Juvenile arthritis - Who gets it, where and when? A review of current dataon incidence and prevalence

Epidemiological studies of chronic arthritis in childhood can provide clues to genetic determinants of disease manifestations and environmental trigge rs. Available data are difficult to compare, however, because of the hetero geneity of the disease, differences in the classification criteria used for definition and inclusion, and differences in source populations and case a scertainment. Nevertheless, when the data are interpreted according to the methodologies used, geographical and ethnic differences can be found with r egard to occurrence rates, age at onset, subgroup distribution and immunolo gical markers. Seasonal variations have been detected in systemic disease. Variations in the incidence of childhood arthritis over time have also been observed, indicating environmental influences on disease frequency, while familial aggregations suggest the presence of genetic factors. These epidem iological data form a challenging puzzle which we hope will provide clues t o future understanding of etiologies and cures, with the help of basic scie ntific research.