Healthcare system level testing for lipoprotein(a) amongst ischemic and cryptogenic stroke patient population

Abstract

Background/Synopsis

Elevated Lp(a) is associated with the incidence of premature coronary heart disease, aortic stenosis, and ischemic stroke. While its association with strokes secondary to large artery atherosclerosis is robust, data on Lp(a) and its involvement in cryptogenic stroke or embolic stroke of undetermined source (ESUS) is scarce. Even though the National Lipid Association (NLA) recommends Lp(a) testing for all individuals, clinically Lp(a) testing remains limited in stroke patients.

Objective/Purpose

This study aims to assess both the frequency at which Lp(a) is checked in patients presenting with ischemic stroke, including cryptogenic stroke, within the University of Pittsburgh Medical Center (UPMC) health system and the association of Lp(a) with cryptogenic stroke.

Methods

We queried the UPMC electronic healthcare records (EHR), spanning over 40 hospital and 200 outpatient sites, from 2010 to 2020 to identify individuals with ICD-9 and ICD-10 codes consistent with non-hemorrhagic ischemic strokes and cryptogenic strokes. Demographic, medications, comorbidity, and serologic/biomarker data was additionally obtained within one year of stroke for patients ages 18 – 60 and with ICD-9 or ICD-10 codes for cryptogenic stroke, stroke, ischemic stroke, or cerebral vascular incident. Exclusion criteria includes age < 18 or > 60 or history of hemorrhagic stroke.

Results

A total of 14,689 patients met inclusion criteria for this study. 8,395 (57.1%) were male and 6,294 (42.8%) were female. 6,386 individuals (43.4%) had an ischemic stroke based on ICD-9 and ICD-10 diagnosis codes and 8,303 (56.5%) individuals had a cryptogenic stroke based on ICD-9 and ICD-10 diagnosis codes. Of note, 1,262 (8.6%) individuals had a transient ischemic attack based on ICD-9 and ICD-10 diagnosis codes; this diagnosis was included under cryptogenic stroke only. Only 132 (0.9%) individuals had Lp(a) tested: 59 (0.9%) in those with ischemic stroke and 73 (0.9%) in those with cryptogenic stroke (p-value 0.78). The mean Lp(a) value in those with ischemic stroke was 73.0 nmol/L (range 21.0 – 2370.0 nmol/L) and the mean Lp(a) value in those with cryptogenic stroke was 44.0 nmol/L (range 17.0 – 174.0 nmol/L) (p-value 0.262).

Conclusions

Our study demonstrates that despite the NLA's societal recommendation for universal Lp(a) testing, Lp(a) remains undertested in a high risk stroke population within a large health system spanning rural and urban areas. Given the small numbers in this population, an ongoing, prospective arm to this study has been designed to evaluate Lp(a) in patients presenting with cryptogenic stroke.