Delirium diagnostic tool-provisional (DDT-Pro) scores in delirium, subsyndromal delirium and no delirium

Objective: To evaluate whether the Delirium Diagnostic Tool-Provisional (DDT-Pro), a 0–9 point scale with three items each representing symptoms from delirium's three core domains, differentiates subsyndromal delirium (SSD) from delirium and no delirium. Methods: We applied cluster analyses of DDT-Pro scores from 200 consecutive inpatients using three reference standards for delirium diagnosis to determine DDT-Pro cutoff values for delirium, SSD and no delirium groups. Clinical validators and DDT-Pro item scores were compared among groups. Results: DDT-Pro SSD range was 6–7 (n = 54), with no delirium having higher scores (n = 98) and delirium lower (n = 48). Dementia prevalence in the SSD group (40.7%) was intermediate between no delirium (20.4%) and delirium (66.7%). SSD and delirium groups were more affected than no delirium regarding medical comorbidities, hospital stay (no delirium <1 week, SSD and delirium >1 week) and mortality (SSD = 7.4%, delirium = 18.8%, no delirium = 1%). Values for motor subtypes, frontal lobe signs, and DRS-R98 in the SSD group were intermediate between no delirium and delirium, as well as for the DDT-Pro items (all p < 0.05). Conclusions: All DDT-Pro items, which represent the three delirium core domains, are important for SSD diagnosis. Patients scoring in the SSD 6–7 range have significant clinical and prognostic features and deserve clinical attention.