Risk factor | Children (N) | Child-months (N) | Symptomatic new VDE OR (95% CI); P value | Asymptomatic new VDE OR (95% CI); P value | ||||
n | Unadjusted | Adjusted* | n | Unadjusted | Adjusted | |||
Age (months) | ||||||||
0–<3 | 151 | 423.3 | 60 | Referent rate | Referent rate | 58 | Referent rate | Referent rate |
3–<6 | 142 | 398.0 | 92 | 1.6 (1.2 to2.3); 0.003 | 1.7 (1.2 to 2.4); 0.003 | 90 | 1.7 (1.2, to 2.3); 0.003 | 1.5 (1.0 to 2.2); 0.03 |
6–<12 | 135 | 715.4 | 354 | 3.5 (2.6 to 4.6); <0.001 | 3.6 (2.4 to 5.4); <0.001 | 146 | 1.5 (1.1 to 2.0); 0.01 | 1.2 (0.8 to 1.8); 0.46 |
12–<24 | 117 | 1250.6 | 627 | 3.5 (2.7 to 4.6); <0.001 | 3.1 (2.0 to 4.7); <0.001 | 270 | 1.6 (1.2 to 2.1); 0.001 | 1.2 (0.7 to 1.8); 0.54 |
Sex | ||||||||
Male | 74 | 1255.1 | 481 | Referent rate | Referent rate | 262 | Referent rate | Referent rate |
Female | 77 | 1532.2 | 652 | 1.1 (1.0 to 1.4), 0.17 | 1.1 (0.9 to 1.3); 0.33 | 302 | 1.0 (0.8 to 1.2); 0.79 | 0.9 (0.7 to 1.2); 0.53 |
Type of delivery | ||||||||
Vaginal | 103 | 1876.3 | 802 | Referent rate | Referent rate | 387 | Referent rate | Referent rate |
Caesarean | 48 | 910.9 | 331 | 0.8 (0.7 to 1.0); 0.12 | 0.8 (0.7 to 1.0); 0.09 | 177 | 0.9 (0.7 to 1.2); 0.64 | 1.0 (0.8 to 1.3); 0.94 |
Gestational age at birth | ||||||||
Term (39w0d–41w6d) | 117 | 2219.1 | 937 | Referent rate | Referent rate | 446 | Referent rate | Referent rate |
Late preterm/early term (36w0d–38w6d) | 34 | 568.1 | 196 | 0.8 (0.7 to 1.1); 0.17 | 0.9 (0.7 to 1.2); 0.48 | 118 | 1.1 (0.8 to 1.5); 0.58 | 1.1 (0.8 to 1.5); 0.40 |
Season | ||||||||
Summer | 140 | 678.8 | 196 | Referent rate | Referent rate | 138 | Referent rate | Referent rate |
Autumn | 138 | 702.0 | 290 | 1.4 (1.2 to 1.7); <0.001 | 1.4 (1.2 to 1.7); <0.001 | 135 | 0.9 (0.7 to 1.2); 0.64 | 1.0 (0.8 to 1.2); 0.75 |
Winter | 138 | 706.6 | 350 | 1.7 (1.4 to 2.1); <0.001 | 1.6 (1.3 to 1.9); <0.001 | 142 | 1.0 (0.8 to 1.3); 0.93 | 0.9 (0.7 to 1.2); 0.67 |
Spring | 142 | 699.9 | 297 | 1.5 (1.2 to 1.8); <0.001 | 1.4 (1.2 to 1.7); <0.001 | 149 | 1.1 (0.8 to 1.3); 0.68 | 1.1 (0.8 to 1.4); 0.56 |
Family history | ||||||||
None present for asthma/eczema | 73 | 1289.6 | 533 | Referent rate | Referent rate | 286 | Referent rate | Referent rate |
Either parent asthma/eczema | 75 | 1447.3 | 582 | 1.0 (0.8 to 1.2); 0.93 | 1.0 (0.8 to 1.2); 0.85 | 264 | 0.8 (0.7 to 1.1); 0.16 | 0.9 (0.7 to 1.1); 0.22 |
First-degree relative asthma/eczema† | 78 | 1497.7 | 600 | 1.0 (0.8 to 1.2); 0.80 | 1.0 (0.8 to 1.2); 0.71 | 278 | 0.9 (0.7 to 1.1); 0.22 | 0.9 (0.7 to 1.1); 0.36 |
Tobacco smoke exposure | ||||||||
No exposure | 129 | 2383.4 | 973 | Referent rate | Referent rate | 472 | Referent rate | Referent rate |
Either parent smokes | 17 | 307.4 | 127 | 1.0 (0.7 to 1.4); 0.86 | 0.9 (0.6 to 1.1); 0.29 | 75 | 1.2 (0.8 to 1.7); 0.42 | 1.1 (0.8 to 1.7); 0.51 |
Household size | ||||||||
No other children in household | 99 | 1864.9 | 723 | Referent rate | Referent rate | 350 | Referent rate | Referent rate |
More than one child in household | 52 | 922.4 | 410 | 1.1 (0.9 to 1.4); 0.28 | 1.1 (0.9 to 1.4); 0.17 | 214 | 1.3 (1.0 to 1.7); 0.05 | 1.4 (1.0 to 1.7); 0.04 |
Maternal education status | ||||||||
High school | 14 | 246.7 | 113 | 1.1 (0.8 to 1.6); 0.56 | 1.0 (0.8 to 1.4); 0.81 | 62 | 1.4 (0.9 to 2.1); 0.11 | 1.4 (0.9 to 2.1); 0.17 |
Diploma/certificate | 36 | 650.2 | 245 | 0.9 (0.7 to 1.1); 0.37 | 0.9 (0.7 to 1.1); 0.25 | 149 | 1.2 (0.9 to 1.6); 0.29 | 1.2 (0.9 to 1.6); 0.15 |
University/higher university degree | 95 | 1828.3 | 750 | Referent rate | Referent rate | 346 | Referent rate | Referent rate |
Mode of feeding | ||||||||
Formula | 142 | 2281.5 | 1039 | Referent rate | Referent rate | 484 | Referent rate | Referent rate |
Breastmilk | 145 | 505.5 | 94 | 0.4 (0.3 to 0.5); <0.001 | 1.2 (0.9 to 1.7); 0.28 | 80 | 0.7 (0.6 to 0.9); 0.01 | 0.9 (0.6 to 1.3); 0.47 |
Childcare attendance | ||||||||
No childcare | 150 | 1423.6 | 423 | Referent rate | Referent rate | 242 | Referent rate | Referent rate |
Informal childcare only | 47 | 389.5 | 117 | 1.2 (0.9 to 1.5); 0.13 | 0.8 (0.6 to 1.1); 0.16 | 93 | 1.3 (1.0 to 1.7); 0.10 | 1.3 (0.9 to 1.7); 0.16 |
Formal and/or informal childcare | 90 | 973.8 | 593 | 2.2 (1.9 to 2.5); <0.001 | 1.5 (1.3 to 1.9); <0.001 | 229 | 1.4 (1.1 to 1.7); 0.002 | 1.4 (1.0 to 1.8); 0.03 |
Statistically significant risk ratios and attributable fractions have been highlighted in bold.
*Adjusted for age, sex, type of delivery, gestational age, season, family history, tobacco smoke exposure, household size, maternal education status, mode of feeding and childcare attendance.
†Mother, father or sibling.
OR, odds ratio; VDE, virus detection episode.