The incidence of systemic lupus erythematosus (SLE) is disproportionately high in nonwhite patients compared with white patients. However, variation in mortality according to race/ethnicity has not been well studied. The aim of this study was to examine all-cause mortality according to race/ethnicity among SLE patients enrolled in Medicaid.
We used Medicaid Analytic eXtract data, with billing claims from 47 US states and Washington, DC, to identify individuals ages 18-65 years who were enrolled in Medicaid for ≥3 months in 2000-2006. Individuals were classified as having SLE if they had ≥3 visits ≥30 days apart with an International Classification of Diseases, Ninth Revision (ICD-9) code for SLE (710.0). Among the individuals with SLE, those with lupus nephritis (LN) were identified by the presence of ≥2 ICD-9 claims for glomerulonephritis, proteinuria, or renal failure. We calculated mortality rates per 1,000 person-years, with 95% confidence intervals (95% CIs), according to race/ethnicity. Multivariable Cox proportional hazards regression models were used to estimate mortality risks, adjusting for age, sex, demographics, and comorbidities.
Among 42,221 prevalent cases of SLE, 8,191 prevalent cases of LN were identified. Blacks represented 40.1%, whites 38.4%, and Hispanics 15.3%. Overall SLE mortality rates per 1,000 person-years were highest among Native American (27.52), white (20.17), and black (24.13) patients and were lower among Hispanic (7.12) or Asian (5.18) patients. After multivariable adjustment, Hispanic and Asian patients had lower mortality risks (hazard ratio [HR] 0.48 [95% CI 0.40-0.59] and 0.59 [95% CI 0.40-0.86], respectively) compared with whites. Conversely, the risk of death was significantly higher among Native American (HR 1.40 [95% CI 1.04-1.90]) and black (HR 1.21 [95% CI 1.10-1.33]) patients compared with white patients. Among patients with LN, mortality risks were lower in Hispanic and Asian patients compared with white patients.
After accounting for demographic and clinical factors, mortality among Asian and Hispanic Medicaid patients with SLE was lower than that among black, white, or Native American patients.