Table 3.

Variables associated with Length of Stay

Variable	Univariable analysis		Multivariable analysis
	r	p	b	95%CI	p
dNIV-72 h	0.510	p < 0.001	0.13	0.04–0.21	0.003
dNIV-48 h	0.381	p < 0.001
Days of NIV	0.542	p < 0.001	0.68	0.31–1.05	< 0.001

Legend:

dNIV-48 h / -72 h = duration of NIV in hours in the first 24 h, 48 h and respectively 72 h

Days of NIV = number of days with non-invasive ventilation

r correlation coefficient; b regression coefficient; 95%CI 95% confidence interval