Quetiapine Twice Daily Versus Bedtime Dosing in the Treatment of ICU Delirium

Background: Although guidelines recommend twice daily (BID) dosing of quetiapine for treatment of intensive care unit (ICU) delirium in most patients, once daily dosing at bedtime (HS) is commonly prescribed to reduce daytime somnolence. No studies have evaluated differences in outcomes. Objectives: To determine if twice daily vs bedtime dosing of quetiapine reduces the duration of ICU delirium. Methods: Retrospective analysis of ICU patients treated with twice daily vs bedtime dosing of quetiapine for ICU delirium. Health records were analyzed between January 1, 2017, and December 31, 2021. Exclusions included alcohol withdrawal, history of psychiatric conditions requiring medication, receipt of <24 hours of therapy, alternative dosing schedules, and death or transfer from the ICU <24 hours after beginning quetiapine. The primary outcome was recovery of delirium per Confusion Assessment Method (CAM-ICU). Secondary outcomes included lengths of stay, mechanical ventilation duration, in-hospital death, and QTc prolongation. Results: Baseline characteristics differed for sex (30.4% vs 61.1% female) and admission diagnosis (39% vs. 17% COVID-19, respectively). Time to delirium recovery was 3.5 days for BID vs 2.5 days for QHS dosing (P = .484). Secondary outcomes of ICU (16 vs. 19 days) and hospital (22 vs. 25 days) lengths of stay, duration of mechanical ventilation (10 vs. 14), delirium recovery (70% vs. 56%), in-hospital death (61% vs. 50%), and QTc prolongation did not differ significantly between groups. Conclusions: Twice daily vs bedtime dosing of quetiapine did not significantly alter delirium outcomes, suggesting similar efficacy. Larger sample sizes are needed to confirm these results.