MULTIPLE-SCLEROSIS IN ISLAND POPULATIONS - PREVALENCE IN THE BAILIWICKS OF GUERNSEY AND JERSEY

The aim of this study was to establish for the first time the prevalen ce of multiple sclerosis in the Bailiwicks of Guernsey and Jersey, as representing the most southerly part of the British Isles. Ah patients with multiple sclerosis in the Channel Islands resident on prevalence day were identified by contacting all medical practices, Multiple Scl erosis, and Action Research for Multiple Sclerosis societies by letter and visits. The crude overall prevalence rates were 113/100 000 (95% confidence interval (95% CI) 903-1357) and 867/100000 (95% CI 63.3-110 .0) for the Bailiwicks of Jersey and Guernsey respectively. When stand ardised to the age and sex structure of a previously reported Northern Ireland population the standardised prevalence ratios were 120.2/100 000 (95% CI 96.0-144.3) for Jersey and 95.6/100 000 (95% CI 69.9-121.3 ) for the Bailiwick of Guernsey. When compared with recent studies in the northern United Kingdom the prevalence rates for multiple sclerosi s in the Channel Islands lend some support to the proposed latitudinal gradient in the British Isles although the standardised prevalence ra tio in the Bailiwick of Jersey is similar to those found in recent stu dies of southern Britain. The standardised prevalence rates of probabl e and definite multiple sclerosis for the male populations were 37.3/1 00 000 (95% CI 17.9-56.7) for the Bailiwick of Guernsey and 45.5/100 0 00 (95% CI 26.3-64.7) for the Bailiwick of Jersey whereas the standard ised prevalence rates for the female populations were 97.5/100 000 (95 % CI 73.9-143.5) and 139.5/100 000 (95% CI 112.6-181.2) respectively. Thus there is a striking and unexplained 43% higher prevalence of prob able and definite multiple sclerosis in the female population of Jerse y compared with that of the Bailiwick of Guernsey. This seems to be du e to an unusually low prevalence of the disease among the female popul ation of the Bailiwick of Guernsey compared with that of the United Ki ngdom mainland.