Table 1.
Baseline characteristics of the Chinese infants by completeness of data on cotinine and SDQ.
| Subjects with complete data for cotinine and SDQ (n = 189) | Subjects without complete data for cotinine and SDQ (n = 503) | P valuea | Effect size | |||
|---|---|---|---|---|---|---|
| N | (%) | N | (%) | |||
| Mean (SD) log10-cotinine level, ng/ml | 0.049 | (0.38) | 0.062 | (0.39) | 0.72 | 0.036 |
| Mean (SD) age, month | 6.2 | (5.0) | 6.7 | (6.0) | 0.68 | 0.085 |
| Mean (SD) birthweight, kg | 3.17 | (0.46) | 3.14 | (0.59) | 0.59 | 0.046 |
| Sex | 0.89 | 0.005 | ||||
| Boys | 97 | (51.3) | 261 | (51.9) | ||
| Girls | 92 | (48.7) | 242 | (48.1) | ||
| Monthly household income (HK$)b | 0.24 | 0.078 | ||||
| ≤$9999 | 14 | (7.4) | 57 | (11.4) | ||
| $10000–19999 | 54 | (28.6) | 159 | (31.8) | ||
| $20000–29999 | 45 | (23.8) | 115 | (23.0) | ||
| ≥$30000 | 76 | (40.2) | 169 | (33.8) | ||
| Housing type | 0.12 | 0.093 | ||||
| Private housing | 80 | (42.3) | 200 | (39.9) | ||
| Subsidized sale flats | 42 | (22.2) | 80 | (16.0) | ||
| Public rental housing | 62 | (32.8) | 200 | (39.9) | ||
| Others | 5 | (2.7) | 21 | (4.2) | ||
| Maternal education | 0.50 | 0.045 | ||||
| Junior secondary or below | 33 | (17.5) | 100 | (20.0) | ||
| Senior secondary | 90 | (47.6) | 248 | (49.5) | ||
| Tertiary | 66 | (34.9) | 153 | (30.5) | ||
aComputed by t test, Mann-Whitney U test and Pearson χ2 test as appropriate. bHK$7.8 ≈ US$1.