Background The prevalence of Sjögren's syndrome (Ss), both primary and secondary, varies from 0.1% to 0.6% in European Union countries . The prevalence of Ss has been studied in Belarus neither in population nor in systemic connective tissues diseases.
Objectives To estimate prevalence of primary Sjögren's syndrome (pSs) in urban population of Belarus and frequency of secondary Sjögren's syndrome (sSs) in rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and systemic sclerosis (SS) patients in long-term observational study.
Methods To estimate prevalence of pSs we have conducted the pilot epidemiological study with the analysis of the medical aid appealability data for the five-year period (2001-2005) in the service area of 12th Minsk municipal outpatient clinic. The adult population size at the end of 2005 averaged at 51344 (27748 women and 23596 men at the age above 18 years old). In addition we have studied the frequency of sSs in 590 RA patients (482 women and 108 men), 235 SLE (213 and 22) and 89 SS patients (68 and 21), hospitalized into the rheumatology department of 9th Minsk clinical hospital in 1981-1996 and further observed at Republican rheumatologic center up to 2005 inclusive. RA, SLE, SS, Ss were diagnosed according to the ARA criteria [2-9]. 95% confidence interval (CI95) of Ss frequency was calculated by Wilson method, odds ratio (OR) was estimated by fourfold table and its two-sided statistical significance - by Fisher exact test (p2-t).
Results In the pilot epidemiological study pSs was diagnosed in 6 women of 27748 lived in the area mentioned. The cumulative prevalence of pSs among women was 0.02% (CI95 0.01-0.05%) and adjusted for age prevalence (11381 women above 55 years old) – 0.05% (CI95 0.02-0.12%). 235 RA patients, 16 SLE and 15 SS patients were revealed in this study. sSs was diagnosed in 17 women with RA (7.2%; 4.6-11.3%) and in none of SLE and SS patients. In another retrospective clinical study sSs was diagnosed in 49 RA patients (8.3%; CI95 6.3-10.8%). The frequency of sSs was 10.0% (7.6-13.0%) in women and 0.9% (0.2-5.1%) in men with RA. The same frequency of sSs was determined in SS patients (10.1%; 5.4-18.1%) and was 8.8% (4.1-17.9%) in women and 14.3% (5.0-34.6%) in men with SS. The frequency of sSs in SLE patients was significantly lower (2.6%; 1.2-5.5%) and was 2.3% (1.0-5.4%) in women and 4.5% (0.8-21.8%) in men with SLE.
Conclusions The general number of Ss patients (pSs and sSs, all - women) was 23. Therefore Ss prevalence in women was 0.08% (CI95 0.06-0.12%). We revealed distinct sexual dimorphism in sSs development in RA patients – risk of sSS in women with RA was significantly higher than in men: OR=11.8 (CI95 2.0-68.6; p2-t=0.0036). It should be also noted the higher frequency of sSS in men with SS than in men with RA – 14.3% and 0.9% correspondingly (p2-t=0.0136).
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Disclosure of Interest None declared