Lipoprotein(a) testing in Patients with Atherosclerotic Cardiovascular Disease in Five Large U.S. Health Systems

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. ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial N/A, this was not a clinical trial ### Funding Statement Novartis Pharmaceuticals Corporation provided funding with a grant to support this study, including the principle investigators, corresponding author, and statistical support effort. The analytic plan, data analysis, data interpretation, or decision to publish as the study was investigator initiated with collaboration with the sponsor. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study was approved by the Duke University institutional review board under a waiver of HIPAA authorization and informed consent I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data will be made available upon request