Objective To compare admission rate, cumulative incidence and social distribution of potentially preventable hospitalisations (PPHs) among children according to the current Australian adult definition, and the child definition developed in New Zealand.

Design, setting, participants Deidentified, linked public hospital, births registry and perinatal data of children aged 0–10 years born 2002–2012 in South Australia (n=1 91 742).

Main outcome measures PPH admission rates among 0–10 year olds and cumulative incidence by age 5 under the adult and child definitions. Cumulative incidence was assessed across indicators of social and health disadvantage.

Results PPH admission rates among 0–10 year olds were 25.6 (95% CI 25.3 to 25.9) and 59.9 (95% CI 59.5 to 60.4) per 1000 person-years for the adult and child definitions, respectively. Greater absolute differences in admission rates between definitions were observed at younger ages (age <1 difference: 75.6 per 1000 person-years; age 10 difference: 1.4 per 1000 person-years). Cumulative incidence of PPHs among 0–5 year olds was higher under the child (25.0%, 95% CI 24.7 to 25.2) than the adult definition (12.8%, 95% CI 12.6 to 13.0). Higher PPH incidence was associated with social and health disadvantage. Approximately 80% of the difference in admission rate between definitions was due to five conditions.

Conclusions Respiratory conditions and gastroenteritis were key contributors to the higher PPH admission rate and cumulative incidence among children when calculated under the child definition compared to the adult definition. Irrespective of definition, higher PPH cumulative incidence was associated with social and health disadvantage at birth.