Incidence of XXXX in the Nordic countries. A population based study with special reference to the validity of the ILAR and EULAR criteria.

@entity1 @entity625 @entity66 @entity1596 @entity4932 @entity1691
OBJECTIVE: To find the incidence of @entity625 according to the ILAR and EULAR criteria within defined areas in the Nordic countries, and to study the validity of the ILAR and EULAR criteria from this perspective. METHOD: A longitudinal, prospective, population based study with @entity1 enrolled according to the ILAR and EULAR criteria. Twenty doctors in Iceland, Norway, Sweden, Denmark, and Finland collected data from the incidence cases within their catchment areas over a period of 1.5 years, beginning July 1, 1997. Clinical and serological data from the first year of the disease were collected. RESULTS: In the whole group of 315 @entity1 , the incidence rate was 15 per 100,000 @entity1 /year (95% CI 13-17) according to the ILAR criteria, varying from 7 (1-13) in Iceland, 19 (7-31) and 23 (10-36) from 2 different regions in Norway, and 9 (5-12) and 16 (9-23) from 2 different areas in Denmark, to 15 (12-18) in Sweden and 21/100,000/year (15-26) in the Helsinki region in Finland. An early peak in distribution for age of onset was found in @entity1 but not in @entity1 . The number of antinuclear antibody (ANA) positive @entity1 in the whole group, made up of @entity1 who had undergone at least one analyzed ANA test, was 123/315 (39%). @entity1 were ANA positive in 83/197 (42%) and @entity1 in 40/118 (34%). @entity1596 developed in 27/315 (8.6%) @entity1 during the first 6 months of the disease. CONCLUSION: Incidence rates of @entity625 for areas within the Nordic countries were in accord with previous data. The ILAR criteria present slightly higher incidence rates, with a @entity66 duration for inclusion, compared to the EULAR criteria. @entity1 in one subgroup in either of the criteria sets do not necessarily belong to the expected subgroup in the other set of criteria; e.g., for juvenile @entity1691 (EULAR) and @entity4932 related @entity625 (ILAR). Our epidemiological findings are a reminder to be aware of possible new subgroups in @entity1 with @entity625 .
