[Norwegian fibromyalgia epidemic--its rise or possible decline. What is the trend based on disability statistics?].

The Norwegian National Insurance Scheme (Folketrygden) offers universal coverage to all inhabitants between 16 and 67 years with respect to disability pension. During the 1980s, the number of new disability-pensioners increased rapidly. In 1991, 8.5% of the population at risk received this pension. So called "diffuse" conditions in the musculoskeletal system accounted for a large proportion of new cases. Myalgia/fibromyalgia became a major reason for disability pension. In 1989 more than 7% of the new cases had this diagnosis. The parliament (Stortinget) passed controversial amendments to the National Insurance Acts in 1991 and 1995 which restricted the criteria for obtaining a disability pension. At present the law demands that "a scientific concept of disease" should be applied in these matters. The numbers of new disability-pensioners decreased significantly during the period 1989-1993. The figures from 1994 and 1995 perhaps show a new upward trend, including also "diffuse" diagnoses like fibromyalgia. The use of "diffuse conditions" as a cause for disability pension is discussed in light of the official request for a scientifically justified diagnosis.