Infections and related risk factors of arthritis in children. A case-control study.

We used a parent-completed questionnaire to record the clinical signs of infection preceding the onset of joint symptoms by 1 month or less in 334 children with arthritis or other joint disease. An upper respiratory tract infection (URTI) often preceded the onset of arthritis (51%) but also arthralgia (56%) and even trauma or orthopedic disease (43%). The results of a case-control analysis of 165 patients and community controls matched for age and sex were in favour of a preceding URTI having an etiologic or triggering role in acute transient arthritis of other joints than the hip only (odds ratio of preceding URTI, 7.0), juvenile rheumatoid arthritis (odds ratio 3.3) and transient synovitis of the hip (odds ratio 3.0). The form of day-care differed significantly from that of controls only in patients with transient synovitis of the hip who attended a day-care centre more often than controls (odds ratio 3.5).