sus (SLE) was carried out at 9 university centers diverse in geographic, socioeconomic, and racial characteristics. The mortality and disease characteristics of the patients at study entry varied widely among centers. The survival rates from the time patients with a diagnosis of SLE were first evaluated at the participating center was 90% at 1 year, 77% at 5 years, and 71% at 10 years. Patients with a serum creatinine >3 mg/dl at study entry had the lowest survival rates: 48%, 29%, and 12% at 1, 5, and 10 years, respectively. Survival rate also correlated independently with the entry hematocrit, degree of proteinuria, number of preliminary American Rheumatism Association criteria for SLE satisfied, and source of funding of medical care. When data were corrected for socioeconomic status, race1 ethnic origin did not significantly influence survival. Survival rates varied widely at different participating institutions, generally due to differences in disease severity. Place of treatment was independently associated with survival only in the second year after study entry. Disease duration before study entry did not account for the differences in disease severity.Reports of prognosis in systemic lupus erythematosus (SLE) from single medical centers are often not comparable because of differences in the characteristics of patient populations. Because of these differences, there has been disagreement about the natural history and clinical course of SLE. Attempts to analyze literature trends (1) and to pool data from several centers (2) have provided some insights. In order to test the reliability of these insights and to assess more accurately which factors determine sur-60 1

Data from a prospective study of the clinical course in 223 patients with systemic lupus erythematosus followed for 655 patient-years were analyzed by computer to determine the influence on frequency of infection of 1) corticosteroid dose; 2) azathioprine; 3) active disease, measured by new disease exacerbations, elevated ESR, hypocomplementemia, active urinary sediment, and proteinuria; 4) uremia; and 5) leukopenia. The frequency of all infections, and of bacterial and opportunistic infections specifically, increased progressively with increasing steroid dose. Azathioprine use, independent of steroid dose, did not account for an increased risk of bacterial, opportunistic, or nonspecific viral infections. Leukopenia did not predispose to infection, except possibly when associated