Capturing the ghost in the machine: a process for development and validation of measures of phenomenal consciousness in delirium.

A set of candidate measures for assessing phenomenal consciousness in delirium has been developed and validated. Delirium is traditionally considered a disorder of consciousness, but clinical assessments of alertness and arousal are insufficient for a dimensional evaluation. A narrative review of 814 articles identified 14 existing tools across three domains of phenomenal consciousness—prereflective consciousness, phenomenal-sensed experience, and reflective thought—but only one met eligibility criteria for delirium assessment. Fifty-seven new tests were generated using the silent generation technique, later reduced to 26 and then 22 after content validity evaluation. The scale average content validity index was 0.89, inter-rater agreement ranged from 80% to 97%, and face validity was 100% positive. The Flesch Reading Ease Score was 91.6, indicating very easy readability. Early validation results are promising.

Study at a glance

Abstract

Delirium has conventionally been considered a disorder of consciousness. Alertness and arousal are used as surrogates in clinical practice but are insufficient for the purposes of a more dimensional assessment of consciousness. We present a process of development and validation of candidate measures of phenomenal consciousness that could be applied to the diagnosis of delirium. First, a narrative review of available instruments in the fields of phenomenal consciousness, including prereflective consciousness, the phenomenal-sensed experience and reflective thought, was undertaken. Eligibility of tools in the context of applicability to delirium was based upon objectivity in test interpretation and the requirement for tester administration. Second, where there was a gap in suitable cognitive tools, new items were derived using the silent generation technique. A process of face and construct validity using a diverse panel of experts was performed, and readability was evaluated. 814 articles were screened from the literature review. Fourteen candidate tools were reported from the three domains of phenomenal consciousness. One of these met the eligibility criteria for a delirium assessment. Fifty-seven new tests of phenomenal consciousness were identified. After a process of item reduction, a total of 26 individual tests were identified. After content validity, 22 of the 26 items were retained. The scale average content validity index was 0.89. The agreement between raters was between 80% and 97%. 100% of responses for face validity were rated as positive. Flesch Reading Ease Score was 91.6 (very easy to read). Candidate measures of phenomenal consciousness are described, and early validity studies are promising.