Race, Ethnicity, and SLE Drugs

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Lupus nephritis treatment response varies by demographic subpopulation.
Lupus nephritis treatment response varies by demographic subpopulation.

Medications for proliferative nephritis least effective in Hispanics, researchers find.

BOSTON—Among the various racial and ethnic groups in the United States, Hispanics have the worst response to treatment for proliferative nephritis due to systemic lupus erythematosus (SLE), data show.

The findings come from a study of 70 SLE patients with proliferative nephritis, of whom 37 received cyclophosphamide (CYC) and 33 received mycophenolate mofetil (MMF). The group consisted of 10 Caucasians (13%), 14 African Americans (22%), 22 Hispanics (31%), 21 Asians (30%), and three whose race or ethnicity was not known (7%).

Fifteen (40.5%) of the 37 patients treated with CYC had a clinical response, compared with 23 (69.7%) of 33 patients treated with MMF, according to researchers at New York University Medical Center. The two groups were similar with respect to age, gender, race, duration of nephritis, activity and chronicity index, or prior therapy. Patients with Class IV disease, higher serum creatinine, and lower serum albumin, were preferentially treated with CYC. Patients with private insurance were treated preferentially with MMF.

Hispanics had worse outcomes than Caucasians after adjusting for all the variables. The MMF response rate was 100% for Asians, 60% for African Americans, and 45% for Hispanics. The CYC response rate was 60% for Asians, 44% for African Americans, and 9% for Hispanics. For the small numbers of Caucasians in the study, response rates did not differ between MMF and CYC and were superior to the rates for the minority patients.

The investigators defined clinical response as either complete (return to within 10% of normal values for serum creatinine, proteinuria, and urine sediment) or partial remission (improvement of 50% in all renal measurements).

H. Michael Belmont, MD, associate professor of medicine at New York University School of Medicine, who presented findings at the American College of Rheumatology annual meeting, observed: “African Americans and Hispanics appear to have more aggressive and treatment-resistant disease, so they need closer follow-up and more aggressive therapy. They may need to have therapies converted or alternative options considered. We need to look at genetic makeup. Genes in some individual ethnic groups may confer a resistance to certain medications.”

Previous studies also have demonstrated worse outcomes for minorities and patients of low socioeconomic status, suggesting that, in part, access to care and insurance coverage may play a role, Dr. Belmont said. This variable was relatively consistent across the groups studied, as they all received care at a metropolitan hospital where the ability to pay was irrelevant, suggesting that outcomes have more to do with factors intrinsic to the biology of the disease.

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