Potential severity of aggressive behaviour after acquired brain injury: implications for recording.

Aggression is a consequence of acquired brain injury that may necessitate admission to neurobehavioural services. The 'Overt Aggression Scale - Modified for Neurorehabilitation' (OAS-MNR) is a valid, reliable means of capturing this. A criticism of observational rating scales is they do not reflect factors like intent to harm which results in recording anomalies. 'Attacks' has been proposed as a measure which achieves this within psychiatric settings. Principal goals of this study are to determine the usefulness of measuring similar concepts in neurobehavioural services and further validating both scales. A total of 1066 physical assaults were recorded in 6 weeks by 25 patients in an inpatient neurobehavioural programme using the OAS-MNR. Fifty incidents were also rated on Attacks. Convergent validity for using both measures in neurobehavioural services was found. Modifying OAS-MNR severity scores using one of two factors found to underlie Attacks produced an index that successfully discriminated incidents whose risk necessitated more intrusive intervention, which was not evident otherwise. Modifying scores that objectively reflect severity of physical assaults using measures of perceived intent should be a feature of observational recording scales such as the OAS-MNR. Ensuring robust inter-rater reliability will be essential in any development work.