JUVENILE CHRONIC ARTHRITIS IN URBAN SAN-JOSE, COSTA-RICA - A 2-YEAR PROSPECTIVE-STUDY

Objective. To find the incidence and prevalence of juvenile chronic ar thritis (JCA) in the urban area of San Jose, Costa Rica. Methods. Duri ng the year preceding our 2 year prospective, population based study, we conducted an educational program on JCA. The physicians caring for children < 16 years of age from all centers in the study area followed the program. They were asked to refer all cases of possible JCA accor ding to EULAR criteria. The children were all evaluated at the Nationa l Children's Hospital. Results. Of 189 children referred, 48 fulfilled EULAR criteria for JCA. The 2 year incidence rare for JCA was 13.7 pe r 100,000 children < 16 years old. This corresponds to an annual incid ence per 100,000 children of 6.8 (95% CI 4.1-9.6). The incidence rate for pauciarticular onset JCA was 3.9 per 100,000. At the prevalence da te, 122 cases of JCA were recorded, corresponding to a prevalence of 3 4.9 per 100,000 children < 16 years. When patients in remission were e xcluded, the prevalence was 31.4 per 100,000 (95% CI 25.5-37.2). The p auciarticular onset form was the most common, 71% of all prevalence ca ses. The highest incidence and prevalence were noted for pauciarticula r girls with late onset JCA. No incidence peak was found in preschool age. The girl-to-boy ratio was 1.5/1. Antinuclear antibodies (ANA) wer e positive in only 7 cases (6.3%). IgM rheumatoid factor was found in 13 children (10.6%). Chronic iritis was observed in 4 cases, all of th em ANA negative and older than 7 years of age at onset of arthritis. C onclusion. The incidence and prevalence observed were lower than those reported in other population based studies, but within the confidence intervals of their data. The incidence rate for pauciarticular JCA wa s significantly lower than that reported in other comparable studies, ANA positive pauciarticular preschool girls and associated uveitis wer e rarely encountered.