Table 1.
Demographic information
| ASD | NDD | ||||
|---|---|---|---|---|---|
| NVIQ> 70 | NVIQ<= 70 | NVIQ> 70 | NVIQ<= 70 | ||
| n | 148 | 64 | 308 | 46 | |
| Age at assessment (months), M ± SD | 71.31 ± 28.15 | 57.08 ± 23.06 | 45.89 ± 14.45 | 45.18 ± 11.96 | |
| Sex (female), n (%) | 22 (14.86) | 17 (26.56) | 82 (26.62) | 12 (26.09) | |
| Walking at time of assessment, n (%) | 148 (100%) | 59 (92.19%) | 307 (99.68%) | 36 (78.26%) | |
| Age of walking*, median (IQR) | 14 (12-16) | 15 (12-18) | 14 (12-16) | 23 (18.50-27.50) | |
| Walking at or after 18 months**], n (%) | 22 (14.86%) | 21 (32.81%) | 41 (13.31%) | 39 (84.78%) | |
| Nonverbal IQ, M ± SD | 99.09 ± 17.05 | 49.48 ± 15.76 | 97.87 ± 12.82 | 48.19 ± 17.23 | |
| Birth weight (grams), M ± SD | 3595.12 ± 734.51 | 3470.17 ± 706.03 | 3460.45 ± 694.95 | 3139.85 ± 613.63 | |
| Low birth weight (<2500g), n (%) | 10 (6.76) | 5 (7.81) | 25 (8.12) | 4 (8.70) | |
| Gestational Age (weeks), n (%) | 22-27 | 1 (0.68) | 1 (1.56) | 1 (0.32) | - |
| 28-36 | 12 (8.11) | 4 (6.25) | 31 (10.06) | 8 (17.39) | |
| 37 | 9 (6.08) | 4 (6.25) | 23 (7.47) | 4 (8.70) | |
| 38 | 19 (12.84) | 9 (14.06) | 42 (13.64) | 9 (19.57) | |
| 39 | 30 (20.27) | 11 (17.19) | 63 (20.45) | 6 (13.04) | |
| 40 | 38 (25.68) | 14 (21.88) | 81 (26.30) | 7 (15.22) | |
| 41 | 24 (16.22) | 16 (25) | 46 (14.94) | 9 (19.57) | |
| 42 | 14 (9.46) | 5 (7.81) | 21 (6.82) | 3 (6.52) | |
| Missing | 1 (0.68) | - | - | - | |
| APGAR 1 minute, Median (IQR) | 9 (8-9) | 9 (8-9) | 9 (9-9) | 9 (8-9) | |
| Low APGAR 1, n (%) | 10 (6.76) | 5 (7.81) | 27 (8.77) | 5 (10.87) | |
| APGAR 5 minutes, Median (IQR) | 9 (9-10) | 9 (9-10) | 9 (9-10) | 9 (9-10) | |
| Low APGAR 5, n (%) | 3 (2.03) | 2 (3.13) | 8 (2.60) | 1 (2.17) | |
| Genetic Syndrome, n (%) | 4 (2.70) | 7 (10.94) | 6 (1.95) | 11 (23.91) | |
| First words by 18 months, n (%) | Yes | 51 (34.46) | 10 (15.63) | 69 (22.40) | 3 (6.52) |
| No | 63 (42.57) | 37 (57.81) | 198 (64.29) | 38 (82.61) | |
| Missing | 34 (22.97) | 17 (26.56) | 41 (13.31) | 5 (10.87) | |
| First phrases by 36 months, n (%) | Yes | 103 (69.59) | 20 (31.25) | 241 (78.25) | 11 (23.91) |
| No | 18 (12.16) | 33 (51.56) | 51 (16.56) | 34 (73.91) | |
| Missing | 27 (18.24) | 11 (17.19) | 16 (5.19) | 1 (2.17) | |
Notes: IQR=interquartile range. Nonverbal IQ was categorized for the purpose of this table only and was entered as a continuous variable in all analyses.
*
Children who were not yet walking at the time of assessment (age range 37-46 months) had missing data on age of walking (ASD n=5 (2%), other NDDs n=11 (3%)).
**
The 97th percentile in the Norwegian data (18 months) was used as a classifier for late walking in this table only (continuous age of walking was used for all analyses).