Table 1– Demographic and diagnostic information of respiratory syncytial virus (RSV)-induced respiratory failure subjects and controls

	Nonlung disease controls^#	Non-RSV pneumonia controls	RSV-induced respiratory failure^¶	p-value
Subjects	46	29	42
Age months	21.6±4.6 (4 weeks–11 years)	10.45±2.9 (3 weeks–7 years)	2.8±0.5 (1 week–5 months)	<0.001
Sex				0.26
Female	14	14	18
Male	32	15	24
Length of intubation days	4.9±0.4	9.2±1.5	5.3±0.6	0.006
Length of PICU stay days	6.1±0.4	10.03±1.5	7.36±0.9	0.049
PRISM-12	4.78±0.8	8.8±1.4	5.7±0.7	0.003
PRISM-24	4.47±0.6	6.8±0.8	3.3±0.6	0.004
F_IO₂	0.37±0.007	0.63±0.02	0.48±0.02	<0.001
Diagnosis	Closed head injury 15	Bacterial pneumonia^§ 16	RSV bronchiolitis 32
	Seizure 9	Viral pneumonia^ƒ 9	RSV pneumonia 10
	Post-laryngotracheal reconstruction 8	Fungal pneumonia^## 2
	Altered mental status 4	Aspiration pneumonia 2
	Muscular weakness 2
	Other⁺ 8

Data are presented as n, mean±sem (range) or mean±sem, unless otherwise stated. All control subjects who developed new radiographic changes while on the ventilator or acquired a new viral or bacterial infection were excluded from the study. PICU: paediatric intensive care unit; PRISM-12: paediatric risk of mortality in 12 h; PRISM-24: paediatric risk of mortality in 24 h; F_IO₂: inspiratory oxygen fraction. ^#: Nonlung disease controls had no evidence of acute or chronic lung disease, with minimal ventilator requirements (low F_IO₂, positive end-expiratory pressure, tidal volume and ventilatory rate) and clear chest radiographs; ^¶: having a positive RSV culture on admission to the hospital; ⁺: includes subjects with arrhythmia, posterior spinal fusion, cervical spine injuries and nasopharyngeal mass. ^§: pneumonia secondary to Staphylococcus aureus (n=9), Pseudomonas aeruginosa (n=3), Streptococcus pneumoniae (n=3) and Serratia marcescens (n=1); ^ƒ: pneumonia secondary to influenza (n=5), adenovirus (n=3) and parvovirus (n=1); ^##: pneumonia secondary to Candida albicans (n=2).