Table 4b. Prognostic Utility of 6MWD vs. CPX Indices in Predicting All-Cause Mortality.

Model	Parameter	Chi Squire statistic	P value	Hazard Ratio* ( 95% confidence interval)	C-Index (95% confidence interval)	IDI
Unadjusted Univariate predictors	6MWD	94	<.0001	0.61 (0.55, 0.67)	0.65 (0.62, 0.68)
	Peak VO2	123	<.0001	0.48 (0.42, 0.55)	0.68 (0.65, 0.71)
	VE/Vco2 Slope	130	<.0001	1.58 (1.46, 1.71)	0.65 (0.61, 0.68)
Adjusted**	6MWD	55	<.0001	0.65 (0.57, 0.73)	0.72 (0.69, 0.75)	0.005
	Peak VO2	77	<.0001	0.51 (0.44, 0.59)	0.73 (0.71, 0.76)	0.010
	VE/VCO2 Slope	45	<.0001	1.37 (1.25, 1.51)	0.71 (0.68, 0.74)	0.004

6MWD-6 minute walk distance; VO₂-oxygen consumption; VE/VCO₂-minute ventilation-carbon dioxide production; IDI-Integrated Discrimination Improvement

^*Hazard Ratio based on Z score

^**--All-Cause Hospitalization/Mortality Model adjusted for Gender, Region (US vs. Non-US), Mitral Regurgitation, ECG Ventricular Conduction Abnormality, Blood Urea Nitrogen (BUN), Left Ventricular Ejection Fraction (LVEF), Carvedilol Equivalent Dose, and Kansas City Cardiomyopathy Questionnaire Symptom Stability Score --All-Cause Mortality Model adjusted for Gender, BMI, Loop Diuretic Dose, Angina Class, ECG Ventricular Conduction Abnormality, LVEF, and Creatinine

^***--6MWD (normalized) is truncated at 1 standard deviation in the model of Hospitalization/Mortality because of its lack of relationship with this endpoint beyond that point. Truncation in this case implies that the Hazard Ratio for values of 6MWD>1 is set to 1.

--Other truncated covariates are carvedilol equivalent dose-truncated above 50 mg/day; BMI-body mass index-truncated above 25 kg/m²; Cr-truncated above 2.3 mg/dl.

^****IDI Model includes N=2013 patients with non-missing values for 6MW, Peak VO₂, and VE/VCO₂