BACKGROUND: Epidemiologic data for multiple sclerosis in Nordland County in Norway has not been recorded for more than 50 years. MATERIAL AND METHODS: Cases between 1970 and 1999 were identified by diagnostic code searches in the files of Nordland Central Hospital, the county's only hospital with a department of neurology. Several cases from Nordland were also identified in hospital files in neighbouring counties. RESULTS: The raw prevalence of multiple sclerosis was determined to be 105.6 per 100,000 as at December 31, 1999. The crude annual incidence in the 1970-1999 period was 3.6 per 100,000 (95 % CI: 3.1-4.0). There was a pronounced rise in incidence from the late 1970s up until the early 1980s. From 1985 to 1999, the average annual incidence rate has been stable at 5.1 per 100,000 (95 % CI: 4.4-5.8). INTERPRETATION: Compared to other Norwegian counties for which there are epidemiologic data, Nordland represents a medium risk zone for multiple sclerosis. The increase in incidence from the late 1970s to the early 1980s is most likely due to improved diagnosis and better record-keeping.
BACKGROUND: Epidemiologic data for multiple sclerosis in Nordland County in Norway has not been recorded for more than 50 years. MATERIAL AND METHODS: Cases between 1970 and 1999 were identified by diagnostic code searches in the files of Nordland Central Hospital, the county's only hospital with a department of neurology. Several cases from Nordland were also identified in hospital files in neighbouring counties. RESULTS: The raw prevalence of multiple sclerosis was determined to be 105.6 per 100,000 as at December 31, 1999. The crude annual incidence in the 1970-1999 period was 3.6 per 100,000 (95 % CI: 3.1-4.0). There was a pronounced rise in incidence from the late 1970s up until the early 1980s. From 1985 to 1999, the average annual incidence rate has been stable at 5.1 per 100,000 (95 % CI: 4.4-5.8). INTERPRETATION: Compared to other Norwegian counties for which there are epidemiologic data, Nordland represents a medium risk zone for multiple sclerosis. The increase in incidence from the late 1970s to the early 1980s is most likely due to improved diagnosis and better record-keeping.