Characteristics of the study centres
| Worldwide | Western Europe | |||
|---|---|---|---|---|
| 13–14 years Mean (range) | 6–7 years Mean (range) | 13–14 years Mean (range) | 6–7 years Mean (range) | |
| WQ, assessed by written questionnaire; VQ, assessed by video questionnaire in 13–14 year olds. | ||||
| Number of study centres | 144 | 81 | 57 | 26 |
| Latitude (degrees) | 36.6 (0.0 to 69.0) | 33.6 (1.0 to 59.0) | 47.2 (32.0 to 69.0) | 43.9 (32.0 to 59.0) |
| Altitude (100 m) | 1.7 (0.0 to 24.5) | 1.2 (0.0 to 23.1) | 1.0 (0.0 to 6.6) | 1.1 (0.1 to 6.6) |
| Climatic factors | ||||
| Annual outdoor temperature (°C) | 15.7 (−1.3 to 28.5) | 17.4 (1.8 to 28.5) | 12.3 (−1.3 to 18.5) | 13.8 (6.6 to 18.5) |
| Annual outdoor relative humidity (%) | 72.0 (48.6 to 87.6) | 71.8 (48.6 to 87.6) | 73.9 (57.0 to 83.1) | 73.0 (57.0 to 83.1) |
| Annual indoor relative humidity at 20°C (%) | 61.8 (28.0 to 125.6) | 67.4 (28.0 to 125.6) | 49.0 (31.1 to 67.4) | 52.2 (34.8 to 67.4) |
| Prevalence (in %) of symptoms in the last year | ||||
| Asthma symptoms (WQ) | 14.6 (1.8 to 36.7) | 11. 9 (1.5 to 27.2) | 16.7 (2.7 to 36.7) | 8.5 (3.5 to 18.4) |
| Asthma symptoms (VQ) | 7.5 (0.7 to 19.6) | – | 6.2 (3.8 to 9.8) | – |
| Rhinitis symptoms | 13.7 (1.6 to 39.7) | 6.9 (1.5 to 14.9) | 14.7 (6.2 to 25.5) | 5.7 (3.5 to 11.2) |
| Eczema symptoms | 7.6 (0.1 to 19.9) | 7.2 (0.7 to 18.4) | 9.3 (1.8 to 18.9) | 6.6 (2.6 to 18.4) |