To determine which combinations of clinical features assist in distinguishing abusive head trauma (AHT) from nonabusive head trauma.
Individual patient data from 6 comparative studies of children younger than 3 years with intracranial injury were analyzed to determine the association between AHT and combinations of apnea; retinal hemorrhage; rib, skull, and long-bone fractures; seizures; and head and/or neck bruising. An aggregate analysis of data from these studies used multiple imputation of combined clinical features using a bespoke hotdeck imputation strategy, which accounted for uncertainty arising from missing information.
Analyzing 1053 children (348 had AHT), excluding nonsignificant variables (gender, age, skull fractures), for a child with an intracranial injury and 1 or 2 of the 6 features, the positive predictive value (PPV) of AHT varies from 4% to 97% according to the different combinations. Although rarely recorded, apnea is significantly associated with AHT (odds ratio [OR]: 6.89 [confidence interval: 2.08–22.86]). When rib fracture or retinal hemorrhage was present with any 1 of the other features, the OR for AHT is >100 (PPV > 85%). Any combination of 3 or more of the 6 significant features yielded an OR of >100 (PPV for AHT > 85%).
Probabilities of AHT can be estimated on the basis of different combinations of clinical features. The model could be further developed in a prospective large-scale study, with an expanded clinical data set, to contribute to a more refined tool to inform clinical decisions about the likelihood of AHT.
Comments
Beware Spectrum Bias in Estimating Abuse Probability
I wish to congratulate the authors of "Estimating the Probability of Abusive Head Trauma: A Pooled Analysis" (Vol 128(3) Sept 2011) for conducting a thorough and interesting review of the literature on Abusive Head Trauma (AHT) over the last decade.
I read their article with interest, and I certainly agree with the broad conclusion that retinal hemorrhages, rib fractures and each of the other identified red flags identified by the author are very concerning for abuse.
With that said, I want to add a note of caution about using the odds ratios published by the authors, especially in the manner suggested by Figure 2, or, as suggested by the authors, as an aid to testimony in civil or criminal proceedings.
Because there is rarely a gold-standard by which to determine if a child either has, or has not been the victim of abuse, the authors understandably sought to eliminate cases in the middle ground, where there was some concern for abuse, but abuse could not be confirmed or refuted. In doing so, however, they have created a substantial spectrum bias.
A child with a history of a short fall who is found to have a few retinal hemorrhages but no other injury, is unlikely to meet criteria as either definitely abused, or definitely not abused, and is therefore unlikely to be included in the sample tested by the authors. In the course of real-world abuse evaluations, cases such as these, where there is some concern for abuse but where it cannot be confirmed, are all too common. By systematically excluding such cases, there is a risk of artificially inflating the significance of retinal hemorrhages, and indeed all the findings tested by the authors. If one were to test only patients and nurses in a cancer hospice, alopecia might seem to be 100% specific for cancer, but applying such a test would be unwise.
While each feature identified by the authors is certainly concerning for abuse, applying odds ratios as suggested by the authors does not seem warranted at this time.
Conflict of Interest:
I have provided paid expert witness testimony for both prosecution and defense in cases of alleged child abuse.