Table 1. Characteristics of Eligible and Matched Infants by Corticosteroid Treatment Statusa.
| Characteristic | Eligible sample | Matched sample | ||||
|---|---|---|---|---|---|---|
| Corticosteroid-treated infants, No./total No. (%) | Untreated controls, No./total No. (%) | Standardized difference | Corticosteroid- treated infants, No./total No. (%) | Untreated controls, No./total No. (%) | Standardized difference | |
| Maternal | ||||||
| Antenatal corticosteroids | 597/656 (91.0) | 2507/2796 (89.7) | 0.05 | 435/482 (90.2) | 427/482 (88.6) | 0.05 |
| Antenatal antibiotics | 497/656 (75.8) | 2095/2796 (74.9) | 0.02 | 357/482 (74.1) | 345/482 (71.6) | 0.06 |
| Multiple birth | 179/656 (27.3) | 695/2796 (24.9) | 0.06 | 127/482 (26.3) | 127/482 (26.3) | 0.00 |
| Race and ethnicityb | ||||||
| Black race | 277/636 (43.6) | 1243/2719 (45.7) | 0.04 | 198/469 (42.2) | 201/473 (42.5) | 0.01 |
| White race | 327/636 (54.4) | 1320/2719 (48.5) | 0.04 | 242/469 (51.6) | 247/473 (52.2) | 0.01 |
| Other race | 32/636 (5.0) | 156/2719 (5.7) | 0.04 | 29/469 (6.2) | 25/473 (5.3) | 0.01 |
| Hispanic or Latino ethnicity | 67/650 (10.3) | 419/2765 (15.2) | 0.15 | 53/478 (11.1) | 54/479 (11.3) | 0.01 |
| Non-Hispanic or non-Latino ethnicity | 583/650 (89.7) | 2346/2719 (86.3) | 0.15 | 425/478 (88.9) | 425/479 (88.7) | 0.01 |
| Greater than high school educational level | 283/520 (54.4) | 1131/2261 (50.0) | 0.09 | 207/384 (53.9) | 223/382 (58.4) | 0.09 |
| Demographic and perinatal | ||||||
| Gestational age, mean (SD), wk | 24.3 (1.1) | 24.9 (1.1) | 0.57 | 24.4 (1.1) | 24.4 (1.1) | 0.00 |
| Birth weight, mean (SD), g | 673 (135) | 763 (166) | 0.59 | 682 (135) | 672 (146) | 0.08 |
| Female sex | 282/656 (43.0) | 1434/2796 (51.3) | 0.17 | 212/482 (44.0) | 212/482 (44.0) | 0.00 |
| Male sex | 374/656 (57.0) | 1362/2796 (48.7) | 0.17 | 270/482 (56.0) | 270/482 (56.0) | 0.00 |
| Endotracheal tube placed in the delivery room | 573/656 (87.3) | 2133/2796 (76.3) | 0.29 | 415/482 (86.1) | 426/482 (88.4) | 0.07 |
| Received surfactant | 634/656 (96.6) | 2471/2796 (88.4) | 0.32 | 463/482 (96.1) | 469/482 (97.3) | 0.07 |
| Received indomethacin in the first 24 h | 243/656 (37.0) | 1179/2796 (42.2) | 0.10 | 182/482 (37.8) | 187/482 (38.8) | 0.02 |
| Treated for hypotension in the first 24 h | 241/656 (36.7) | 825/2796 (29.5) | 0.15 | 191/482 (39.6) | 180/482 (37.3) | 0.05 |
| Postnatalc | ||||||
| Grade 3 or 4 IVH | NA | NA | NA | 68/482 (14.1) | 69/428 (14.3) | 0.01 |
| Culture-confirmed sepsis or meningitis | NA | NA | NA | 102/482 (21.2) | 92/482 (19.1) | 0.05 |
| Surgery for necrotizing enterocolitis or intestinal perforation | NA | NA | NA | 35/482 (7.3) | 41/482 (8.5) | 0.05 |
| Days on positive airway pressure | NA | NA | NA | 20.4 (7.7) | 20.4 (7.6) | 0.002 |
| Days on invasive ventilation | NA | NA | NA | 18.6 (7.8) | 18.5 (8.0) | 0.01 |
| Last recorded mode of support | 0.00 | |||||
| HFV | NA | NA | NA | 213/482 (44.2) | 213/482 (44.2) | |
| Conventional ventilation | NA | NA | NA | 240/482 (49.8) | 240/482 (49.8) | |
| NIMV, nCPAP, or NC | NA | NA | NA | 29/482 (6.0) | 29/482 (6.0) | |
| Last recorded Fio2, mean (SD) | NA | NA | NA | 0.57 (0.24) | 0.56 (0.24) | 0.02 |
| Pretreatment probability of death or grade 2 or 3 BPD at 36 weeks’ PMA, mean (SD) | NA | NA | NA | 0.53 (0.22) | 0.53 (0.22) | 0.01 |
Abbreviations: BPD, bronchopulmonary dysplasia; Fio2, fraction of inspired oxygen; HFV, high-frequency ventilation; IVH, intraventricular hemorrhage; NA, not applicable; NC, nasal cannula; nCPAP, nasal continuous positive airway pressure; NIMV, noninvasive mechanical ventilation; PMA, postmenstrual age.
Data are expressed as the number (%) of infants unless otherwise indicated. Data are shown for the infants with known values for the specified covariates. A full list of all variables used to estimate the propensity score values is provided in the eAppendix in Supplement 1. Comparisons of all propensity score variables between corticosteroid-treated and untreated controls who were eligible or included in the matched cohort are provided in eTables 4 and 5 in Supplement 1. The distribution of propensity score values in the matched cohort is shown in eFigure 1 in Supplement 1.
Race and ethnicity were self-identified in the Generic Database and selected from the following options: Black, Hispanic or Latino, or White. The “other” catgory included American Indian or Alaska Native, Asian, Native Hawaiian or other Pacific Islander, more than 1 race, unknown, or not reported.
Values indicate postnatal exposures recorded prior to corticosteroid initiation or the same PMA week in the matched controls. Similar values could not be computed for the eligible untreated controls prior to matching on a specific PMA.