Objective Population-based health surveys are increasingly popular sources of data on injury occurrence. Self-reported surveys can yield estimates of the total incidence of non-fatal injuries while simultaneously capturing a rich repository of contextual data that may be informative for exploring determinants of injury risk. Although survey data are rarely recognised as complete, several researchers have expressed concerns about the sensitivity and validity of self-reported injury data, questioning whether captured cases are representative of the population experience of injury, particularly among children and youth. The present study sought to compare the population incidence of paediatric injury estimated from self-reported survey responses to those documented by a complete-capture health service utilisation database among Ontario children.

Methods Injury incidence rates documented from the National Longitudinal Survey of Children and Youth and the National Population Health Survey were compared with those reported in Canada's National Ambulatory Care Reporting System for Ontario youth aged 0–19 years for fiscal year 2002/3, stratified by the child's age and geographical location of residence.

Results The two self-reported health surveys underestimated the population incidence of injury among Ontario children by at least 49% and 53%, respectively. Systematic errors exist in survey data capture such that injuries in infants and preschoolers (<4 years of age) and urban residents were most likely to be missed by the population health surveys.

Conclusion Injury incidence estimated through self-report is not representative of the population burden and experience of paediatric injury for Ontario children, and may produce biased estimates of risk when analysed as independent sources of data.