Table 5.

Adjusted ORs for Adverse Respiratory Outcomes Among Survivors Obtained From the Logistic Regression Model Inclusive of the Duration of Mechanical Ventilation and the Number of Ventilation Courses

	Adjusted 0R^a (95% Cl)
Exposure	BPD	Discharged on Oxygen	Tracheostomy
Duration of mechanical ventilation, d
≤7	1 [Reference]	1 [Reference]	1 [Reference]
8–21	2.44 (1.90–3.13)	1.32 (0.96–1.83)	0.86 (0.04–20.74)
22–35	4.04 (2.90–5.64)	2.14 (1.46–3.13)	2.91 (0.17–48.89)
≥36	7.10 (5.18–9.74)	3.50 (2.30–5.31)	7.80 (0.41–147.23)
No. of ventilation courses
1	1 [Reference]	1 [Reference]	1 [Reference]
2	1.22 (0.97–1.53)	1.10 (0.83–1.50)	2.13 (0.28–16.04)
3	1.23 (0.92–1.63)	1.03 (0.76–1.41)	0.57 (0.05–6.00)
≥4	1.44 (1.04–2.01)	0.85 (0.56–1.31)	0.96 (0.12–7.67)
Interaction term P value^b	.15	.14	.07^c

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

The ORs 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, diagnosis of necrotizing enterocolitis, cumulative duration of mechanical ventilation, and number of ventilation courses.

P values for the interaction terms provided for reference only. Interaction terms not included in the regression models secondary to P > .05.

The multivariable tracheostomy model did not converge when categorical definitions for the duration of mechanical ventilation and the number of ventilation courses were used. When the duration of mechanical ventilation was used as a continuous variable, the interaction P value was .07.