TABLE 4.
Characteristics of the 4 Clusters for Longitudinal Changes in WISC-III Vocabulary Raw Scores
| Cluster A | Cluster B | Cluster C | Cluster D | |
|---|---|---|---|---|
| n | 51 | 65 | 116 | 77 |
| Proportion of total preterm cohort, %, n = 309 | 17 | 21 | 38 | 25 |
| Child characteristics | ||||
| Gestational age, mean (SD), wk | 27.9 (1.9) | 28.0 (1.9) | 28.0 (1.9) | 27.9 (2.0) |
| Birth weight, mean (SD), g | 950 (173) | 969 (172) | 968 (157) | 905 (192) |
| Male gender, n (%) | 27 (53) | 38 (58) | 62 (53) | 41 (53) |
| Multiple, n (%) | 9 (18) | 12 (18) | 31 (27) | 16 (21) |
| Small for gestational age, n (%) | 11 (22) | 17 (26) | 29 (25) | 17 (22) |
| Maternal steroids, n (%) | 21 (41) | 23 (35) | 43 (37) | 23 (30) |
| Indomethacin, n (%) | 25 (49) | 31 (48) | 59 (52) | 39 (53) |
| Bronchopulmonary dysplasia, n (%) | 19 (38) | 32 (49) | 50 (43) | 39 (51) |
| Neonatal brain injury, n (%) | ||||
| None | 41 (80) | 48 (74) | 93 (80) | 49 (64) |
| Severe brain injurya | 6 (12) | 4 (6) | 3 (3) | 14 (18) |
| NSI, n (%)b | 6 (12) | 8 (12) | 7 (6) | 22 (29) |
| Family factors | ||||
| Maternal age at birth, mean (SD), y | 30.0 (6.0) | 27.2 (5.6) | 27.9 (5.9) | 27.0 (6.0) |
| Maternal education, n (%) | ||||
| High school or less | 7 (14) | 28 (43) | 39 (34) | 48 (62) |
| ≥1 year of college | 44 (86) | 37 (57) | 76 (66) | 29 (38) |
| Race and ethnicity, n (%) | ||||
| Non-Hispanic white | 44 (86) | 44 (68) | 78 (67) | 45 (59) |
| Others | 7 (14) | 21 (32) | 38 (33) | 31 (41) |
| Bilingual environment, n (%) | 6 (12) | 8 (12) | 12 (10) | 15 (20) |
| Single-parent household at the age of 16 y, n (%) | 12 (24) | 22 (34) | 32 (28) | 35 (45) |
a
Severe brain injury includes grades 3 to 4 intraventricular hemorrhage, periventricular leukomalacia, and grade 2 and above ventriculomegaly.
b
NSI includes the presence of any of the following: abnormal neurological examination including cerebral palsy, ventriculo peritoneal shunt, seizure disorder, hearing aids, services for the blind.