Comprehensibility in Measurement of Neurobehavioral Function in Disorders of Consciousness: Integrating Data Visualization and Change Indices for the Coma/Near-Coma Scale.

Abstract

Objective: To apply a comprehensible, person-centered measurement principle to the reporting of the 8-item Coma/Near-Coma Scale (CNC-8), a measure of neurobehavioral function (NBF) for patients with disorders of consciousness. We developed Rasch equal-interval measures and change indices on a 0-100 equal-interval scale to support comprehensibility and applied data visualization techniques to enhance transparency for interpreting change in CNC-8 measures over time.

Design: Secondary data set using the partial credit Rasch measurement model and a case example.

Setting: Post-acute care rehabilitation.

Participants: Participants (N=40) with disorders of consciousness after a severe brain injury.

Interventions: Not applicable.

Main outcome measures: CNC-8.

Results: We transformed CNC-8 raw total scores to 0-100 equal-interval measures so that lower values indicated less NBF and higher values indicated more NBF. Indices of responsiveness, including minimal detectable change (MDC) of 15 units and conditional MDC, ranged from 16-62 units.

Conclusions: Conditional MDCs provide a more precise method for examining NBF change; however, without an electronic approach to data visualization, a single MDC is easier and quicker to apply in clinical practice. Person-centered measurement emphasizes the need for assessment results that are comprehensible to all relevant parties, including clinicians and family care partners. Integration of Rasch equal-interval measures, change indices, and modern data visualization techniques can facilitate comprehensibility of interpreting CNC-8 assessment results in real time at the bedside.