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. Author manuscript; available in PMC: 2013 Apr 14.
Published in final edited form as: Crit Care Med. 2012 Mar;40(3):835–841. doi: 10.1097/CCM.0b013e318236f62d

Table 3.

Associations between kynurenine-to-tryptophan ratios and delirium-to-coma-free days

Variable 25th Percentile 75th Percentile Difference in Mean Delirium/Coma-Free Days (95% Confidence Interval) p
Age at enrollment 47.8 66.0 −0.6 (−1.6 to 0.3) .19
Acute Physiology and Chronic Health Evaluation II acute physiology score component 11.0 20.0 −0.4 (−1.6 to 0.8) .48
Dexmedetomidine vs. lorazepama Lorazepam Dexmedetomidine 2.1 (0.6 to 3.6) .007
Baseline kynurenine/tryptophan ratio 0.1 0.6 − 2.1 (− 3.2 to − 1.0) −.001

Linear regression was used to study the role of kynurenine/tryptophan in delirium/coma-free days after adjusting for age, severity of illness, and study drug. The difference in means represents the difference in delirium/coma-free days between patients at the 75th percentile of kynurenine-to-tryptophan ratios of our population vs. the 25th percentile. Thus, a patient at the 75th percentile for kynurenine/tryptophan levels had 2.1 fewer days without acute brain dysfunction than a patient at the 25th percentile. This comparison between percentiles is more clinically relevant than the traditionally used one-unit change.

a

Patients in this cohort received sedation with either dexmedetomidine or lorazepam. Patients using dexmedetomidine (as compared to lorazepam) had 2.1 more days alive and free from delirium and coma.