Epidemiology of juvenile idiopathic arthritis in Alsace, France

To determine the incidence, prevalence, and principal characteristics of the different forms of juvenile idiopathic arthritis (JIA) in the region of Alsace, northeastern France, using the new classification of the International League of Associations for Rheumatology (ILAR).

In 2002 we performed a retrospective epidemiologic study pertaining to the year 2001. The pediatricians, rheumatologists, ophthalmologists, orthopedic surgeons, and physicians involved in functional reeducation in the Alsace region were interviewed, and all patients were classified according to the new ILAR classification using the criteria revised in Durban in 1997.

Among the 361 clinicians contacted, the participation rate was 97.8%. The study identified 67 children followed for JIA in Alsace in 2001, from a total population of 1.8 million inhabitants including 339,095 children under age 16 years. The incidence was calculated to be 3.2 cases/100,000/year and the prevalence 19.8 cases/100,000 children under age 16 years. Among these 67 cases of JIA, the most frequent forms were oligoarthritis (n = 27, 40.3%), polyarthritis without rheumatoid factor (RF; n = 15, 22.4%), and enthesitis related arthritis (n = 12, 17.9%). Other forms, notably systemic arthritis (n = 6, 8.9%) and psoriatic arthritis (n = 3, 4.5%), were more rare and in this study there was no case of polyarthritis with RF. Only 4 patients (6%) were classified in the undifferentiated arthritis group using the new classification. Antinuclear antibodies (ANA; by indirect immunofluorescence, HEp >/= 1/80) were detected in patients with oligoarthritis (81%) and polyarthritis without RF (79%). Uveitis occurred in 41% of children with oligoarthritis and in 14% of those with polyarthritis without RF.

Our results are comparable to those of other studies carried out in Caucasian populations with regard to incidence and prevalence. This work also highlights the frequent presence of ANA and uveitis in patients with oligoarthritis or polyarthritis without RF.