Table 6.

Cox proportional regression analysis evaluating ROX > 5.80 and ROX-HR > 6.80 for the likelihood of HFNC failure in patients initiated on HFNC for acute respiratory failure

		Univariate analysis	p value	Multivariate analysis	p value
ROX > 5.80	2 h	0.403 (0.213–0.763)	0.005	0.460 (0.238–0.892)	0.021
	6 h	0.365 (0.187–0.714)	0.003	0.494 (0.260–1.015)	0.055
	10 h	0.299 (0.142–0.626)	0.001	0.397 (0.176–0.894)	0.026
	18 h	0.300 (0.119–0.756)	0.011	0.138 (0.036–0.532)	0.004
	24 h	0.194 (0.067–0.563)	0.003	0.338 (0.101–1.136)	0.079
ROX-HR > 6.80	2 h	0.353 (0.178–0.702)	0.003	0.423 (0.211–0845)	0.015
	6 h	0.394 (0.201–0.772)	0.007	0.408 (0.201–0.828)	0.013
	10 h	0.301 (0.143–0.663)	0.002	0.369 (0.162–0.841)	0.018
	18 h	0.254 (0.105–0.616)	0.002	0.252 (0.098–0.645)	0.004
	24 h	0.177 (0.059–0.534)	0.002	0.234 (0.071–0.771)	0.017

Variables included in the multivariate analysis: gender, acute physiologic assessment and chronic health evaluation (APACHE) II, Charlson comorbidity index and number of chest x-ray quadrants involved.