Trends in the use of administrative codes for physical abuse hospitalizations

Administrative data from health care systems are important resources in the research of physical child abuse, such as tracking its incidence. Validation studies of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) for the identification of abuse cases among hospitalized children demonstrated reasonably good sensitivity (73.5%) and specificity (92.4%), despite that ICD-9-CM codes captured some cases in which abuse was only suspected. The ICD-9-CM abuse codes (all ICD codes prefixed with 995.5) made no declaration for diagnostic certainty. However, the US transition to International Statistical Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM), on October 1, 2015, allowed for new designations of suspected abuse (all ICD codes prefixed with T76) and confirmed abuse (all ICD codes prefixed with T74), which may have consequences in coding practices and subsequently the ascertainment of abuse hospitalizations. Demonstrating stability in the use of administrative coding for abuse hospitalizations would support research efforts to continue with ICD-10-CM. Conversely, a finding of instability would suggest a need for new validation studies. Our objective was to investigate trends in the use of administrative codes for abuse hospitalizations across the transition from use of ICD-9-CM codes to use of ICD-10-CM codes.