Airway responsiveness(AR) to methacholine with regard to baseline lung function
| Baseline lung function | AR to methacholine | p-value+ | |
| Mild or no AR# | Increased AR¶ | ||
| FRC z-score | 0.4 (-1.5–4.8) | 0.3 (-1.8–4.8) | 0.809 |
| ≥2 | 1 (3) | 13 (23) | 0.010 |
| V′max,FRC z-score | -0.5 (-2.7–0.8) | -1.4 (-3.0–1.4) | 0.002 |
| ≤-2 | 3 (9) | 13 (23) | 0.083 |
Data are presented as median (range) and n (%). FRC: functional residual capacity; V′max,FRC: maximal expiratory flow at functional residual capacity. #: provocative dose of methacholine causing a 40% fall in forced expiratory flow at functional residual capacity (PD40 V′max,FRC) >0.90 mg (n = 34); ¶: PD40 V′max,FRC ≤0.90 mg (n = 56); +: univariate analyses, performed by Chi-squared test (dichotomous variables), or by Mann–Whitney U-test (continuous variables).