Henoch Schonlein purpura in children: an epidemiological study among Dutch paediatricians on incidence and diagnostic criteria.

Background: The aim of the present study on the occurrence of Henoch-Schönlein Purpura (HSP) in Dutch children is to give some insight into the epidemiology of HSP in the Netherlands, to record the diagnostic criteria used by Dutch paediatricians and to evaluate the accuracy of the latter using the presence of IgA in the skin when biopsies are available.

Methods: Each month in 2004, all Dutch paediatricians received an electronic card asking them to mention new diagnosed HSP. Paediatricians reporting one or more new patients with HSP were sent a list of questions concerning various parameters.

Results: 232 patients from 0 to 18 years of age (6.1/10(5)) were reported as having contracted HSP in 2004. 29% presented renal symptoms. In accordance with the classification criteria of the American College of Rheumatology, 80% of paediatricians consider that isolated purpura (without haematological abnormalities) is sufficient to allow the diagnosis of HSP in children. From the 17 skin biopsies performed, only 9 (53%) presented IgA deposits. The follow-up duration, considered as necessary, was longer in case of renal symptoms at presentation. However, 45% of patients without renal symptoms would be followed for more than 1 year.

Conclusion: Considering the recent (2006) EULAR/PReS endorsed consensus criteria for the classification of childhood vasculitides, HSP should have been diagnosed in only 160 of the 179 patients of our study. The use of isolated non-thrombocytopenic purpura as the only criterion to diagnose HSP in children might therefore lead to over diagnosis and unnecessary follow-up.