Risks of ever and current asthma among adolescents without parental asthma and having attended an indoor pool for<500 h according to their lifetime outdoor pool attendance and their total serum IgE level
| Outdoor pool attendance h | Total serum IgE kIU·L−1 | |||||||||||
| All adolescents¶ | <25 kIU·L−1+ | >25 kIU·L−1§ | >50 kIU·L−1ƒ | >100 kIU·L−1## | ||||||||
| Range | Median# | OR (95% CI) | p-value | OR (95% CI) | p-value | OR (95% CI) | p-value | OR (95% CI) | p-value | OR (95% CI) | p-value | |
| Ever asthma | 0 | 0 | 1.0 (1.0–1.0) | 1.0 (1.0–1.0) | 1.0 (1.0–1.0) | 1.0 (1.0–1.0) | 1.0 (1.0–1.0) | |||||
| >0–100 | 42 | 0.74 (0.24–2.28) | 0.69 | 0.43 (0.05–3.88) | 0.43 | 1.21 (0.33–4.47) | 0.88 | 1.42 (0.36–5.56) | 0.61 | 1.61 (0.38–6.86) | 0.55 | |
| >100–500 | 240 | 2.21 (0.97–5.02) | 0.06 | 0.96 (0.22–4.27) | 0.96 | 3.58 (1.29–9.91) | 0.01 | 3.82 (1.29–11.3) | 0.02 | 5.44 (1.64–18.2) | 0.006 | |
| >500 | 784 | 3.96 (1.60–9.86) | 0.003 | 2.42 (0.51–11.5) | 0.27 | 4.67 (1.50–12.9) | 0.008 | 4.98 (1.51–16.5) | 0.009 | 9.50 (2.46–36.1) | 0.001 | |
| Current asthma | 0 | 0 | 1.0 (1.0–1.0) | 1.0 (1.0–1.0) | 1.0 (1.0–1.0) | 1.0 (1.0–1.0) | 1.0 (1.0–1.0) | |||||
| >0–100 | 42 | 1.19 (0.26–7.57) | 0.40 | 2.18 (0.13–36) | 0.58 | 1.67 (0.33–8.46) | 0.54 | 1.72 (0.34–8.81) | 0.52 | 1.54 (0.30–8.00) | 0.61 | |
| >100–500 | 240 | 3.10 (0.92–10.5) | 0.07 | 0.0 (0–ND) | 0.98 | 4.45 (1.17–16.9) | 0.03 | 4.14 (1.08–15.8) | 0.04 | 4.40 (1.13–17.2) | 0.03 | |
| >500 | 784 | 6.38 (1.78–22.8) | 0.004 | 3.60 (0.22–60.1) | 0.37 | 6.14 (1.47–25.6) | 0.01 | 5.77 (1.37–24.3) | 0.02 | 7.88 (1.77–35.0) | 0.007 | |
Ig: immunoglobulin; OR: odds ratio; CI: confidence interval. #: these values correspond to the whole population included in this analysis (n = 547); ¶: n = 547; +: n = 175; §: n = 372; ƒ: n = 281; ##: n = 184. The numbers of subjects among referents (OR 1.00) and the three pool attendance categories were as follows. Total population: 211, 118, 147 and 71; serum IgE <25 kIU·L−1: 73, 34, 47 and 21; serum IgE >25 kIU·L−1: 138, 84, 100 and 50; serum IgE >50 kIU·L−1: 101, 60, 80 and 40; serum IgE >100 kIU·L−1: 66, 44, 52 and 22. ORs for ever or current asthma calculated on all adolescents were adjusted for total serum IgE, also with the presence of mould on bedroom wall in case of ever asthma. After stratification for serum IgE concentration, ORs for ever asthma were adjusted for the presence of mould on the bedroom wall, the only predictor remaining in the model at p<0.20 (no adjustment was made for serum IgE, as that was the stratification criterion).