Predictors of increasing injury severity across suspected recurrent episodes of non-accidental trauma: a retrospective cohort study.

BACKGROUND: Little is known about how the severity of injury changes with recurrent events of suspected non-accidental trauma (NAT). Our objective was to determine risk factors for escalating severity of injury in children with multiple events of suspected NAT.

METHODS: This retrospective longitudinal cohort study included children from a pediatric Medicaid accountable care organization with ≥ 1 non-birth related episode containing an International Classification of Diseases, Ninth Revision, Clinical Modification or Current Procedural Terminology code for NAT or a skeletal survey between 2007 and 2011. Subsequent potential NAT events were defined as independent episodes with codes for either NAT, a skeletal survey, or injuries suspicious for abuse. Severity of injury was calculated using the New Injury Severity Score (NISS). Multivariable Cox proportional hazards regression modeling was used with results expressed as hazard ratios and 95 % confidence intervals.

RESULTS: Of the 914 children with at least one suspected NAT event, 39 % had at least one suspected recurrent NAT event; 12 % had 2 events and 5 % had ≥ 3 events during follow-up. Factors associated with an increased risk for a recurrent episode of suspected NAT with higher NISS were living in a rural area (1.69, 1.02-2.78, p = 0.04) and having an open wound (2.12, 1.24-3.62, p = 0.006), or superficial injury (2.28, 1.31-3.98, p = 0.004). In contrast, a greater number of injuries was associated with a decreased risk for a recurrent episode of suspected NAT with higher NISS (p < 0.0001).

CONCLUSIONS: Though limited by a lack of follow-up of children placed in out of home care, our results suggest that children with "minor" or less numerous injuries are either not reported to child protective services or not removed from the unsafe environment with either situation leading to subsequent events. The medical and child welfare systems need to better identify these potential victims of recurrent events..