A population sample of 2464 persons between 20 and 70 years of age was invited to participate in a screening study designed for establishing gallstone prevalence rates. The diagnosis of gallstones was based on an ultrasonographic examination. The overall response rate after the primary invitation was 55.6%. Gallbladder stones were diagnosed in 300 persons, giving a crude prevalence of 21.9%. Total age-adjusted prevalence rates were 17.7% in men and 21.2% in women. From age group 20-29 years to age group 60-69 years the prevalence rates increased from 4.9% to 37.0% in men and from 6.0% to 41.3% in women. The age- and sex-specific rates are comparable to those of more recent studies from Scandinavia but are markedly higher than prevalence rates in a Norwegian study from 1960.

– In the county of Hordaland, Western Norway, the prevalence of MS has been shown to have increased from 20/100,000 in 1963 to 60/100,000 in 1983. This study shows that the increase in prevalence was caused by a highly significant and marked increase in incidence over a 30‐year period. The average annual incidence of about 2 per 100,000 population in 1953–1962 increased to 4 per 100,000 in the period 1968–1977. The rise in incidence was parallel for both sexes until 1970. In the last 10 years, the incidence has continued to increase among females, whereas a decrease has been observed among males.

We have previously found an increase in prevalence and incidence of multiple sclerosis (MS) in the county of Hordaland, Western Norway. This study shows that the increase in incidence over a 30-year period is due to an increase of remittent and remittent/progressive MS. The incidence of the chronic progressive form of MS has remained stable during the same period. The two subgroups of MS also vary in symptomatology and age at onset. This suggests that MS has two different forms which behave differently when considered epidemiologically and clinically. The remitting and progressive forms may therefore each have a different etiology.

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