Incidence of nephrotic syndrome in Australian children

EM Hodson, NS Willis, JC Craig
for the Australian and New Zealand Paediatric Nephrology Association
through the Australian Paediatric Surveillance Unit. Centre for Kidney Research, Royal Alexandra Hospital for Children, Sydney

Introduction. The incidence of childhood nephrotic syndrome and its geographical and ethnic distribution are not well known. The Australian Paediatric Surveillance Unit (APSU) has a well established system for the prospective identification of all children with uncommon conditions achieving a 95% report rate from their monthly cards.
Methods. To determine the incidence of idiopathic and congenital nephrotic syndrome (NS) in Australia and to describe the distribution in relation to age, sex, socio-economic status, geography and ethnicity, NS has been listed on the APSU card since July 1998 and it will be listed for 3 years. Initial and one year follow up questionnaires are sent to all doctors who report a case.
Results. Between July 1998 and October 1999, 55 new confirmed cases of NS in children aged below 15 years were reported; 54 with idiopathic NS and 1 with congenital NS. The age range was 0.4 - 13.3 years (median 4.0 years). The incidence of idiopathic NS in Australia was 1.15 per 100,000 (95% CI 0.94,1.54); there were no significant differences in incidence between states ( 2 = 2.03, P = 0.66). The incidence decreased significantly with age ( 2 trend = 8.97; p = 0.0028) from 1.79 per 100,000 (95% CI 1.14, 2.69) at 0 - 4 years to 0.53 per 100,000 (95% CI 0.21,1.10) at 10-14 years; variations from the trend were not significant. The incidence of NS did not differ significantly between those children with parents of Australian origin and those children with parents of overseas origin. The small number of cases of NS reported to date do not allow meaningful interpretation of socio-economic data.
Conclusion. In this prospective Australian study the incidence of idiopathic NS appears to be lower than the reported incidence of 2 per 100,000 from retrospective studies carried out in the USA and in Europe.

Presented at the Annual Scientific Meeting of the Royal Australasian College of Physicians, Adelaide, May 2000

Correspondence
Elisabeth Hodson
ElisaH@chw.edu.au