USE OF ICD-9-CM CODES IN THE ESTIMATION OF ALCOHOL-INVOLVED INJURY - SEARCH FOR A SURROGATE .2

This study presents a follow-up analysis of 22,427 injury cases drawn from the California Regional Trauma Registry. Whereas the earlier anal ysis developed a surrogate for alcohol-involved injuries using E-codes as reflective of injury type, this analysis explores the possibility of using ICD-9-CM diagnosis codes that have a longer history and are a vailable in more jurisdictions. Findings reported herein indicate that the original demographic patterns predicting testing and alcohol invo lvement patterns were maintained in ICD-9-CM diagnostic code-based mod els. Moreover, although variables representing demographic background, time of day, and day of week clearly were the most powerful model pre dictors, ICD-9-CM diagnostic codes reflecting physician assessment tha t the patient had a chronic alcohol problem did improve the fit of mod els, and thus provide additional information concerning testing and bl ood alcohol concentration patterns. In contrast, ICD-9-CM diagnostic c odes reflecting the specific nature of the injury, although statistica lly significant, explained little additional variability in alcohol in volvement. Nevertheless, the overall model did accurately classify sim ilar to 75% of those in the sample for whom blood alcohol concentratio n status information was available, suggesting its appropriateness for surrogate development.