Incidence and prevalence of juvenile arthritis in an urban population of southern Germany: a prospective study

Objective-To ascertain the incidence and prevalence of juvenile arthritis i n a German urban population. Methods-All 766 paediatricians, orthopaedists, and rheumatologists working in practices or outpatient clinics in 12 south German towns were asked to r eport all patients who consulted them for juvenile arthritis during the yea r 1995. Patients with continuing symptoms were followed up for 9-12 months to obtain a final diagnosis. Extended measures of quality control were take n to control for known biases. Results-Of 457 reported cases, 294 were diagnosed with para-/postinfectious arthritis (PPA), 78 with juvenile chronic arthritis (ICA), and IS with oth er forms of arthritis. Half of the PPA cases were classified as transient s ynovitis of the hip (SH). For JCA the reported annual incidence was 6.6 and the prevalence 14.8 per 100 000 subjects under 16 years of age. For PPA th e reported incidence was 76 and the prevalence 4.4 per 100 000 subjects und er 16. The incidence of rheumatic fever was clearly below 1 per 100 000 peo ple under 16. A correction model was used to control for known biases and t o adjust the estimates accordingly. Conclusions-The results of this first prospective study on the incidence an d prevalence of juvenile arthritis in Germany are consistent with a retrosp ective study performed in the Berlin area. Based on these results it was es timated that the annual frequency of juvenile arthritis in Germany is as fo llows: 750-900 incident JCA cases, 21 000 incident SH cases, and 21 000 inc idence cases of other forms of PPA a year. The number of incidence cases of rheumatic fever is expected to be markedly lower than 150 a year. The tota l prevalence is expected to be 3600-4350 JCA cases, 2250-3000 SH cases, and the same number of other forms of PPA.