Table 1. Relationships between IDO markers as well as other variables and new bacterial infection as determined by multivariate Cox regression analysis.

Model 1 including IDO MFI
Variables	Hazard ratio (95% CI)	P
IDO MFI (Quartile 4 vs. Quartile 1)	9.257 (2.723-31.475)	<0.001
Age (for every 10-year increase)	1.017 (0.807-1.281)	0.888
GNRI (for every 10-point increase)	1.284 (0.773-2.132)	0.335
Months on dialysis (for every 1-month increase)	1.001 (1.000-1.002)	0.045
Model 2 including the Kyn/Trp ratio
Variables	Hazard ratio (95% CI)	P
Kyn/Trp ratio (Quartile 4 vs. Quartile 1)	0.634 (0.228-1.761)	0.382
Age (for every 10-year increase)	1.075 (0.842-1.371)	0.563
GNRI (for every 10-point increase)	1.056 (0.637-1.749)	0.834
Months on dialysis (for every 1-month increase)	1.001 (1.000-1.002)	0.059

Multivariate Cox regression analysis was performed by adjusting for 4 different variables. Models 1 and 2 were applied to investigate the quartiles of the two IDO markers, the IDO MFI and the Kyn/Trp ratio. In Model 1, high IDO MFI quartile (Quartile 4 vs. Quartile 1) was correlated with new bacterial infection, whereas in Model 2, high Kyn/Trp ratio quartile was not correlated with new bacterial infection. IDO: indoleamine 2,3-dioxygenase; MFI: median fluorescence index; GNRI: Geriatric Nutritional Risk Index.