Incidence and prevalence of systemic lupus erythematosus in a district of North Italy

The objective of this study was to investigate the incidence and the prevalence of systemic lupus erythematosus (SLE) in an area of northeast Italy. We retrospectively examined all patients of 16 years and older of native Italian origin and resident in Ferrara district either admitted to hospital or referred to our outpatient clinic with a diagnosis of SLE determined between 1 January 1996 and 31 December 2002. SLE subjects were identified both by a search of hospital discharge code 710.0 according to the international classification of diseases- 9 codes, and using a computerized search for this pathology code in the national health care system. Incidence and prevalence rates were calculated as number of cases per 100 000 inhabitants. Population data were based on the 2002 National Census. A total of 299 cases of SLE were identified. After a review of all cases by one experienced investigator, 98 were excluded because did not satisfied the 1982 revised criteria of the American College Rheumatology. Therefore, 201 patients had a definite diagnosis of SLE. The prevalence of SLE in the district was 57.9/100 000. The mean age at diagnosis was 41 years, the average duration of the disease from symptoms onset to diagnosis was 4.8 years and the female/ male ratio 9 : 1. Annual incidence in 2000 was 2.01/100 000, in 2001 1.15/100 000 and in 2002 2.6/100 000. This is the first study dealing with prevalence and incidence of SLE in an Italian district. Data obtained concerning prevalence, incidence, age at diagnoses and female predominance are in agreement with those published in literature.