Prevalence of scleroderma spectrum disorders in the general population of Estonia

The purpose of this study was to estimate the prevalence of scleroderma spectrum disorders (SDS) in the general population of Estonia while taking into account environmental and ethnic factors. A random sample of 14,467 subjects from the general population were surveyed by mail questionnaire to detect those with suspected Raynaud phenomenon (RP) and SDS. A subsample of 2,154 participants was then seen during the field study to confirm the RP diagnosis and to perform a short clinical examination. Of 581 subjects with RP, 13 cases (all women) were diagnosed as having SDS; based on these findings, the estimated prevalence of SDS in the adult population is 228 per 100,000 (95% CL 121; 391), while in women alone it is 354 per 100,000 (95% CL 188; 605). The best estimate of SD (systemic scleroderma), based on ACR criteria, is 35 per 100,000 (95% CL 4; 127). No significant difference in SDS prevalence was found between the two environmentally different regions we studied. Although statistically not significant, the prevalence of SDS, especially of SD and CREST syndrome, among Russians was higher than among Estonians, as we had hypothesized. The distribution of SDS subtypes also suggests an ethnic difference. The overall prevalence of SD/CREST that we found is higher than that reported in studies not based on a random sample of the general population.