The prevalence and incidence of systemic lupus erythematosus in children and adults: a population-based study in a mountain community in northern Italy

OBJECTIVES: To estimate prevalence and incidence of systemic lupus erythematosus (SLE) in paediatric and adult populations in Italy. METHODS: The study was carried out in Valtrompia, a valley in northern Italy, where a relatively close community lives, in 2009-2012. The only referral centre for SLE in the area is the Rheumatology Unit of the University Hospital of Brescia. The ascertainment of SLE cases was performed through the integration of three sources: 1) hospital database; 2) database of the Rheumatology laboratory; 3) database of general practitioners and general paediatricians practicing in the area. Each patient was evaluated by a rheumatologist for confirmation of SLE classification based on the presence of at least 4 criteria according to the American College of Rheumatology. RESULTS: Forty-four SLE patients (39 females, 89%) were identified. The prevalence of SLE at 31st December 2012 was 39.2 (95% C.I. 28.5-52.6) cases per 100,000 individuals in all subjects, and 42.3 (30.5-57.2) and 15.3 (1.8-55.1) in adults and children, respectively. Nine new cases of SLE were diagnosed over the 4 years of the study period, with an annual incidence rate of 2.0 (0.9-3.8) per 100,000 individuals. CONCLUSIONS: This is the first study estimating the prevalence and incidence of SLE in Italy in both adult and paediatric population. Prevalence and incidence rates in line with those reported in other Mediterranean European countries. The accurate assessment of the SLE frequency is supported by the choice of a well-defined area, the integration of multiple data sources and the revision of each case by a rheumatologist.