Table 4.

Adjusted ORs for Study Outcomes Based on the Cumulative Duration of Mechanical Ventilation and the Number of Ventilation Courses

	Adjusted 0R^a (95% Cl)
Exposure	BPD	Discharged on Oxygen	Tracheostomy	Death
Duration of mechanical ventilation, d
≤7	1 [Reference]	1 [Reference]	1 [Reference]	1 [Reference]
8–21	2.73 (2.16–3.45)	1.35 (1.00–1.81)	0.97 (0.06–17.01)	0.60 (0.46–0.77)
22–35	4.62 (3.37–6.35)	2.13 (1.54–2.95)	3.02 (0.25–36.88)	0.33 (0.21–0.51)
≥36	8.69 (6.58–11.48)	3.28 (2.40–4.47)	6.30 (0.52–76.41)	0.11 (0.08–0.17)
No. of ventilation courses
1	1 [Reference]	1 [Reference]	1 [Reference]	1 [Reference]
2	1.88 (1.54–2.31)	1.41 (1.08–1.85)	2.73 (0.45–16.73)	0.75 (0.56–0.99)
3	2.56 (1.99–3.28)	1.62 (1.26–2.10)	1.10 (0.14–8.82)	0.68 (0.48–0.96)
≥4	3.81 (2.88–5.04)	1.58 (1.14–2.19)	2.27 (0.34–14.94)	0.66 (0.49–0.91)

Abbreviations: BPD, bronchopulmonary dysplasia; OR, odds ratio.

The ORs for death were determined for 3433 infants. The ORs for nondeath outcomes were determined for 2867 infants who survived to discharge. The ORs were adjusted for birth weight, gestational age, small for gestation age, sex, birth year, surfactant exposure, postnatal dexamethasone treatment, patent ductus arteriosus treatment, bacterial sepsis, and diagnosis of necrotizing enterocolitis.