OBJECTIVE: To study the incidence of Systemic Lupus Erythematosus (SLE) in the city of Natal, Brazil. METHODS: Only patients living in the city of Natal, older than 15 years old, who fulfilled at least 4 of ACR criteria between January 1st, 2000 and December 31st, 2000, were included. Four sources were used to identify new cases of SLE: 1) the University Hospital; 2) "health units" and hospitals of the public health network; 3) specialists at private hospitals and outpatient clinics; 4) three laboratories performing antinuclear antibody (ANA) determination. Physicians were contacted by mail, receiving explanations about the study and directions on how to collaborate. Brazilian population census data (2000) was used to calculate incidence rate. The Standardized Mortality Ratio (SMR) was used to compare the incidence rates. The 95% confidence intervals (95% CI) were calculated and a P value < 0.05 was considered statistically significant. RESULTS: Forty three patients were diagnosed as SLE new cases in 2000. The calculated incidence was 8.7/100 000/year (95% CI 6.3-11.7). Thirty eight patients were female 14.1/100.000/year (95% CI 10.0-19.3) and 5 were male 2.2/100.000/year (95% CI 0.7-5.2). The mean age of SLE new cases was 31.8 years old (95% CI 27.8-35.8). The mean age for women was 31.4 years old and for men it was 35.0 years old. The median of disease duration (time between onset of the first ACR criterion for SLE and diagnosis) was 10 months (1-72 months). CONCLUSIONS: The incidence of SLE in Natal is apparently higher than those reported in other regions of the world. The observed differences may be due to ethnical and/or environmental factors.
systemic lupus erythematosus; incidence; Brazil; epidemiology
