— Notable risks for young patients and those with lupus nephritis
Minority patients in the U.S. with systemic lupus erythematosus (SLE) were at increased risk of strokes compared with whites, an analysis of Medicaid data showed.
After multivariate adjustment, black patients with lupus had a 34% increased risk for any stroke (HR 1.34, 95% CI 1.18-1.53), while Hispanics had a 25% increased risk (HR 1.25, 95% CI 1.06-1.47), according to Medha Barbhaiya, MD, of the Hospital for Special Surgery in New York City, and colleagues.
Blacks also were at elevated risk for both hemorrhagic strokes (HR 1.42, 95% CI 1-2.01) and ischemic strokes (HR 1.33, 95% CI 1.15-1.52) compared with whites, while Hispanics were at increased risk for hemorrhagic stroke only (HR 1.79, 95% CI 1.22-2.61), the researchers reported in Seminars in Arthritis & Rheumatism
Stroke accounts for almost one-third of lupus deaths, and minority SLE patients tend to have more severe disease and end-organ damage than whites.
Stroke risk is thought to be particularly high among patients with lupus nephritis, who often have hypertension and dyslipidemia, and use high-dose steroids, and also among younger patients regardless of their traditional risk factors.
"Whereas risk of stroke shows substantial sociodemographic variation in the general U.S. population, little is known about racial/ethnic variation in risk of ischemic and hemorrhagic stroke and specific risk factors among SLE patients," the researchers wrote.
To examine these factors, Barbhaiya and colleagues analyzed Medicaid billing claims from the most populous 29 states from 2000 to 2010 for patients ages 18 to 65.
Overall risk was assessed on the SLE risk adjustment index, which includes comorbidities such as chronic renal failure, pericarditis, and hemolytic anemia.
Of the 65,788 cases of SLE included in the analysis, 93% were women, and 40% lived in the South. Mean age was 40.8, and 47% of patients were ages 18 to 39.
A total of 42% were black, 38% were white, 16% were Hispanic, 3% were Asian, and 1% were American Indian/Alaska Native.
The prevalence of comorbidities differed among the ethnic groups. Whites most often had atrial fibrillation and anticoagulation, blacks had the highest rates of heart failure and hypertension, American Indian/Alaska Natives had the highest rates of diabetes and obesity, and Asians most often had lupus nephritis and end-stage renal disease.
During a mean follow-up of 3.7 years, there were 1,441 stroke events, 1,208 of which were ischemic and the remainder, hemorrhagic. The incidence rates were 5.88 (95% CI 5.58-6.19) per 1,000 person-years for any stroke, 4.92 (95% CI 4.65-5.21) for ischemic strokes, and 0.94 (95% CI 0.83-1.07) for hemorrhagic strokes. The average age for SLE patients to experience a first stroke was 47.
A total of 23% of the cohort had lupus nephritis. Compared with the entire cohort, the nephritis patients were younger, with a mean age of 37.8. These patients also had higher rates of multiple comorbidities, including angina, coronary atherosclerosis, diabetes, stroke, heart failure, myocardial infarction, and end-stage renal disease. Patients with lupus nephritis also had higher rates of any cardiovascular disease than the larger cohort did (41% versus 25%).
During slightly over 3 years of follow-up, there were 365 stroke-related hospital admissions among patients with lupus nephritis. The rates for any stroke among nephritis patients were 8.01 per 1,000 patient-years, while the rates for ischemic and hemorrhagic strokes were 6.23 and 1.73 per 1,000, respectively.
The risk of stroke also was significantly increased among patients ages 40 to 49 for blacks (HR 2.83, 95% CI 1.53-5.22) and Hispanics (HR 2.47, 95% CI 1.24-4.92). This increased stroke risk among younger minority patients suggests that "early recognition and aggressive risk factor management may be critical" for these patients, the researchers noted.
They explained that they were unable to provide a biologic rationale for the observed discrepancies in stroke rates, but pointed to potential contributors such as the effects of hypertension, obesity, dyslipidemia, and diabetes, as well as differences in SLE severity.
"We also cannot determine the extent to which the differences we observe are due to biologic differences (that we cannot measure) versus disparities in access to care that go beyond obtaining Medicaid coverage," they wrote.
"Further research confirming the current findings and investigating factors such as genetics, biomarkers, lifestyle factors such as diet and physical activity, medications, and other thrombotic risk factors is needed."
A limitation of the study was its reliance on administrative data, which may allow misclassification of cases, the researchers noted.
The study was supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases and the Rheumatology Research Foundation.
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Seminars in Arthritis & Rheumatism
Source Reference: Barbhaiya M, et al "Racial/ethnic variation in stroke rates and risks among patients with systemic lupus erythematosus" Semin Arth Rheum 2018; doi:10.1016/j.semarthrit.2018.07.012.
Read the original article on Medpage Today: Stroke Risk High for Minority Lupus Patients