[Henoch-Schönlein purpura, patients admitted to Landspítali-University Hospital 1984-2000.]

Henoch-Schönlein purpura is a disease of small vessels which primarily affects children. The epidemiology of Henoch-Schönlein purpura in Iceland is not known. The main purpose of the study was to find out the incidence of the disease in Iceland and gather further epidemiological information.

All patients diagnosed with Henoch-Schönlein purpura during the years 1984-2000 and were admitted to the Children's Hospital Iceland, Landspítali Hringbraut as well as the paediatric department at the Landspítali Fossvogi were included in the study cohort. Information was gathered from medical records. The temporal relationship between the incidende of Henoch-Schönlein purpura and epidemics of three common infectious diseases was explored.

A total of 101 patients were found to have Henoch-Schönlein purpura, 51 females and 50 males. The incidence of Henoch-Schönlein purpura in Iceland is therefore approximately six cases annually. The mean age at diagnosis was 5.4 years. In addition to the rash, 72.3% had arthralgia and 45.5% abdominalia, 36.6% had hematuria or proteinuria during the hospitalization and 5.9% had severe renal involvement. The disease was more common in the winter months (Nov. - April) compared to the summer months (May - Oct.) (p=0.045).

The epidemiology of Henoch-Schönlein purpura in Iceland is comparable to other countries. The disease was most common in children aged 2-5 years, which could reflect a common infection in the community as a part of the pathogenesis. Older children may have antibodies against these infections resulting in a decreased incidence of the disease. Our results support the theory that infection may play an important role in the pathogenesis of Henoch-Schönlein purpura. However, some abnormalities or variations in the immune response are probably also involved.