Using International Classification of Diseases, 10th edition, codes to estimate abusive head trauma in children.

Passive surveillance using ICD codes for hospital discharges has been used to estimate the incidence of abusive head trauma (AHT) utilizing ICD-9-CM, but not ICD-10, codes. There have been no incidence estimates of AHT in Canada where ICD-10 codes have been used since 2002. The Discharge Abstract Database from the Canadian Institute of Health Information (CIHI) for 2002-2007 was used for analyses conducted in 2011. A case was defined by code combinations that indexed injury specificity (narrow or broad) and degree of certainty (presumptive or probable) that the injury was inflicted. Estimated incidences for the populations at risk in those aged <12 months and 12-23 months from 2002-2007 were determined. For those aged <12 months, the mean incidence for "narrow, presumptive" AHT was 13.0 (95% CIs=11.3, 14.9) per 100,000 person-years; for "broad, probable" it was 15.5 (13.6, 17.6) per 100,000 person-years. For those aged 12-23 months, the "narrow, presumptive" incidence was 2.4 (1.7, 3.3) and the "broad, probable" incidence was 2.8 (2.0, 3.8) per 100,000 person-years, respectively. Month and year of age patterns were similar to previous reports. ICD-10 codes can be used to estimate incidence of AHT. Narrower classifications provide estimates consistent with those from other surveillance programs in Canada and internationally.