Association between spirometric lung function and proportion of days with respiratory symptoms present during a 2–3‐month follow-up among children with chronic respiratory symptoms. Odds ratios and 95% confidence intervals adjusted for age, sex, study centre, atopy, and symptom status (having asthma or not)
| Subjects n | Lower respiratory symptoms# | Upper respiratory symptoms¶ | Cough | Phlegm | |||||
| % of days | OR (CI) | Days % | OR (CI) | Days % | OR (CI) | Days % | OR (CI) | ||
| FVC, % from predicted | |||||||||
| >109.1 | 443 | 7.1 | 1.0 | 30.8 | 1.0 | 25.6 | 1.0 | 12.4 | 1.0 |
| 99.9–109.1 | 442 | 7.0 | 1.00 (0.79, 1.28) | 31.3 | 1.06 (0.88, 1.27) | 26.7 | 1.12 (0.93, 1.34) | 12.3 | 1.22 (0.98, 1.52) |
| 91.9–99.9 | 441 | 7.2 | 0.98 (0.76, 1.27) | 29.8 | 1.09 (0.90, 1.31) | 26.8 | 1.21 (1.00, 1.46) | 9.9 | 0.96 (0.75, 1.22) |
| <91.9 | 443 | 6.2 | 0.88 (0.67, 1.15) | 30.7 | 1.12 (0.92, 1.36) | 25.5 | 1.07 (0.88, 1.29) | 11.0 | 1.18 (0.93, 1.49) |
| FEV1, % from predicted | |||||||||
| >112.5 | 438 | 6.2 | 1.0 | 29.4 | 1.0 | 25.6 | 1.0 | 10.4 | 1.0 |
| 104.0–112.5 | 438 | 6.3 | 0.96 (0.74, 1.25) | 30.4 | 1.11 (0.92, 1.33) | 26.1 | 1.06 (0.88, 1.27) | 12.0 | 1.25 (0.99, 1.58) |
| 95.4–104.0 | 437 | 6.9 | 0.97 (0.74, 1.26) | 31.7 | 1.19 (0.98, 1.44) | 28.0 | 1.22 (1.01, 1.47) | 12.6 | 1.47 (1.16, 1.85) |
| <95.4 | 438 | 8.3 | 1.28 (0.99, 1.66) | 31.2 | 1.17 (0.96, 1.42) | 25.3 | 1.09 (0.90, 1.32) | 10.8 | 1.30 (1.01, 1.67) |
| MMEF, % from predicted | |||||||||
| >113.5 | 444 | 5.5 | 1.0 | 28.6 | 1.0 | 24.3 | 1.0 | 8.8 | 1.0 |
| 96.4–113.5 | 445 | 5.8 | 1.00 (0.76, 1.32) | 29.9 | 0.97 (0.80, 1.18) | 24.1 | 1.04 (0.86, 1.26) | 10.9 | 1.36 (1.06, 1.75) |
| 80.4–96.4 | 443 | 6.1 | 0.91 (0.68, 1.20) | 31.2 | 1.09 (0.90, 1.32) | 27.8 | 1.24 (1.02, 1.50) | 12.5 | 1.55 (1.21, 1.99) |
| <80.4 | 443 | 10.3 | 1.51 (1.16, 1.94) | 32.9 | 1.06 (0.87, 1.28) | 28.6 | 1.25 (1.03, 1.52) | 13.7 | 1.59 (1.24, 2.05) |
| FEV1/FVC, % | |||||||||
| >93 | 465 | 5.0 | 1.0 | 29.1 | 1.0 | 25.4 | 1.0 | 10.2 | 1.0 |
| 88–93 | 463 | 6.3 | 1.12 (0.85, 1.47) | 30.0 | 0.96 (0.79, 1.15) | 26.7 | 1.09 (0.90, 1.31) | 10.6 | 1.04 (0.82, 1.32) |
| 83–88 | 463 | 7.5 | 1.27 (0.97, 1.66) | 32.9 | 1.13 (0.94, 1.37) | 26.9 | 1.20 (0.99, 1.45) | 12.5 | 1.20 (0.95, 1.53) |
| <83 | 463 | 8.9 | 1.41 (1.07, 1.85) | 30.2 | 0.98 (0.81, 1.19) | 25.7 | 1.10 (0.90, 1.34) | 12.7 | 1.30 (1.02, 1.66) |
OR: odds ratio
CI: confidence interval
FVC: forced vital capacity
FEV1: forced expiratory volume in one second
MMEF: maximal mid-expiratory flow
#: shortness of breath, wheeze, or attacks of shortness of breath with wheeze
¶: stuffed/runny nose, sore throat