Rates of both ischemic and hemorrhagic strokes in systemic lupus erythematosus (SLE) are affected by the racial and ethnic background of patients, a U.S. study reports, which may help to better identify people most at risk and aid in prevention.
Specifically, the study found that black SLE patients in the U.S. were at a 34% higher risk of a stroke than white patients, while Hispanics had a 25% greater risk.
Strokes are more common in SLE patients generally than in people without this disease. And previous studies of the U.S. population have shown racial variations in cardiovascular disease (CVD), including stroke, among SLE patients, with blacks having higher mortality and CVD rates than whites, and those of Hispanic and Asian backgrounds having lower mortality and CVD rates than whites.
For this reason, “Racial/ethnic variation in stroke rates and risks among patients with systemic lupus erythematosus,” which was published in the journal Seminars in Arthritis and Rheumatism, examined racial variations in rates and risks of stroke in general, and its two subtypes, among SLE and lupus nephritis (LN) patients.
Researchers in Boston and New York used data from Medicaid, a U.S. health insurance provider for those with low incomes and limited resources, regarding adults ages 18 to 65 in the 29 most-populous states between 2000 and 2010. SLE and LN patients were identified using a standard international classification of disease criteria, while race/ethnicity was self-reported.
In total, 65,788 SLE patients were identified. Their median age was 40.8, and their racial backgrounds were: 42% black, 38% white, 16% Hispanic, 3% Asian, and 1% Indian/Alaska Natives. Within these SLE cases, 23% were identified as having LN (14,787 people, mean age of 37.8).
During a mean follow-up of 3.7 years, 1,441 first stroke events (1,208 ischemic and 233 hemorrhagic strokes) were recorded. In conducting its analysis, the research team took into account stroke risk factors (hypertension, heart failure, and CVD), the presence of LN, medication use, and sociodemographic factors.
Among black patients, the risk of both hemorrhagic and ischemic stroke was seen to be higher than whites — 42% and 33%, respectively. Blacks were also found to have the highest rates of hypertension, heart failure, LN, and CVD of all racial and ethnic groups.
Hispanics had a 79% higher risk for hemorrhagic strokes than white SLE patients, but both white and Hispanic SLE patients had similar risks for ischemic stroke.
The mean age for a first stroke in SLE patients overall was 47, with American Indians/Alaskan natives having a first stroke at the oldest mean age (51) and Asians at the youngest (43.79). But both younger blacks and Hispanics, those in age groups 18-39 and 40-49, had higher overall stroke risks than did white SLE patients in those age groups.
“Stroke risks (overall and by subtype) were particularly increased among Black and Hispanic SLE patients < age 50, which may be partially explained by the accelerated and premature atherosclerosis observed in younger patients with SLE,” the researchers noted.
Among lupus nephritis patients, 365 stroke events requiring hospitalization were recorded (285 ischemic, 80 hemorrhagic) during the roughly three years studied, and the age at first stroke was younger (mean of 43.56 years) than in the overall SLE group. Black and Hispanic LN patients in the 40-49 age group continued to be at a higher stroke risk overall than white LN patients, the researchers found.
Reasons for the racial and ethnic differences seen could involve the effects of hypertension, untreated risk factors such as diabetes and weight, as well as racial differences in SLE severity, the study suggested.
It concluded by noting that “future research confirming the current findings and investigating factors such as genetics, biomarkers, lifestyle factors such as diet and physical activity, medications, other thrombotic risk factors is needed.”