Sex- and age-specific incidence of autoimmune rheumatic diseases in the Chinese population: A Taiwan population-based study

Objectives: The purpose of this study was to estimate the sex- and age-specific incidence rates of major autoimmune rheumatic diseases (ARDs) in Taiwan using a population longitudinal database. Methods: A health insurance database containing the records of 1,000,000 beneficiaries of Taiwan National Health Insurance from 2005 to 2009 was used. Results: Between 2005 and 2009, the overall incidence rate of the major ARDs was 29.8 (95% CI = 28.3-31.3) per 100,000 person-years. Among the ARDs studied, the incidence of rheumatoid arthritis (RA; per 100,000 person-years) was highest (17.2, 95% CI = 16.1-18.4) and was followed by Sjogren's syndrome (11.8, 95% CI = 10.8-12.7), systemic lupus erythematosus (SLE; 7.2, 95% CI = 6.5-8.0), systemic sclerosis (SS; 1.1, 95% CI = 0.8-1.4), vasculitis (1.0, 95% CI = 0.7-1.3), Behcet disease (0.9, 95% CI = 0.6-1.1), dermatomyositis (DM; 0.7, 95% CI = 0.5-1.0), and polymyositis (PM; 0.6, 95% CI = 0.4-0.8). Females had a higher incidence ratio than did males, but a significant female/male incidence ratio was only observed for SLE (8.5, 95% CI = 6.1-12.0), Sjogren's syndrome (6.0, 95% CI = 4.8-7.6), RA (3.0, 95% CI = 2.6-3.5), and SS (2.6, 95% CI = 1.4-4.6). Conclusions: ARDs are three to four times more common among women than among men in the Chinese population of Taiwan. The incidence of RA was the highest followed by Sjogren's syndrome and SLE, while the incidence of Behcet disease was the lowest in this study. This nationwide, population-based, longitudinal epidemiological study of ARDs in Taiwan provides data for future global comparisons and may provide clues as to the etiology of these diseases. (C) 2013 Elsevier Inc. All rights reserved.