Factors Associated with Lipoprotein(a) Testing Among Multiethnic Individuals

Background

Lipoprotein(a) [Lp(a)] is a causal risk factor for atherosclerotic cardiovascular disease (ASCVD) and clinical guidelines recommend incorporating Lp(a) testing in routine care.

Objective

Examine real-world, contemporary clinical testing patterns of Lp(a) among multiethnic populations.

Design

In this nested case–control study, we assessed the prevalence and factors associated with Lp(a) testing within a large Northern Californian health system between 2010 and 2021. Incident density matching was used to select controls matched with a case for a case:control ratio of up to 1:5. Conditional logistic regression was used to assess the relationship between Lp(a) testing, sociodemographic, and clinical characteristics.

Participants

We included individuals aged 18 years or older with ≥ 2 primary care visits during the study period.

Main Measures

Lp(a) testing rates over time and factors associated with testing based on demographic, medical, and healthcare utilization variables.

Key Results

Of the 1,484,410 individuals in the cohort, 14,818 (1.0%) underwent Lp(a) testing. The median Lp(a) level was 35 mg/dL and over a third of individuals had Lp(a) levels > 50 mg/dL. After adjustment, South Asian individuals were three times more likely to have undergone Lp(a) testing, as compared to non-Hispanic White individuals [OR = 3.19, (95% CI = 2.98, 3.41)], while those identified as non-Hispanic Black and Hispanic were significantly less likely to have undergone Lp(a) testing [OR = 0.70, (95% CI = 0.62, 0.80) and 0.64 (95% CI = 0.59, 0.69), respectively]. Those with a history of ASCVD had over twice the odds of undergoing testing [OR = 2.14 (95% CI = 1.99, 2.29)], as did individuals with more frequent primary care visits [OR = 1.99 (95% CI = 1.84, 2.15)].

Conclusions

Lp(a) testing rates in real-world settings are low, with significant disparities by race, ethnicity, and healthcare utilization. Expanding access to Lp(a) testing may help reduce disparities within ASCVD risk assessment and treatment as new targeted therapeutic agents become available.