Background Prevalence of systemic lupus erythematosus (SLE) is an important measure for monitoring the disease, for investigating differences across populations.

Objectives We evaluated the clinical features, treatment modalities, treatment responses and prognosis of SLE patients diagnosed at our center in Thrace region of Turkey. We also estimated prevalence and incidence of SLE in our region.

Methods We retrospectively evaluated 331 patients (304F, 27M, mean age: 38.5±12.3 years) diagnosed with SLE between 2003-2014. Clinical features, treatments and responses 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 620477 people for >16 years (306036 females, 314411 males).

Results Of 331 SLE patients, 307 (92.7%) were females and 24 (7.3%) were males (female/male: 12.8). During the study period, the mean annual incidence rate of SLE was 4.44/100,000 (95%CI: 2.78-6.1). The mean annual incidence of SLE in women was 8.4/100,000 (95%CI: 5.2-11.6), and in men it was 0.64/100,000 (95%CI: 0-1.52). By November 2013, the overall prevalence of SLE in our region was 51.7/100,000 (95%CI: 46-57.4) in population aged >16 years. The prevalence in women (97.7/100,000, 95%CI: 86.6-108.8) was higher than the prevalence in men (7/100,000, 95%CI: 4.1-9.9). Major organ involvement was present in following percentages: renal involvement, 28.4%; neurologic involvement, 18.7%; thrombocytopenia, 15.1%; and autoimmune hemolytic anemia, 13.9%.

Seventeen SLE patients (14 females, 3 males) died at a median follow-up of 48 months (2-278 months). The 5-year survival was 94.5%, and the 10-year survival was 89.9%. According to Kaplan-Meier survival analysis, poor prognostic factors were being male (10-year: 80.9% vs. 90.6%, p=0.05); smoking (10 year, 78.2% vs. 94.1, p=0.02); thrombocytopenia (10-year: 76.9% vs. 93.2%, p=0.021), pleural involvement (10-year: 74.9% vs. 93.4%, p=0.011); renal involvement (10-year: 85.6% vs. 92.9%, p=0.037); myocarditis (10-year: 71.4% vs 91.1, p=0.028); an initial SLEDAI score >4 (10-year: 85.8% vs 93.8%, p=0.02) and the usage of cyclophosphamide (10-year: 81.7% vs. 94.7%, p=0.011). Lymphopenia at the time of diagnosis seemed to be a good prognostic factor according to Kaplan-Meier analysis (10-year: 94.6% vs. 80.6%, p=0.008).

According to multivariate Cox regression analysis, myocarditis (OR: 20.4, 95%CI: 1.9-200, p=0.12), and age at diagnosis (OR: 1.11, 95%CI: 1.008-1.23, p=0.035) were independently poor prognostic parameters; lymphopenia at the time of diagnosis (OR: 0.13, 95%CI: 0.02-0.82) was a good independent prognostic factor.

Conclusions Our study demonstrated that the annual incidence and prevalence of SLE in Thrace region of Turkey were lower than in North America, however, they were similar to European data. Survival was similar to data from western countries.

Disclosure of Interest None declared