Tryptophan supplementation and postoperative delirium--a randomized controlled trial.

OBJECTIVES: To determine whether the postoperative administration of tryptophan would be beneficial for elderly adults undergoing surgery who are at risk of developing postoperative delirium.

DESIGN: Randomized, double-blind, placebo-controlled trial.

SETTING: Denver Veterans Affairs Medical Center.

PARTICIPANTS: Individuals aged 60 and older undergoing major elective operations requiring a postoperative intensive care unit (ICU) admission (n = 325).

INTERVENTION: L-tryptophan, 1 g orally three times a day or placebo was started after surgery and continued for up to 3 days postoperatively.

MEASUREMENTS: Delirium and its motor subtypes were measured using the Confusion Assessment Method-Intensive Care Unit (CAM-ICU) and the Richmond Agitation and Sedation Scale. The primary outcome for between-group comparison was the incidence of excitatory (mixed and hyperactive) postoperative delirium. The secondary outcomes for comparison were the incidence and duration of overall postoperative delirium.

RESULTS: The overall incidence of postoperative delirium was 39% (95% confidence interval = 34-44%) (n = 116). Seventeen percent of participants in the tryptophan group and 9% in the placebo group had excitatory delirium (P = .18), and the duration of excitatory delirium was 3.3 ± 1.7 days for tryptophan and 3.1 ± 1.9 days for placebo (P = .74). Forty percent of participants in the tryptophan group and 37% in the placebo group had overall delirium (P = .60), and the duration of overall delirium was 2.9 ± 1.8 days for tryptophan and 2.4 ± 1.6 days for placebo (P = .17).

CONCLUSION: Postoperative tryptophan supplementation in older adults undergoing major elective operations requiring postoperative ICU admission did not reduce the incidence or duration of postoperative excitatory delirium or overall delirium.