Estimating the Prevalence of Systemic Sclerosis in the Lorraine Region, France, by the Capture-recapture Method

Objective: To assess the prevalence of systemic sclerosis (SSc) in the Lorraine region, France. Methods: Data from three sources - general practitioners and community and hospital specialists, medical records departments, and regional and national laboratories-and a capture-recapture method with log-linear models were used to estimate SSc prevalence in the region. Double recording was checked, and reported cases were validated after a review of medical records. Results: We identified 560 records of suspected SSc cases corresponding to 327 unique suspected SSc cases existing on June 30, 2006, in Lorraine. On the basis of the 193 validated cases (22 [11.4%] with diffuse disease; 136 [70.5%] with limited disease, 31 [16.1%] with limited involvement and 4 unknown), the observed overall crude prevalence of SSc was 105.4 cases per million adult inhabitants (95% confidence interval [CI]: 91.0; 121.4). With the capture-recapture method, the estimated number of SSc cases was 233 (95% CI: 217.3; 260.0), so an estimated 40 cases were not identified by the three sources. The estimated overall prevalence was 132.2 cases per million adult inhabitants (95% CI: 115.8; 154.0). Conclusions: Our study provides the first estimate of SSc prevalence in the Lorraine region. The capture-recapture method allowed us to estimate an additional 21% of unobserved cases and is a good alternative to the community-based study design for estimating the prevalence of rare diseases. (C) 2013 Elsevier Inc. All rights reserved. Semin Arthritis Rheum 42:530-538