0-h CPA | >0–20-h CPA | >20-h CPA | ptrend | ||||||
Subjects n/N (%) | OR (95% CI) | Subjects n/N (%) | OR (95% CI) | p-value | Subjects n/N (%) | OR (95% CI) | p-value | ||
Total | 56/235 (23.8) | 1.0 (1.0–1.0) | 29/95(30.5) | 1.24 (0.69–2.23) | 0.46 | 42/100 (42.0) | 2.25 (1.32–3.85) | 0.003 | <0.001 |
Schools with >50% response rate | 35/146 (24.0) | 1.0 (1.0–1.0) | 17/59(28.8) | 1.24 (0.57–2.7) | 0.59 | 23/58 (39.7) | 2.25 (1.10–4.59) | 0.03 | 0.03 |
High parental educational level | 36/156 (23.1) | 1.0 (1.0–1.0) | 22/72(30.6) | 1.31 (0.67–2.57) | 0.43 | 34/82 (41.5) | 2.26 (1.22–4.18) | 0.009 | 0.003 |
Parents with no asthma/respiratory allergies | 17/115 (14.8) | 1.0 (1.0–1.0) | 13/38 (34.2) | 4.31 (1.55–12.0) | 0.005 | 18/45 (40.0) | 4.45 (1.82–10.9) | 0.001 | 0.001 |
No breastfeeding | 19/66 (28.8) | 1.0 (1.0–1.0) | 7/12 (58.3) | 1.06 (0.55–2.06) | 0.86 | 12/22 (54.6) | 2.10 (1.11–3.98) | 0.02 | 0.008 |
No day-care centre attendance | 21/133 (15.8) | 1.0 (1.0–1.0) | 9/32 (28.1) | 2.35 (0.87–6.38) | 0.09 | 15/36 (41.7) | 4.44 (1.88–10.5) | 0.007 | <0.001 |
No maternal smoking during pregnancy | 46/203 (22.7) | 1.0 (1.0–1.0) | 21/77 (27.3) | 1.27 (0.65–2.49) | 0.48 | 34/87 (39.1) | 2.16 (1.20–3.90) | 0.01 | 0.005 |
No exposure to parental smoking | 38/161 (23.6) | 1.0 (1.0–1.0) | 19/65 (29.2) | 1.16 (0.57–2.35) | 0.61 | 32/75 (42.7) | 2.21 (1.18–4.17) | 0.01 | 0.004 |
No older siblings | 16/99 (16.2) | 1.0 (1.0–1.0) | 13/45 (28.9) | 2.26 (0.87–5.88) | 0.09 | 16/47 (34.0) | 2.72 (1.13–6.56) | 0.03 | 0.01 |
No use of bleach for house cleaning | 48/201 (23.9) | 1.0 (1.0–1.0) | 28/87 (32.2) | 1.37 (0.75–2.51) | 0.30 | 36/87 (41.4) | 2.22 (1.25–3.95) | 0.007 | 0.003 |
Odds ratios (ORs) were adjusted for breastfeeding, sex, number of older siblings, area of residence, day-care centre attendance, maternal smoking during pregnancy and parental antecedents of atopic disease (except when the factor was excluded). A high level of education means that the father and/or mother graduated from a university or high school. N: number of subjects in group; CI: confidence interval; ptrend: p-value for trend. #: before the age of 2 yrs.