Asian and Hispanic patients with systemic lupus erythematosus have lower all-cause mortality rates than white, black, and Native American patients, according to an analysis of Medicaid claims for 42,221 adult lupus patients published online Jan. 15 in Arthritis & Rheumatology.
As with blacks and Native Americans, previous studies have reported more severe disease among Hispanics, so “our finding of decreased mortality rates and adjusted risks among Hispanic adults with SLE was thus surprising,” said investigators from Brigham and Women’s Hospital, Boston, and the University of Alabama at Birmingham.
The findings don’t necessarily contradict earlier research. It could be that even with more severe disease, Hispanic patients live longer. That’s been found before for cardiovascular disease, and has even been dubbed the “Hispanic paradox.” Perhaps “higher neighborhood social cohesion and family and social support … improve health outcomes” in Hispanic and Asian communities, they said.
Dr. Karen Costenbader
The investigators analyzed the patients’ histories over a mean follow-up period of 2.56 years and found that per 1,000 patient-years, there were 5.18 deaths among Asians, 7.12 among Hispanics, 20.17 among whites, 24.13 among blacks, and 27.52 among Native Americans. The analysis included claims filed between 2000 and 2006 from 47 states and the District of Columbia.
Compared with white patients, the risk of all-cause mortality was 52% lower for Hispanic (hazard ratio, 0.48; 95% confidence interval, 0.40-0.59) and 41% lower for Asian patients (HR, 0.59; 95% CI, 0.40-0.86), but 21% higher for black (HR, 1.21; 95% CI, 1.10-1.33) and 40% higher for Native American patients (HR, 1.40; 95% CI, 1.04-1.90). The results were adjusted for comorbidities, demographics, and socioeconomic confounders (Arthritis Rheumatol. 2015 Jan. 15 [doi:10.1002/art.38981]).
Among the 8,191 subjects with lupus nephritis (LN), Hispanic and Asian patients had lower all-cause mortality than did whites. LN mortality was similar between white, black, and Native Americans, maybe due to the smaller LN sample size, the investigators said.
The study suggests future research directions, rather than offering immediate clinical guidance. It’s known that black LN patients generally need higher doses of mycophenolate mofetil and cyclophosphamide than white patients, but how to otherwise handle racial variations in lupus – and other diseases – is not yet clear. A complex dance of genetics and environmental factors is probably at work, said senior investigator Dr. Karen Costenbader, codirector of the lupus center at Brigham and Women’s Hospital.
“Ultimately, the goal is to understand the factors contributing to increased mortality in SLE, in order to modify risk factors and provide tailored therapies to enhance survival.” In the meantime, “clinicians should be aware that among lupus patients, African and Native Americans are doing much more poorly” than others, she said in an interview.
The patients were 18-65 years old, had been enrolled in Medicaid for at least 3 months, and had at least three claims filed for lupus at least 30 days apart. LN patients had at least two additional claims for glomerulonephritis, proteinuria, or renal failure. The study focused on all-cause mortality because the cause of death wasn’t usually reported in the claims data.
Patients’ socioeconomic status was estimated by median household income and other census zip code data.
Dr. Costenbader said she has no relevant disclosures. The work was funded by the National Institute of Arthritis and Musculoskeletal and Skin Diseases, among others.