Validation of the Overt Behaviour Scale (OBS): Measuring Challenging Behaviours following Acquired Brain Injury (ABI) in Community Settings
The Overt Behaviour Scale (OBS) quantifies a broad range of the challenging behaviours observed in the community after ABI. Extending the Overt Aggression Scale (OAS), the OBS combines 5 new subscales (sexual behaviour, inappropriate social behaviour, repetitive behaviour, absconding, adynamia) with the original 4 OAS scales which measure verbal and physical aggression. Multiple behaviours can be rated for severity, frequency and impact scores, and a total score. This study assessed the reliability and validity of the OBS.
Method: Interrater reliability was established by the independent rating on the OBS of the challenging behaviours of 20 community-based clients of the Liverpool Hospital Brain Injury Rehabilitation Unit (BIRU), based on interviews with key informants (BIRU staff, n=8). Test-retest reliability was evaluated a week later. To examine concurrent and discriminant validity, clients were rated on the Mayo-Portland Adaptability Inventory (MPAI), Current Behaviour Scale (CBS), and the Neurobehavioural Rating Scale - Revised.
Results: Interrater reliability and stability coefficients for the OBS total scores were strong (.94 and .79 respectively). Concurrent validity was shown as the MPAI Behaviour subscale correlated with the OBS total score (.60) and the following OBS subscales: Inappropriate Social Behaviour (.46); Physical Aggression against Objects (.52); and Adynamia (.51). The CBS Loss of Drive factor correlated with OBS Adynamia (.57), and CBS Loss of Emotional Control with the OBS Physical Aggression against People subscale (.54). All correlations were statistically significant. Discriminant validity was proven by the lack of correlation between the OBS total score and the remaining MPAI subscales that do not measure challenging behaviour.
Conclusions: The OBS is a reliable and valid tool for the systematic assessment of challenging behaviours in community settings, providing a means to evaluate the efficacy of management interventions.