The prevalence of multiple sclerosis in the north?west Italian province of Genoa

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The objective of this study was to assess the prevalence of multiple sclerosis (MS), calculated as point prevalence on 31 December 1997, in the province of Genoa, North-western Italy. The province of Genoa is located in North-western Italy, an area of 1,835 km(2). On the point prevalence day the population consisted of 913,218 inhabitants. MS cases were identified by analysing archives of the hospitals with neurological or rehabilitation wards, neurologists serving the community, files of local chapters of the Italian MS society, all requests for oligoclonal bands analysis on CSF in the studied area. Patients included in the study were MS cases diagnosed before 31 December 1997 according to the Poser criteria resident in the province under study. A total of 857 subjects were alive and residing in the province of Genoa on the prevalence day. The overall crude prevalence rate was 94 per 100,000 (95% CI 88-100); 291 were males (34%) with a crude prevalence of 67 per 100,000 (95 % CI 60-76) and 566 were females (66%) with a prevalence of 118 per 100,000 (95% CI 108-128). The female/male ratio was 1.9. When age and sex were adjusted to the Italian standard population of 1991 prevalence was 85 per 100,000. Five hundred and thirty two out of the 857 patients agreed to be interviewed. The interviewed sample was representative of the prevalence sample: sex and gender distributions were identical in the two samples. The overall mean age was 48 (+/-13) years (48 +/-12 years in males; 48+/-14 years in females). Mean disease duration was 15 (+/-10) years for males and 16 (+/-11) years for females. Two hundred and ninety one (55 %) subjects had a relapsing remitting (RR) clinical course, 150 (28%) were secondary progressive (SP) and 91 (17%) were primary progressive (PP). Mean EDSS score was 5 (+/- 2; median 5). The mean age at time of onset was 33 (+/-10) years for males and 32 (+/- 11) years for females. The disease onset was monosymptomatic in 76% (n=407) patients and polysymptomatic in 24% (n=125). The mean length of time between clinical onset and diagnosis was 5 (+/- 6) years. We confirmed that the province of Genoa is a very high risk area for MS. We found a high rate of patients with a PP course; also the proportion of patients with high disability scores is greater compared to previous studies.