Possible increasing risk of multiple sclerosis in Catania, Sicily

To update prevalence and incidence rates of multiple sclerosis (MS) in Catania, Italy during 1990 to 1999 and evaluate their temporal profiles to assess a possible increase in the MS risk in our study population.

We studied the frequency of MS in Catania, Italy (population of 313,110 as reported in the 2001 census). The primary sources for the case ascertainment were the neurologic and motor-rehabilitation departments, the MS centers, the Italian MS Association, private neurologists, and family doctors. We considered as prevalent and incident cases all patients who satisfied Poser's criteria for clinically definite MS (CDMS), laboratory-supported definite MS (LSDMS), clinically probable MS (CPMS), and laboratory-supported probable MS (LSPMS).

We found 288 subjects with MS who had onset of disease before December 31, 1999 (prevalence day) in a population of 313,110 inhabitants. The prevalence rate was 92.0/100,000 (95% CI 81.8 to 103.2) and was higher in women (102.4/100,000) than in men (80.4/100,000). The age-specific prevalence showed a peak in the group aged 35 to 44 years (208.2/100,000). From 1990 to 1999, 155 patients with MS had the clinical onset of the disease. The mean annual incidence was 4.7/100,000 (95% CI 4.0 to 5.5). Age-specific incidence showed a peak in the group aged 25 to 34 years (11.7/100,000). Mean annual incidence for 5-year intervals increased from 3.9/100,000 during 1990 to 1994 to 5.5/100,000 during 1995 to 1999.

Prevalence and incidence rates of multiple sclerosis have further increased during the last decade.