Table 2. Primary Outcome in All Patients and by Patient Subgroups.

	Median (IQR), d		Estimate of difference (95% CI)	Unadjusted HR (95% CI)	Adjusted HR (95% CI)	P value
	High-flow oxygen	Standard oxygen
Primary outcome: length of hospital stay
All patients for time since randomization	(n = 753) 1.77 (1.03 to 2.80)	(n = 764) 1.50 (0.85 to 2.44)	0.27 (0.13 to 0.41)	0.85 (0.77 to 0.94)	0.83 (0.75 to 0.92)	<.001a
By wheeze
Present (n = 1066)b	1.62 (0.92 to 2.58)	1.43 (0.82 to 2.12)	0.19 (0.03 to 0.34)	0.86 (0.77 to 0.97)	0.85 (0.75 to 0.96)	.71c
Absent (n = 451)	2.20 (1.31 to 3.47)	1.86 (0.93 to 2.97)	0.340 (−0.003 to 0.690)	0.82 (0.68 to 0.98)	0.81 (0.67 to 0.98)
By obstructive diseased
Present (n = 958)b	1.53 (0.90 to 2.34)	1.28 (0.77 to 2.02)	0.24 (0.08 to 0.40)	0.90 (0.80 to 1.03)	0.87 (0.76 to 0.99)	.38c
Absent (n = 559)	2.31 (1.29 to 3.79)	1.93 (1.28 to 2.95)	0.37 (0.03 to 0.70)	0.82 (0.70 to 0.97)	0.81 (0.68 to 0.96)
By age at randomization, median (IQR)e
1 y (n = 777)b	1.87 (1.12 to 2.80)	1.53 (0.95 to 2.61)	0.33 (0.14 to 0.53)	0.90 (0.78 to 1.04)	0.84 (0.72 to 0.97)	.08f
2 y (n = 372)	1.62 (0.82 to 2.82)	1.45 (0.73 to 2.30)	0.17 (−0.15 to 0.48)	0.90 (0.74 to 1.11)	0.90 (0.73 to 1.11)
3 y (n = 189)	1.74 (1.21 to 2.77)	1.60 (0.77 to 2.30)	0.15 (−0.26 to 0.56)	0.79 (0.60 to 1.06)	0.84 (0.62 to 1.14)
4 y (n = 149)	1.47 (1.11 to 2.47)	1.49 (0.68 to 2.25)	−0.009 (−0.490 to 0.470)	0.56 (0.40 to 0.79)	0.60 (0.42 to 0.85)

Abbreviation: HR, hazard ratio.

^a Adjusted for presence or absence of obstructive airway disease at randomization and study site.

^b Sample sizes larger than original group sizes because patients could switch treatment and receive high-flow oxygen or standard oxygen.

^c Associated with an interaction term and derived from an adjusted model.

^d Defined as a discharge diagnosis of reactive airway disease, asthma, or bronchiolitis.

^e Restricted to children aged 1 to 4 years (n = 1487).

^f Derived from the Wald test and an adjusted model.