TABLE 1

Comparison of Original and Matched Samples

CharacteristicOriginal SampleMatched Sample
Discharged on Supplemental Oxygen (N = 1688)Discharged Breathing in Room Air (N = 1226)Standardized DifferenceDischarged on Supplemental Oxygen (N = 1039)Discharged Breathing in Room Air (N = 1039)Standardized Difference
Gestational age, mean ± SD24.7 ± 1.124.9 ± 1.00.1724.8 ± 1.024.8 ± 1.00.00
Birth wt, mean ± SD712.0 ± 149.0738.9 ± 144.10.18734.3 ± 147.0731.5 ± 145.20.02
Small for gestational age, n/N (%)152/1687 (9)60/1226 (5)0.1653/1039 (5)57/1039 (5)0.02
Male sex, n/N (%)911/1687 (54)629/1226 (51)0.05554/1039 (53)532/1039 (51)0.04
Private insurance, n/N (%)715/1679 (43)466/1214 (38)0.09418/1033 (40)396/1029 (38)0.04
Mother with less than high school education, n/N (%)275/1323 (21)225/928 (24)0.05187/804 (23)190/789 (24)0.02
White race, n/N (%)933/1660 (56)631/1197 (53)0.08576/1015 (57)539/1014 (53)0.07
Antenatal steroids, n/N (%)1516/1686 (90)1051/1220 (86)0.12912/1037 (88)895/1033 (87)0.04
Intubation, n/N (%)1482/1688 (88)1018/1226 (83)0.14889/1039 (86)881/1039 (85)0.02
Surfactant, n/N (%)1630/1688 (97)1138/1226 (93)0.17991/1039 (95)977/1039 (94)0.06
Surgery for necrotizing enterocolitis, n/N (%)54/1688 (3)81/1226 (7)0.1641/1039 (4)50/1039 (5)0.04
Severity of BPD, n/N (%)0.390.00
 Moderate BPD489/1688 (29)580/1226 (47)436/1039 (42)436/1039 (42)
 Severe BPD1199/1688 (71)646/1226 (53)603/1039 (58)603/1039 (58)
Postnatal steroids, n/N (%)604/1549 (39)245/1160 (21)0.39241/954 (25)226/987 (23)0.06
Prolonged positive pressure respiratory support, n/N (%)769/1686 (46)388/1225 (32)0.29341/1039 (33)341/1039 (33)0.00
Discharged on diuretics, n/N (%)655/1687 (39)219/1221 (18)0.47239/1039 (23)211/1035 (20)0.06
Discharged on bronchodilators, n/N (%)340/1686 (20)51/1221 (4)0.4860/1039 (6)50/1035 (5)0.04
  • All characteristics listed in the table were included in the propensity scores.