Child restraint legislation and injury rate NSW 2001-2019: analysing hospital administration data.

Background: In March 2010, New South Wales (NSW), Australia, introduced legislation mandating age-appropriate restraints for child passengers up to 7 years. This study aims to evaluate its impact on child injury rates using linked hospital and death data.

Methods: An interrupted time series using random effects quasi-Poisson regression analysed hospital-admitted injury rates in child passengers (0-14 years) in NSW, Australia, from July 2001 to March 2019. Hospital administration data were divided into prelegislation, legislation and postlegislation periods, with the legislative period spanning November 2007 to December 2011, accounting for a 6-month adaptation and enforcement grace period.

Results: Injury rates in children under 14 were reduced postlegislation compared with prelegislation. The average injury rate was 33% lower for children directly affected by the legislation (aged 1-6 years, incidence rate ratio (IRR)=0.67, 95% CI: 0.57 to 0.79), 25% lower for children aged 7-10 years (IRR=0.75, 95% CI: 0.65 to 0.85) and 20% lower for children aged 11-14 years (IRR=0.80, 95% CI: 0.68 to 0.94). Compared with children aged 11-14, the injury rate for other age groups decreased, though with large uncertainty in these estimates.

Conclusions: The findings suggest a decrease in injuries among child passengers following legislation mandating age-appropriate restraints up to 7 years. However, similar reductions among older children and substantial uncertainty in estimates using the oldest children as controls limit attribution of the effect solely to the legislation. Combined with observational studies showing increased restraint use among children under 12 years old, the results indicate an overall postlegislation improvement in child passenger safety in NSW, Australia.