The incidence and prevalence of systemic lupus erythematosus in Thrace, 2003-2014: A 12-year epidemiological study

Background We estimated the prevalence and incidence, clinical features, treatment, and prognosis of systemic lupus erythematosus (SLE) patients in the Thrace region of Turkey. Methods We retrospectively evaluated 331 patients (307 female, 24 male, mean age 38.5 years) diagnosed with SLE between 2003 and 2014. Clinical features, treatments, and response to various treatment modalities were recorded. Our hospital has been the only tertiary referral center for rheumatological diseases for a mixed rural and urban population of 620,477 people (306,036 females, 314,411 males) for more than 16 years. Results The mean annual incidence of SLE was 4.44/100,000 (females, 8.4/100,000; males, 0.6/100,000). The overall prevalence of SLE was 51.7/100,000 (females, 97.7/100,000; males, 7/100,000). Major organ involvement was present in the following percentages: neurologic involvement: 20.1%; renal involvement: 28.2%; autoimmune hemolytic anemia: 9.6%; thrombocytopenia: 14.7%. Seventeeen SLE patients (13 females, four males) died at a median follow-up of 48 months. The five-year survival was 94.5%, and the ten-year survival was 89.9%. According to Kaplan-Meier survival analysis, poor prognostic factors were: male gender (p=0.015); smoking (p=0.02); pleural involvement (p=0.011); thrombocytopenia (p=0.021); myocarditis (p=0.028); renal involvement (p=0.037); treatment with cyclophosphamide (p=0.011); and an initial high SLEDAI score (>4) (p=0.02). Lymphopenia at the time of diagnosis appeared as a favorable prognostic factor (p=0.008). Cox regression analysis revealed myocarditis (OR: 20.4, p=0.018) and age at diagnosis (OR: 1.11, p=0.035) to be poor, and lymphopenia at the time of diagnosis to be good prognostic factors (OR:0.13, p=0.031). Conclusions The annual incidence and prevalence of SLE in the Thrace region of Turkey is lower than those reported in North America, however they are similar to those reported for European countries. Clinical manifestations appear to be milder, whereas survival was similar to those recorded in Western countries.