Prevalence of multiple sclerosis in a south London borough.

A survey of multiple sclerosis in the London Borough of Sutton, population 169,600, yielded 195 cases, giving an overall prevalence of 115/100,000. This is the third highest prevalence for a first survey of a geographical area in the United Kingdom, exceeded only by 127/100,000 in north east Scotland and 134/100,000 in Shetland. On the classification system of Allison and Millar, three quarters of the cases were classified as probable multiple sclerosis, 15% as early probable and latent multiple sclerosis, and 10% as possible multiple sclerosis. The mean age was 49 years, the mean age at onset was 34 years, and the mean duration of the disease was 15.4 years. The age standardised female to male ratio was 2:1. The prevalence found in this survey does not differ significantly from that recorded in the first north east Scotland survey. This study suggests that, firstly, the prevalence of multiple sclerosis in south east England is probably about 100/100,000 and, secondly, the latitudinal effect on the prevalence of multiple sclerosis in the United Kingdom is less appreciable than previously believed.