. Author manuscript; available in PMC: 2020 May 1.

Published in final edited form as: Transfusion. 2019 Feb 23;59(5):1675–1682. doi: 10.1111/trf.15216

Table 4.

Multivariable Analysis of Risk Factors for BPD with Reliability ≥ 50% (n=592)

Risk Factor^a	Estimated β (SE)	Relative Risk of BPD (95% CI)	P	Reliability (%)^b
*Primary exposure*
Enteral iron (per 50 mg increase)^c	0.0010 (0.0004)	1.05 (1.01, 1.09)	0.01	69
*Secondary exposure*
RBC transfusion (per 20 ml increase)^c	0.0025 (0.0006)	1.05 (1.03, 1.08)	<0.001	100
*Other factors in multivariable model*
Gestational age (per 1 week increase)	−0.1853 (0.0288)	0.83 (0.79, 0.88)	<0.001	100
Surfactant on DOB (yes vs. no)	0.2396 (0.0951)	1.27 (1.05, 1.53)	0.01	54
Mechanical ventilation at 1 week of age (yes vs. no)	0.6262 (0.1551)	1.87 (1.38, 2.53)	<0.001	90

Abbreviations: BPD, bronchopulmonary dysplasia; SE, standard error; CI, confidence interval. RBC, red blood cell; DOB, day of birth.

Model fitted to outcome of BPD (n=240 events) and includes adjustment for center (not shown, P=0.0005). Four infants died before birth weight regained and 2 infants with missing weight gain data were excluded from the analysis.

Percentage of time risk factors appears in 1000 bootstrap models (factors ≥ 50% are reliable).

Cumulative exposure was evaluated from birth until postnatal age of BPD assessment.