Delirium and exposure to psychoactive medications in critically ill adults: A multi-centre observational study.

Purpose: Investigate the relationship between psychoactive drugs and delirium.

Materials And Methods: Prospective observational study of 520 critically ill adult patients admitted ≥24h to 6 intensive care units (ICUs). Data were collected on psychoactive drug exposure, use of sedation administration strategies, and incident delirium (Intensive Care Delirium Screening Checklist score≥4).

Results: Delirium was detected in 260 (50%) patients, median (IQR) duration 2 (1-5) days, and time to onset 3 (2-5) days. Delirious patients received more low-potency anticholinergic (P<0.0001), antipsychotic (P<0.0001), benzodiazepine (P<0.0001) and non-benzodiazepine sedative (P<0.0001), and opioid (P=0.0008) drugs. Primary regression (24-hours preceding drug exposure) revealed no association between any psychoactive drug and delirium. Post-hoc analysis (extended 48-hour exposure) revealed an association between delirium and high-potency anticholinergic (HR 2.45, 95% CI 1.08-5.54) and benzodiazepine (HR 1.08 per 5mg midazolam-equivalent increment, 95% CI 1.04-1.12) drugs. Delirious patients had longer ICU (P<0.0001) and hospital (P<0.0001) length of stay, and higher ICU and hospital mortality (P=0.003 and P=0.007, respectively).

Conclusions: The identification of psychoactive drugs as modifiable delirium risk factors plays an important role in the management of critically ill patients. This is particularly important given the burden of exposure and combinations of drugs used in this vulnerable patient population.