Motor symptoms in 100 patients with delirium versus control subjects: Comparison of subtyping methods

Background: Different motor presentations of delirium may represent clinically meaningful subtypes. Objective: Authors sought to evaluate delirium phenomena. Method: They used three non-validated delirium psychomotor subtype schemas, applied to a palliative-care population. Their unique items were merged to comprise a 30-item Delirium Motor Checklist (DMC) used to collect data, rate each schema, and determine subtype frequencies in 100 consecutive DSM-IV delirium patients and 52 medically-matched control subjects without delirium. The Delirium Rating Scale-Revised-98 (DRS-R98) assessed delirium severity, and subtype categorization using its two motor items was compared with the scale that used the psychomotor schema. Results: In delirium, motor disturbance was present in 100% by DMC versus 92% by DRS-R98 motor items; the DMC motor items also significantly distinguished delirium from control subjects. Motor subtype classification (hyperactive, hypoactive, mixed, and none) varied among the four methods, with low concordance across all four methods and 76% concordance for pairwise comparisons. The DRS-R-98 identified the most hypoactive delirium cases. Conclusion: Motor disturbances are common in delirium, although whether they represent clinical subtypes is confounded by methodological issues. New motor subtyping methods are needed that are validated in other medical populations, use matched control subjects, and have higher sensitivity and specificity for pure motor features.