Table 3. Proportion of children in each group scoring < -2 SD on cognitive parameters of EF.
| Total population | NSI-free and FSIQ > 70 | |||||||
|---|---|---|---|---|---|---|---|---|
| EPT | Control | Adjusted ORa (95% CI) | P value | EPT | Control | Adjusted ORa (95% CI) | P value | |
| N = 128 | N = 103 | N = 98 | N = 99 | |||||
| Verbal conceptual reasoning (Sim) | 17 (13) | 0 | NA | < 0.001b | 2 (2) | 0 | NA | 0.24b |
| Verbal working memory (Ds) | 26 (20) | 2 (2) | 12.8 (3–56) | < 0.001 | 7 (7) | 2 (2) | 3.6 (.7–19) | 0.1 |
| Non-verbal memory, attention (Co) | 26 (20) | 3 (3) | 10.0 (2.9–35.0) | < 0.001 | 8 (8) | 2 (2) | 5.5 (1.1–27) | 0.039 |
| Memory, attention, distractibility (Ar) | 34 (27) | 4 (4) | 9.1 (3.1–6.2) | < 0.001 | 13 (13) | 2 (2) | 7.9 (1.7–37) | 0.008 |
| Spatial conceptualization (Bd) | 34 (27) | 2 (2) | 18.0 (4–77) | < 0.001 | 14 (14) | 0 | NA | < 0.001b |
| Visual reasoning (Pa) | 25 (20) | 5 (5) | 4.7 (1.8–12.7) | 0.003 | 8 (8) | 4 (4) | 2.1 (.6–7.3) | 0.24 |
| Planning ability (Tower test) | 26 (20) | 1 (1) | 26.0 (3.4–192) | < 0.002 | 7 (7) | 0 | NA | 0.007b |
EPT, extremely preterm (23–25 weeks); NSI, neurosensory impairment; FSIQ, full-scale intelligence quotient; Sim, similarities; Ds, digit span; Bd, block design; Pa, picture arrangement; Co, coding; Ar, arithmetic; OR, odds ratio; CI, confidence interval; NA, not appropriate for calculation due to wide confidence intervals for exponents.
The values are n (%) unless otherwise stated. The data were adapted from core subtests of the WISC-III-R (Swedish edition, Wechsler 1999) [31] and the Tower test of the Delis-Kaplan Executive Function Scale [30].
a The ORs were derived from logistic regression analyses adjusted for the children’s gender and social risk (any vs none, see ‘Methods‘) and mother’s country of birth (Nordic vs non-Nordic).
b P values were determined by Fisher’s exact test for the EPT children vs control subjects.