Racial Disparities Result in Unprecedented Differences in Outcomes for SLE Patients

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The differences between Caucasian and minority patients with lupus are striking: In almost all aspects of the disease, black, Hispanic and many Asian lupus patients do poorly compared with their white counterparts. Although racial disparities in outcomes in the practice of medicine are widespread, the scope and degree of the differences in lupus is, with only a few exceptions, unprecedented. From disease risk and severity, to treatment response, to mortality, there are stark differences in how the disease affects patients of different racial backgrounds. Despite decades of research, improvements in outcomes for minority patients with lupus remain largely elusive.

Magnitude of the Problem

We have known for almost half a century that a dramatic difference exists in the prevalence and severity of lupus in black patients in particular, compared with white patients. Epidemiologic studies from the 1960s showed an almost threefold increase in the prevalence of lupus among black individuals, with an almost threefold difference specifically in women. Later studies showed similar findings among Hispanics and individuals from certain Asian backgrounds.^1,2 Moreover, as far back as the mid-1970s, significant mortality risks were apparent in black females, in whom the mortality rate was almost four times as high in white females.³

Subsequent research demonstrated that lupus tends to occur at a younger age and tends to be more severe in non-white patients. Black patients, for example, are more likely to have renal and neurologic involvement due to lupus, and black, Asian and Hispanic patients are up to twice as likely to develop lupus nephritis within 10 years of diagnosis. Worse still, the incidence of progression to end-stage renal disease from lupus nephritis is actually on the rise for black patients, according to U.S. Renal System data.⁴ Furthermore, black lupus patients are much more likely to have high-risk histological features on renal biopsy, such as crescents and high chronicity indexes, and are much more likely to have WHO class III nephritis, which has been associated with poor outcomes.⁵

Complicating matters are clear differences in response to treatment among non-white patients, especially with lupus nephritis—an all-too-common manifestation. Intravenous cyclophosphamide, the gold standard treatment for lupus since the early 1990s, has been shown to be markedly less effective in black patients. A landmark study by Dooley et al in 1996, for example, demonstrated a dramatic difference among black patients in the response to monthly pulse-dose IV cyclophosphamide, in which renal survival five years after a diagnosis of lupus nephritis was only 58% in black patients compared with 95% among white patients who had similar biopsy findings and treatment regimens.⁶ Until recently, little was known about the response of individuals of Asian and Hispanic backgrounds to IV Cytoxan, although recent evidence suggests that the response to cyclophosphamide among Hispanics, in particular, is poor.

Nature vs. Nurture

The inevitable question must be asked: What role do socioeconomic factors play in the observed racial and ethnic differences in pathogenesis of lupus? Can the relative differences in outcomes among white and minority patients be ascribed to such factors as barriers to obtaining care and economic factors, or are there genetic factors that predispose these individuals to more severe or treatment-resistant lupus?