Intussusception incidence among infants in the UK and Republic of Ireland: a pre-rotavirus vaccine prospective surveillance study.

Introduction: Intussusception, an abdominal emergency in young children, has been linked to a previous vaccine used to prevent rotavirus gastroenteritis. Although this vaccine was withdrawn, recent studies have suggested a potential, very small increased risk of intussusception following the administration of newly developed rotavirus vaccines. We aimed to determine the baseline incidence of intussusception among infants in the UK and Republic of Ireland - prior to the imminent introduction of the rotavirus vaccine into the UK schedule this year.

Methods: Prospective, active surveillance via the established British Paediatric Surveillance Unit (BPSU) was carried out from March 2008 to March 2009. Clinicians across 101 National Health Service (and equivalent) hospitals, including 27 paediatric surgical centres, reported cases admitted for intussusception in the UK and Republic of Ireland. The standard Brighton Collaboration case definition was used with only definite cases included for incidence estimation.

Results: The study response rate was 94.5% (379 questionnaires received out of 401 case notifications). A total of 250 definite cases of intussusception were identified. The annual incidence among infants in the UK and Republic of Ireland was 24.8 (95% CI: 21.7-28.2) and 24.2 (95% CI: 15.0-37.0) per 100,000 live births. In the UK, the highest incidence occurred in Northern Ireland (40.6, 95% CI: 21.0-70.8), followed by Scotland (28.7, 95% CI: 17.5-44.3), England (24.2, 95% CI: 20.9-27.9), then Wales (16.9, 95% CI: 6.8-34.8). In England, regional incidence was highest in London and lowest in the West Midlands. By age, the highest incidence (50.3/100,000 live births, 95% CI: 33.4-72.7) occurred in the fifth month of life (for England). A seasonal trend in the presentation of intussusception was observed with the incidence significantly (p=0.001) increased during winter and spring.

Conclusion: The baseline rates obtained in this study will inform rotavirus vaccine-safety policy by enabling comparison with post-introduction incidence.