Table 2 •.

Univariate and Multivariate Cox Regression Analysis According to CPX Time Period

	CPX: 1993-2005 (n = 381)		CPX: 2006-2010 (n = 511)
	Major Cardiac Events (n = 83)	Only Death (n = 74)	Major Cardiac Events (n = 162)	Only Death (n = 71)
Univariate analysisa
⩒E/⩒co2 slope	1.07 (1.06–1.09)c	1.07 (1.05–1.09c	1.06 (1.05–1.07)c	1.06 (1.05–1.08)c
Peak ⩒o2	0.90 (0.86–0.94)c	0.90 (0.86–0.94)c	0.82 (0.79–0.86)c	0.76 (0.71–0.82)c
Multivariate analysisb
⩒E/⩒co2 slope	80.7c	62.6c	114.7c	52.4c
Residual χ2
Peak ⩒o2	4.2d	4.3d	34.2c	27.4c

Abbreviations: CPX, cardiopulmonary exercise testing; ⩒E /⩒co₂, minute ventilation/carbon dioxide production; ⩒o₂, oxygen uptake.

^aReported as hazard ratio and 95% confidence interval.

^bReported as χ² and residual χ²

^cP < .001.

^dP < .05.