Regional variations in the prevalence rates of multiple sclerosis in the province of Alberta, Canada.
Multiple sclerosis (MS) prevalence rates were examined for the fiscal years 1984/1985-1988/1989, in the province of Alberta, Canada, by age, sex and census division. Data were derived from the health care records of individuals registered with the Alberta Health Care Insurance Plan which requires registration by all residents of the province (approximately 2.4 million). The overall crude prevalence rate was 216.7 per 100,000 (173.1 for males; 260.3 for females) population. Females had a significantly higher prevalence (p < 0.05) and the rates were highly correlated between the sexes (r = 0.94, p < 0.01). The present study confirms other studies finding a high prevalence rate within the province of Alberta. The prevalence rate for Alberta is among the highest reported in the world indicating that the province appears to be an excess risk area relative to other global locations. Also, the results indicate that MS is unevenly distributed throughout the province which offers support for the involvement of environmental factors related to the onset of this disorder.