Table 1.
Baseline characteristics of the pediatric population before and after inverse probability of treatment weighting (IPTW)
| Pre-IPTW | Post-IPTW | |||||||
|---|---|---|---|---|---|---|---|---|
| EP group n = 3518 (0.2) |
OP group n = 82,579 (3.7) |
FT group n = 2,138,379 (96.1) |
Maximum ASD | EP group n = 3549 (0.2) |
OP group n = 82,938 (3.7) |
FT group n = 2,138,358 (96.1) |
Maximum ASD |
|
| Variables included in IPTW | ||||||||
| Sex | 0.07 | 0.03 | ||||||
| Boys | 1796 (51.0) | 45,097 (54.6) | 1,093,814 (51.1) | 1877 (52.9) | 43,303 (52.2) | 1,096,585 (51.2) | ||
| Girls | 1722 (49.0) | 37,482 (45.4) | 1,044,565 (48.9) | 1672 (47.1) | 39,635 (47.8) | 1,041,773 (48.7) | ||
| Birth year | 0.08 | 0.05 | ||||||
| 2008–2010 | 1235 (35.1) | 32,362 (39.2) | 821,608 (38.4) | 1337 (37.7) | 29,248 (35.3) | 821,966 (38.4) | ||
| 2011–2014 | 2283 (64.9) | 50,217 (60.8) | 1,316,771 (61.6) | 2212 (62.3) | 53,690 (64.7) | 1,316,393 (61.6) | ||
| Residence | 0.03 | 0.03 | ||||||
| Metropolitan | 1608 (45.7) | 37,968 (46.0) | 952,951 (44.6) | 1563 (44.0) | 37,532 (45.3) | 954,128 (44.6) | ||
| Rural | 1910 (54.3) | 44,611 (54.0) | 1,185,428 (55.4) | 1986 (56.0) | 45,406 (54.7) | 1,184,230 (55.4) | ||
| SES | 0.05 | 0.07 | ||||||
| Q1 | 410 (11.7) | 9368 (11.3) | 226,689 (10.6) | 366 (10.3) | 8809 (10.6) | 227,311 (10.6) | ||
| Q2 | 795 (22.6) | 18,420 (22.3) | 495,053 (23.2) | 822 (23.2) | 19,200 (23.2) | 494,359 (23.1) | ||
| Q3 | 1429 (40.6) | 32,164 (39.0) | 856,067 (40.0) | 1470 (41.4) | 33,207 (40.0) | 855,219 (40.0) | ||
| Q4 | 884 (25.1) | 22,627 (27.4) | 560,570 (26.2) | 891 (25.1) | 21,722 (23.2) | 561,469 (26.3) | ||
| Maternal asthma | 181 (5.1) | 4172 (5.1) | 94,938 (4.4) | 0.03 | 173 (4.9) | 3733 (4.5) | 95,450 (4.5) | 0.02 |
| Maternal AD | 82 (2.3) | 1843 (2.2) | 44,967 (2.1) | 0.01 | 72 (2.0) | 1758 (2.1) | 45,077 (2.1) | < 0.01 |
| Variables not included in IPTW | ||||||||
| GDM | 371 (10.6) | 21,187 (25.7) | 476,637 (22.3) | 0.40 | 848 (23.9) | 19,315 (23.3) | 478,865 (22.4) | 0.04 |
| Cesarean section | 2136 (60.7) | 45,903 (55.6) | 731,008 (24.2) | 0.79 | 1221 (34.4) | 28,649 (34.5) | 748,858 (35.0) | 0.23 |
| PIH | 120 (3.4) | 4904 (5.9) | 61,824 (2.9) | 0.15 | 110 (3.1) | 2375 (2.9) | 64,242 (3.0) | 0.01 |
| IUGR | 105 (3.0) | 2899 (3.5) | 6000 (0.3) | 0.23 | 95 (2.7) | 2621 (3.2) | 6008 (0.3) | 0.22 |
| RDS | 3017 (85.8) | 18,020 (21.8) | 11,485 (0.5) | 3.39 | 2951 (83.2) | 16,838 (20.3) | 11,519 (0.5) | 3.07 |
| BPD | 2620 (74.5) | 4964 (6.0) | 202 (< 0.1) | 2.41 | 2511 (70.8) | 4612 (5.6) | 204 (< 0.1) | 2.20 |
| Pulmonary hypertension | 258 (7.3) | 745 (0.9) | 708 (< 0.1) | 0.39 | 241 (6.8) | 708 (0.9) | 715 (< 0.1) | 0.38 |
| Allergic proctocolitis | 56 (1.6) | 1044 (1.3) | 25,830 (1.2) | 0.03 | 74 (2.1) | 1003 (1.2) | 25,855 (1.2) | 0.07 |
| Birth weight, kg | 1.1 (0.9, 2.0) | 2.3 (1.9, 2.6) | 3.2 (3.0, 3.5) | 8.23 | 1.1 (0.9, 2.1) | 2.3 (1.9, 2.6) | 3.2 (3.0, 3.5) | 8.10 |
Categorical variables are presented as number (%). Abbreviations: IPTW, inverse probability of treatment weighting; EP, extremely preterm; OP, other preterm; FT, full term; SES, socioeconomic status; Q, quartile; AD, atopic dermatitis; ASD, absolute standardized difference; GDM, gestational diabetes mellitus; PIH, pregnancy-induced hypertension; IUGR, intrauterine growth restriction; RDS, respiratory distress syndrome; BPD, bronchopulmonary dysplasia. Categorical variables are presented as number (%) and continuous variables are presented as median (Q1, Q3)