Clinical Features Associated with Delirium Motor Subtypes in Older Inpatients: Results of a Multicenter Study.

Objective: To date motor subtypes of delirium have been evaluated in single-center studies with a limited examination of the relationship between predisposing factors and motor profile of delirium. We sought to report the prevalence and clinical profile of subtypes of delirium in a multicenter study.

Methods: This is a point prevalence study nested in the "Delirium Day 2015", which included 108 acute and 12 rehabilitation wards in Italy. Delirium was detected using the 4-AT and motor subtypes were measured with the Delirium Motor Subtype Scale (DMSS). A multinomial logistic regression was used to determine the factors associated with delirium subtypes.

Results: Of 429 patients with delirium, the DMSS was completed in 275 (64%), classifying 21.5% of the patients with hyperactive delirium, 38.5% with hypoactive, 27.3% with mixed and 12.7% with the non-motor subtype. The 4-AT score was higher in the hyperactive subtype, similar in the hypoactive, mixed subtypes, while it was lowest in the non-motor subtype. Dementia was associated with all three delirium motor subtypes (hyperactive, OR 3.3, 95% CI: 1.2-8.7; hypoactive, OR 2.8, 95% CI: 1.2-6.5; mixed OR 2.6, 95% CI: 1.1-6.2). Atypical antipsychotics were associated with hypoactive delirium (OR 0.23, 95% CI: 0.1-0.7), while intravenous lines were associated with mixed delirium (OR 2.9, 95% CI: 1.2-6.9).

Conclusions: The study shows that hypoactive delirium is the most common subtype among hospitalized older patients. Specific clinical features were associated with different delirium subtypes. The use of standardized instruments can help to characterize the phenomenology of different motor subtypes of delirium.