Gold standard assessment of delirium severity in patients with dementia: Evaluation of an expert panel adjudication process

Background Patients with Alzheimer's disease and related dementias (ADRD) have an increased risk for delirium and subsequent complications. Rating delirium severity in the presence of co-occurring dementia is challenging due to overlapping features of delirium and ADRD. The multi-site prospective Better ASsessment of ILlness (BASIL)-II study will develop and validate a new delirium severity instrument for use in patients with and without ADRD. Objective Describe an expert panel process used to rate delirium severity. Methods Clinical assessors conducted standardized cognitive tests. A separate panel of experts independently reviewed assessors’ reports, rated delirium severity using a 0–10 scale, and assigned dementia diagnoses using DSM-5 criteria. Panel agreement was defined using a priori criteria. Cases without agreement after initial review were discussed as a group and re-rated using a modified Delphi approach until achieving consensus. Results Patients (N = 488) were on average 79 years old, 58% female, and 75% White. After initial review, 80% of cases were in agreement for delirium severity. Kappa was 0.86 (95% CI, 0.78, 0.82) before expert panel discussion and 0.90 (95%CI, 0.89, 0.92) after consensus. Final delirium severity ratings were no delirium (48%); subsyndromal (22%), mild-moderate (25%), or severe (6%). Disagreement in delirium severity was associated with ADRD (OR 3.02), nursing home setting (2.63), and vision impairment (2.42). Conclusions This rigorous process provides confidence that delirium severity can be rated accurately in patients with and without ADRD. We will use this expert panel adjudication to provide the reference standard for validation of a future delirium severity instrument.