Validation of the PredAHT-2 prediction tool for abusive head trauma.

Objective: The validated Predicting Abusive Head Trauma (PredAHT) clinical prediction tool calculates the probability of abusive head trauma (AHT) in children <3 years of age who have sustained intracranial injuries (ICIs) identified on neuroimaging, based on combinations of six clinical features: head/neck bruising, seizures, apnoea, rib fracture, long bone fracture and retinal haemorrhages. PredAHT version 2 enables a probability calculation when information regarding any of the six features is absent. We aimed to externally validate PredAHT-2 in an Australian/New Zealand population.
Methods: This is a secondary analysis of a prospective multicentre study of paediatric head injuries conducted between April 2011 and November 2014. We extracted data on patients with possible AHT at five tertiary paediatric centres and included all children <3 years of age admitted to hospital who had sustained ICI identified on neuroimaging. We assigned cases as positive for AHT, negative for AHT or having indeterminate outcome following multidisciplinary review. The estimated probability of AHT for each case was calculated using PredAHT-2, blinded to outcome. Tool performance measures were calculated, with 95% CIs.
Results: Of 87 ICI cases, 27 (31%) were positive for AHT; 45 (52%) were negative for AHT and 15 (17%) had indeterminate outcome. Using a probability cut-off of 50%, excluding indeterminate cases, PredAHT-2 had a sensitivity of 74% (95% CI 54% t o89%) and a specificity of 87% (95% CI 73% to 95%) for AHT. Positive predictive value was 77% (95% CI 56% to 91%), negative predictive value was 85% (95% CI 71% to 94%) and the area under the curve was 0.80 (95% CI 0.68 to 0.92).
Conclusion: PredAHT-2 demonstrated reasonably high point sensitivity and specificity when externally validated in an Australian/New Zealand population. Performance was similar to that in the original validation study.
Trial Registration Number: ACTRN12614000463673.
Competing Interests: Competing interests: AMK and LEC are part of the team that derived and validated the Predicting Abusive Head Trauma tool. However, all data collection and analyses were undertaken independently of either of these authors.
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