| Visit 1# | Visit 2¶ | Visit 3# | Visit 4¶ | p-value | |
| Spirometry | |||||
| FEV1 % | 102 (85.5–110) | 99.5 (90.8–110) | 95 (86–103) | 96 (86.5–105) | 0.010 |
| FEV1/FVC | 0.78 (0.73–0.84) | 0.80 (0.75–0.85) | 0.79 (0.74–0.83) | 0.80 (0.76–0.84) | 0.092 |
| FEF25–75% | 79.5 (61–105) | 83 (63–108) | 76 (63–95) | 77 (64–101) | >0.100 |
| ΔFEV1 % | 7 (3–14.5) | 6 (3–13) | 7.5 (5–13) | 7 (3–11) | >0.100 |
| Inflammation | |||||
| FeNO ppb | 12 (8–22.5) | 18.5 (10–27.3) | 20 (12–38.3) | 16 (8–42) | 0.001 |
| pH EBC | 8.41 (8.23–8.50) | 8.06 (7.71–8.26) | 7.76 (7.05–8.11) | 8.07 (7.48–8.27) | 0.001 |
| Clinical outcomes+ | |||||
| Wheezing | 46 (90) | 27 (53) | 22 (43.1) | 20 (39.2) | 0.001 |
| Rescue medication | 27 (53) | 19 (37.7) | 19 (37.7) | 18 (35.3) | 0.068 |
| Emergency department | 16 (31.3) | 9 (17) | 6 (11.8) | 4 (7.8) | 0.006 |
Data are presented as median (interquartile range) or n (%), unless otherwise stated. FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; FEF25–75%: forced expiratory flow between 25–75% of FVC; ΔFEV1: increase of FEV1 as a percentage of the initial value after bronchodilator; FeNO: exhaled nitric oxide fraction; EBC: exhaled breath condensate. #: visits in January; ¶: visits in June; +: clinical outcomes concern the previous 6 months.