Disability and mortality in multiple sclerosis in western Norway

Area of Science:

• Epidemiology
• Neurology
• Public Health

Background:

• Understanding the geographical and temporal variations in multiple sclerosis (MS) frequency is crucial for identifying potential causative factors.
• Longitudinal studies of MS trends in specific populations can offer valuable insights into disease etiology.

Purpose of the Study:

• To investigate temporal trends in multiple sclerosis (MS) incidence, mortality, and disability pension rates in Møre and Romsdal County, Norway.
• To assess the significance of observed trends and differentiate between genuine increases in MS and improvements in diagnostic practices.

Main Methods:

• Analysis of age-adjusted rates of disability pension incidence, mortality, and MS incidence from 1966 to 1991.
• Utilized three semi-independent data sources for comprehensive trend examination.
• Compared county-specific MS disability pension prevalence rates with national data.

Main Results:

• Statistically significant increases observed in average annual age-adjusted disability pension incidence (3.62 to 7.33 per 100,000) and mortality rates (0.91 to 1.88 per 100,000).
• A notable increase in MS incidence rates (4.22 to 5.02 per 100,000) was also recorded.
• Discrepancies in MS disability pension prevalence trends between the county and the nation were highlighted.

Conclusions:

• The observed increases in MS incidence, mortality, and disability pension rates are considered biologically significant.
• While improved case ascertainment and diagnostics contribute partially, they do not fully explain the reported rise in MS in western Norway.
• The findings underscore the need for continued epidemiological surveillance of MS to understand its causes.