The feasibility of assigning severity to injuries coded in ICD-10-AM

Road safety research relies on information about the severity of injuries to casualties involved in different crash situations. Policy evaluation uses this information indirectly through costing methods that are based on the severity of injury to specific body regions. Although ICD-10-AM is now used extensively in Australia and New Zealand, no direct mapping of injuries coded in ICD-10-AM to the Abbreviated Injury Severity scoring system (AIS-90) has yet been developed. The objective of this paper is to demonstrate the feasibility (or otherwise) of using existing severity scoring software for ICD-9-CM and locally developed mapping tables from ICD-10-AM to ICD-9-CM. The ICD-10-AM classification system introduced major changes to the way injuries are recorded. The details of the nature of the injury are more precise and several codes may be used to describe the different components of one injury. This makes the task of mapping codes from ICD-10-AM to ICD-9-CM problematic. In Western Australia, a decision tree approach has been taken to systematically examine the list of injury codes in each casualty record, to isolate sets of codes describing a particular injury and then assign a corresponding ICD-9-CM code of similar severity. The injury severity distributions of road crash casualties derived from ICD-9-CM and ICD-10-AM diagnosis codes will be used to evaluate the mapping process. (a) For the covering entry of this conference, please see IRRD abstract no. E202589.