The mortality rates for multiple sclerosis in Italy (1969-1987).

The mortality for multiple sclerosis in Italy was analyzed for the period 1969-1987. The age-adjusted (to Italian 1981 population) death rates decreased slightly during these years for both sexes. The average national female/male ratio of the age-adjusted rates is 1.33 and shows a north-south gradient, with values < 1 in the South-Islands area where multiple sclerosis cases are probably heavily underreported on the death certificates. A positive, significant correlation between the age-adjusted death rates and latitude of the 20 Italian regions exists for the period 1969-1975; in recent years (1981-1987), these parameters show a weaker, but not statistically significant positive correlation. Moreover, the 95% confidence intervals of the death rates in the 20 regions overlapped extensively in both periods studied (1969-1975 and 1981-1987). Death rates for multiple sclerosis are a weak index of the frequency of the disease and their utility is restricted to national surveys. The descriptive epidemiological data (incidence, prevalence, mortality) available at present in Italy do not seem to support a link between multiple sclerosis and latitude.