A prevalence survey of multiple sclerosis in Sussex.

A first survey of the Brighton and Mid-Downs health districts in Sussex showed a prevalence of multiple sclerosis of 111 per 100,000 (95% confidence interval (95% CI) 103-120) in a population of 596,594 on prevalence day, 1 July 1991. Cases were notified by multiple sources and to maximise case notification patients were not contacted. Cases were classified by hospital and family practitioner notes. The Poser criteria were used for classification. These criteria are precise and exclude cases of isolated spinal cord syndrome. The Allison and Millar criteria used in the surveys in Scotland may lack specificity and it is concluded that the high prevalence of multiple sclerosis in Scotland needs to be reassessed with the more precise criteria. Until this is done, the latitude effect within the United Kingdom remains not proved.