Background Epidemiologic studies have described clinical characteristics of patients with systemic lupus erythematosus (SLE) in Middle Eastern Asia and Western countries and marked ethnic and geographic differences in the prevalence, severity and outcome of SLE have been reported. However, data from Northeast Asia countries including South Korea are lacking.
Objectives To investigate demographic, clinical, laboratory and immunological characteristics and prognosis of patients with SLE in South Korea.
Methods We retrospectively evaluated 413 SLE patients (380 female, 33 male, mean age 40.6 years) diagnosed at 3 tertiary rheumatology centers in South Korea from 1992 to 2016 by reviewing medical chart. All patients fulfilled 1997 revised American College of Rheumatology classification criteria for SLE and were ethnically Korean.
Results The mean (±SD) age at disease diagnosis was 30.9 (±12.8) years and the median (IQR) disease duration was 108 (60–168) months. The commonest clinical manifestations in our patients were arthritis (59.1%), fever (49.9%), malar rash (48.4%), alopecia (43.8%) and oral ulcer (35.1%). The frequency of major organ involvement was as follows: biopsy-proven lupus nephritis (40.7%), neuropsychiatric involvement (19.4%), secondary anti-phospholipid antibody syndrome (6.1%) and lupus pneumonitis (1.7%). Class IV (41.1%) was the most common type of lupus nephritis followed by class V (15.5%). Regarding hematologic abnormalities, the cumulative incidence of leucopenia was 74.3%, thrombocytopenia 46.5%, lymphopenia 45.1% and hemolytic anemia 8.7%. Antinuclear antibodies were detected in 97.8%, anti-Sm in 38.4%, anti-dsDNA IgG in 56.5%, anti-cardiolipine IgG in 27.4%, anti-cardiolipine IgM 11.8%, lupus anticoagulant in 23.2%, anti-Ro in 62.3%, anti-La 30.2% and anti-RNP in 47.9%. Twenty (4.8%) patients died during median follow-up of 84 months and the 5-year and 10-year survival rates were 96.9% and 95.5%, respectively (Figure 1). The major causes of death were infection (35%) and diffuse alveolar hemorrhage (20%). In multivariable Cor regression models, male (HR=8.68, p<0.001), age at diagnosis ≤16 years (HR=3.33, p=0.033), serositis (HR=3.04, p=0.018) and thrombocytopenia (HR=3.23, p=0.041) were associated with poor survival, while SLE patients with hydroxychloroquine use showed better survival (HR=0.11, p=0.001).
Conclusions Compared with data from other countries, the higher prevalence of hematologic manifestatons and positive anti-Ro antibody were prominent feature of South Korean SLE patients. Overall survival rate in our patients was better than that in other populations.
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Disclosure of Interest None declared