Probability Calculator

What is the calculatorâ€™s purpose?

To inform your clinical decisions to either launch or forego an abuse evaluation.

How should the AHT probability calculator be used?

As a source of additional data that will help you make an optional decision. It will be important to remember that some acutely head-injured children with low estimates of abuse probability might still need a workup for abuse. Conversely, some acutely head-injured children with high estimates of abuse probability might not have been abused.

When should the AHT probability calculator be applied?

At or near the time of admission to the PICU, when initial history, physical examination, and head imaging studies are complete.

For which patients can the calculator be applied?

For children under 3 years of age hospitalized for intensive care of acute, closed, traumatic, head injuries confirmed by initial CT or MR imaging. The probability calculator should not be applied to patients with pre-existing brain malformation, disease, infection, or hypoxia-ischemia; or to patients with head injuries resulting from collisions involving a motor vehicle.

How does the AHT probability calculator work?

Clinicians answer four questions, and the calculator returns an evidence-based, patient-specific, estimate of the probability of abuse.

How accurate are the calculator's patient-specific estimates of abuse probability?

The estimates are based solely on analysis of the 500 patients in our combined derivation and validation study datasets, where the overall prevalence of AHT was 44%. In PICUs with a higher prevalence of AHT, the actual probability of abuse is likely higher. In PICUs with a lower prevalence of AHT, the actual probability of abuse is likely lower. Some unique combinations of the calculator’s four predictor variables occurred very infrequently. For these patients, the confidence intervals surrounding the estimate of abuse probability are quite wide.

What additional information is available that might help clinicians make such decisions?

We can also provide information about the diagnostic yield of abuse evaluations observed in equivalent patients who *were* evaluated for abuse.

How was abusive head trauma defined during the development of this AHT probability calculator?

By applying a priori definitional criteria. For more information, select this link.