Prevalence of systemic sclerosis in a French multi-ethnic county

Objective. To assess the prevalence of systemic sclerosis (SSc) in a French multi-ethnic population and to examine ethnic differences. Methods. This survey was conducted in Seine-Saint-Denis County, a suburb of Paris, home to 1,094,412 adults (greater than or equal to15 yr), among whom 26% are of non-European background with mainly northern and sub-Saharan African, Asian and Caribbean ancestries. The study period comprised the entire calendar year 2001. Patients were ascertained through four sources: public and private hospitals, general practitioners and community specialists, the French SSc patient support group, and the National Public Health Insurance System database. Only cases meeting either the 1980 ACR and/or LeRoy and Medsger's classification criteria were included and assigned to three clinical subsets: limited (normal skin) (l), limited cutaneous (lc) or diffuse cutaneous (dc) SSc. Capture-recapture (CR) analyses using log-linear modelling were performed to correct for incomplete case finding. Results. We retained a total of 119 patients with SSc, including 15 extrapolated from inaccessible files. CR analysis estimated that 54.2 additional cases were missed by all the sources. The overall SSc prevalence (per million adults) was 158.3 (95% confidence interval, 129-187); those of lSSc, lcSSc and dcSSc were, respectively, 32.3 (16-48), 83.1 (66-101) and 42.9 (25-60); and respective values for Europeans and non-Europeans were 140.2 (112-170) and 210.8 (128-293). Conclusion. Regarding the heterogeneity of previously published estimates, this population-based survey using CR analysis might contribute to obtaining a better appraisal of SSc prevalence. Despite overlapping confidence intervals, the higher prevalence observed for non-Europeans could support potential influences of ethnic origin on the pathogenesis of SSc.