into those with a Lp(a) test and those without a Lp(a) test between 2019-2021. Baseline characteristics and initiation of lipid lowering therapy (LLT) was assessed. Multivariable regression modeling was used to determine factors associated with Lp(a) testing. Results Among 595,684 ASCVD patients, only 2,587 (0.4%) were tested for Lp(a) between 2019 and 2021. In adjusted models, those who were older or Black 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. Those with a Lp(a) test, regardless of the Lp(a) value, were more frequently initiated on any statin therapy (30.3% vs. 10.6%, p<0.001), ezetimibe (7.65 vs. 0.8%, p <0.001), or PCSK9i (6.7% vs. 0.3%, p <0.001) compared with those without a test. Those with an elevated Lp(a) level more frequently initiated ezetimibe (11.5% vs. 5.9%, P <0.001) or PCSK9i (10.9% vs. 4.8%, P <0.001), but not statin therapy. Conclusions Lp(a) testing in ASCVD patients is infrequent, with evidence of disparities among older or Black individuals. Testing for Lp(a), regardless of level, is associated with greater initiation of any LLT, while elevated Lp(a) is associated with greater initiation of non-statin LLT. Overall, initiation of LLT remained low, despite guideline indications for LLT in ASCVD patients. There is a critical need for multidisciplinary and inclusive approaches to raise awareness for Lp(a) testing and its implications on management.