Assessing functional communication in patients emerging from a disorder of consciousness: Impact of task and stimuli on response accuracy

Objective To explore how task and stimuli influence response accuracy in assessing functional communication in adults emerging from a Prolonged Disorder of Consciousness (PDOC). Setting Specialist post-acute brain injury assessment centre. Subjects Twelve adults (7 male; 5 female) emerging from PDOC, recruited consecutively between June 2021 and August 2023. Methods A prospective study exploring the impact of task and stimuli on response accuracy. Yes/no questions and spoken word-to-referent (colour/object) matching tasks were presented. Stimuli were controlled for psycholinguistic variables to reduce linguistic confounds in the assessment of consciousness. Accuracy was compared to a standard measure (visually based situational yes/no questions from the Coma Recovery Scale-Revised). Results Responses were most accurate for word-to-referent matching tasks compared to yes/no questions ( t (23) = −6.49, P < 0.001, d = 1.33), with greater accuracy to colour than object stimuli ( t( 23) = 2.79, P = 0.01, d = 0.57). Participants also responded with greater accuracy to word-to-referent matching and yes/no questions involving colours and objects compared to the Coma Recovery Scale-Revised situational yes/no questions. Conclusion Task influences accuracy of responses in assessing return of consciousness. The advantage of colours over objects can be attributed to simpler visual processing and higher lexical frequency of these words. The current standard situational yes/no tasks from the Coma Recovery Scale-Revised resulted in lowest scores and should not be relied upon as the only measure of functional communication.