Changing epidemiology of intussusception in Australia.

Objectives: Oral rotavirus vaccines are expected to become available in Australia within the next 2 years. In light of evidence for an association between a rotavirus vaccine and intussusception, it is important to define the baseline epidemiology of intussusception in Australia and establish a system for intussusception surveillance in the immediate post-licensure period. This study reports on incidence and epidemiology of intussusception in Australia.

Methods: Data were obtained from the Australian Institute of Health and Welfare on all patients with a discharge diagnosis of intussusception from public and private hospitals in each state and territory of Australia from 1994 to 2000. We examined age at presentation, sex, month and year of presentation, indigenous status and clinical outcomes. The incidence of intussusception was calculated and annual trends examined. Surveillance data on rotavirus gastroenteritis hospitalizations over the same time period were also obtained to compare seasonal patterns.

Results: From 1994 to 2000, a 39% reduction in intussusception incidence in infants aged <1 year was observed in Australia (13.1/10,000 to 8.1/10,000; P < 0.001). The incidence of intussusception was lower in indigenous infants (3.3/10,000 <1 year) compared to non-indigenous infants (10.4/10,000 <1 year; P < 0.001). There was no association between the seasonality of rotavirus infection and intussusception. Only one of 12 deaths due to intussusception was reported in an infant <1 year.

Conclusions: This study documents the epidemiology of intussusception in Australia from 1994 to 2000 and provides important baseline information for future rotavirus vaccines. A lower risk of intussusception was identified in indigenous compared to non-indigenous infants.