SAN FRANCISCO, California—African Americans, although only 13% of the US population, now account for more new cases of end-stage renal disease (ESRD) caused by lupus nephritis than do white patients, and comprise 49% of all new cases of lupus kidney failure. Karen H. Costenbader, MD, of Brigham and Women's Hospital in Boston, told the American College of Rheumatology meeting today that this disparity could reflect inadequate health care for lupus and lupus nephritis in this group or could mean that current treatments are less effective for these patients than for other racial and ethnic groups.¹

“In examining the incidence of end-stage renal disease caused by lupus in the US according to age, sex, and racial/ethnic groups, we have found that the incidence is much higher in all minority racial and ethnic groups than in whites, and this gap continues to widen. Incidence rates over the years examined were almost 10 times higher among African-American women than among Caucasian women, ages 20 to 39 years,” Dr. Costenbader said.

49% of US lupus ESRD cases now in black patients

Dr. Costenbader and colleagues studied the nationwide incidence of ESRD due to lupus nephritis from 1995 to 2004 and analyzed incidence rates in different sociodemographic groups. The investigators used data from the US Renal Datasystem, which includes about 94% of all US patients with ESRD. They used age group-, sex-, race-, and ethnicity-stratified data from the 2000 US Census and annual population estimates from 1995 to 2004 to calculate standardized incidence rates. From this, they determined changes in the incidence of ESRD due to lupus nephritis in the entire US population and stratified them according to age, sex, race and ethnicity.

The database included 10,035 incident cases of ESRD due to lupus nephritis. Between 1994 and 2005 the incidence in the entire US population rose from 3.0 to 3.9 cases per million person-years.

The highest incidence was in the 20 to 39 year-old-age group (6.5/million person-years in 2004). Eighty-two percent of cases were in women.

“The standardized incidence rate in women increased 32%, from 4.7 to 6.2/million person years during this time,” Dr. Costenbader said.

Lupus ESRD incidence increased by 37% among blacks (10.5 to 14.4/million person years) and was higher than that for any other racial or ethnic group. Over this period, black lupus patients accounted for 49% of ESRD cases (up from 45% in the previous decade), and the proportion of cases that occurred in white patients fell from 47% to 42%.

ESRD rates in all other groups higher than in whites

According to the investigators, the 2004 standard incidence rates for ESRD due to lupus nephritis were:

• 14.4/million person-years among African Americans
• 4.6/million person-years among Hispanics
• 3.8/million person-years among Asians and Pacific Islanders
• 2.0/million person-years for Caucasians

“The incidence of ESRD due to lupus nephritis rose in the US population from 1995 and 2004. This increase was disproportionately observed among women and blacks. For the first time, the absolute incidence rate in blacks surpassed that in whites. These increases occurred despite clinical trials demonstrating the superiority of cytotoxic-containing immunosuppressive regimens over corticosteroids alone. This suggests decreased access to care and/or decreased efficacy of these therapies for lupus nephritis in black Americans,” Dr. Costenbader concluded.

Reference

1. Costenbader KH, Solomon DH, Winkelmayer W, et al. Incidence of end-stage renal disease due to lupus nephritis in the U.S., 1995-2004. Presented at: ACR 2008 annual meeting; San Francisco, October 28, 2008; Presentation 1927.