Objective. To estimate the prevalence, incidence, survival, and disease characteristics of systemic sclerosis (SSc) in the Detroit tri-county area. Methods. A census of SSc cases for the period 1989–1991 was conducted in the Detroit area, using multiple sources for case identification. Diagnoses were verified by medical record review. Capture-recapture analysis was used to estimate the total SSc population. Cases of localized scleroderma (morphea and linear disease) were excluded. Results. Based on 706 verified cases of SSc, the prevalence was initially estimated to be 242.0 cases per million adults (95% confidence interval [95% CI] 213–274), with an annual incidence of 19.3 new cases per million adults per year (95% CI 12.4–30.2). Capture-recapture analysis, based on the degree of overlap of verified cases among multiple sources, resulted in a revised prevalence estimate of 276 cases per million adults (95% CI 245–310). Sex- and race-specific prevalence estimates were significantly higher for women than for men, and for blacks than for whites. The average age at diagnosis was significantly younger for blacks than for whites. Compared with white patients, black patients were almost twice as likely to have diffuse disease (prevalence proportion ratio 1.86, 95% CI 1.48–2.35). Median survival was 11 years. Factors negatively affecting survival included male sex (hazard ratio 1.81, 95% CI 1.29–2.55) and older age at diagnosis (hazard ratio 1.04, 95% CI 1.03–1.05). Conclusion. This study establishes baseline estimates of SSc occurrence and characteristics in a large US cohort consisting primarily of black adults and white adults. These data should facilitate research regarding the role of geographic, ethnic, racial, and environmental factors for this disease in comparison populations.

Published estimates of the prevalence and incidence of systemic sclerosis (SSc; scleroderma) vary widely depending on the period of observation, methods of case ascertainment, and the geographic area of study. Reported US incidence rates vary between 2.7 cases per million per year for the time period 1947–1968 (2) and 18.7 cases per million per year for the time period 1972–1982 (6). Similarly, US prevalence estimates have varied from 138 cases per million for the period 1950–1979 (4) to 286 cases per million in 1985 (5). These discrepancies may reflect true variation in disease occurrence among different populations or may be related to methodologic differences, such as the degree of scrutiny applied or the classification of disease.

Although survival in patients with SSc has improved in the past several decades, it remains considerably diminished compared with that in age- and sexmatched populations (8–18; for review, see ref. 19). Reliable estimates of overall survival as well as survival by disease subtypes are important in order to gauge effects of new treatment modalities or to document the changing natural history of this disease. Dependable incidence, prevalence, and mortality statistics are necessary to evaluate the health impact of this disease on the population. The aim of this study was to determine the prevalence and incidence of SSc and survival rates in patients with SSc by conducting a census of all patients with SSc in the Detroit tri-county metropolitan area for the years 1989–1991. This metropolitan area, consisting of the counties of Wayne, Oakland, and Macomb, has a large overall population with a substantial black component (2.917 million adults, of whom 75.0% are white, 21.9% are black, and 3.1% are of other races [according to 1990 US census data]).

Patients were identified from the following sources: 1) the patient population of hospitals and outpatient clinics affiliated with Wayne State University/Detroit Medical Center, 2) the patient population of the University of Michigan Medical Center, 3) patients from the practices of Detroit area rheumatologists, 70% of whom participated in this study, 4) a computer search of medical records from all 55 area hospitals (including those in the counties adjacent to the tricounty area) for patients discharged with the diagnosis of SSc (International Classification of Diseases [ninth version] code 710.1 [20]), and 5) the Southeast Michigan chapter of the Scleroderma Foundation (formerly, the United Scleroderma Foundation), a patient support group.