Objective While serious infections are significant causes of morbidity and mortality in systemic lupus erythematosus (SLE), the epidemiology in a nationwide cohort of SLE and lupus nephritis (LN) patients has not been examined. Methods Using the Medicaid Analytic eXtract (MAX) database, 2000-2006, we identified patients 18-64 years with SLE and a subset with LN. We ascertained hospitalized serious infections using validated algorithms, and 30-day mortality rates. We used Poisson regression to calculate infection incidence rates (IR), and multivariable Cox proportional hazards models to calculate hazard ratios (HR) for first infection, adjusted for sociodemographics, medication use, and a SLE-specific risk adjustment index. Results We identified 33,565 patients with SLE and 7,113 with LN. There were 9,078 serious infections in 5,078 SLE patients and 3,494 infections in 1,825 LN patients. The infection IR per 100 person-years was 10.8 in SLE and 23.9 in LN. In adjusted models, in SLE, we observed increased risks of infection among males compared to females (HR 1.33, 95% CI 1.20-1.47), in Blacks compared to Whites (HR 1.14, 95% CI 1.06-1.21), and glucocorticoid users (HR 1.51, 95% CI 1.43-1.61) and immunosuppressive users (HR 1.11, 95% CI 1.03-1.20) compared with non-users. Hydroxychloroquine users had a reduced risk of infection compared to non-users (HR 0.73, 95% CI 0.68-0.77). The 30-day mortality rate per 1,000 person-years among those hospitalized with infections was 21.4 in SLE and 38.7 in LN. Conclusion In this diverse, nationwide cohort of SLE patients, we observed a substantial burden of serious infections with many subsequent deaths.
【저자키워드】 Mortality, Epidemiology, systemic lupus erythematosus, infections, lupus nephritis,