PREDICTORS OF LIPOPROTEIN(A) TESTING ACROSS A NATIONAL COHORT: INSIGHTS FROM THE VETERANS HEALTH ADMINISTRATION

Abstract

Therapeutic Area: ASCVD/CVD Risk Factors Background: Lipoprotein(a) [Lp(a)] is a genetically determined, independent, causal risk factor for atherosclerotic cardiovascular diseases (ASCVD). Multiple practice guidelines increasingly recommend Lp(a) testing to refine cardiovascular risk assessment. We aimed to evaluate sociodemographic and clinical factors influencing Lp(a) testing in the Veterans Affairs (VA) healthcare system. Methods: We assembled a retrospective cohort using data from the VA electronic health record, Medicare claims, and community care for Veterans having at least one outpatient visit in the VA between July 1, 2020, and June 30, 2023, and at least one prescription filled in 180 days before the date of the last VA outpatient encounter to ensure adequate healthcare system contact. We evaluated patient-level sociodemographic and clinical predictors of Lp(a) testing. Predictors included self-reported race and ethnicity, social vulnerability, the presence and type of ASCVD, and low-density lipoprotein cholesterol (LDL-C) levels. Neighborhood social vulnerability was defined using the CDC's Social Vulnerability Index (SVI) and categorized by quartiles (higher numbers associated with higher vulnerability). Associations between patient characteristics and Lp(a) testing were estimated using generalized estimating equations. Results: Among 5,331,271 Veterans, the median age was 67 years (IQR 52-76) with 10.3% female; 69.6% identified as White, 18.8% Black, 7.4% Hispanic. Less than 1% of eligible Veterans have received Lp(a) testing. Lp(a) was more likely to be tested among Veterans with older age, White race, non-Hispanic ethnicity, living in urban neighborhoods, and those with low SVI (less vulnerable neighborhoods). After multivariable adjustment, Lp(a) testing was more likely among women, Veterans identified as Black or Asian, and those with established ASCVD (Figure). Across 130 VA facilities, Lp(a) testing ranged from 0.01-3.40%. The median Lp(a) level among those tested at VA facilities was 16 mg/dL (IQR 6-53) with 26% of Veterans with ASCVD and 20% of Veterans without ASCVD having Lp(a) levels >50 mg. Conclusions: Lp(a) testing is infrequent in the VA healthcare system, with disparities in testing by sociodemographic and clinical characteristics. About a quarter of those tested had elevated Lp(a) levels. Developing strategies to improve overall Lp(a) testing and reduce existing gaps in testing by sociodemographic factors is critical as targeted therapeutics become available.