Mortality of multiple sclerosis in Spain: demonstration of a north-South gradient

Abstract

Objective: To analyse the geographical distribution of multiple sclerosis in Spain from 1975 to 1998.

Methods: Age-adjusted mortality rates by province were obtained by the indirect method using the whole Spanish population as the reference. Then, standardised mortality ratios (SMRs) and their 95% confidence intervals were estimated.

Results: For both men and women, provinces with SMRs higher than the mean tended to be in the northern third of Spain, whilst those with SMRs lower than the mean were mostly located in the southern half. A linear regression analysis showed a significant positive association between mortality and latitude.

Conclusion: A north-south gradient in age-adjusted multiple sclerosis mortality exists in Spain.