Table 3.

Explanatory models for symptom variability with methacholine.

	Mild obstruction	Moderate obstruction
Dyspnea	R5 (r2 = 0.10)	X5_IQR (r2 = 0.12)
Chest tightness	R5‐int + (r2 = 0.15)	None
Inspiratory effort	R5‐19_IQR (r2 = 0.13)	X5_IQR (r2 = 0.18)
Unrewarded inspiration	R5‐slope (r2 = 0.07)	X5‐int (r2 = 0.07)
Expiratory difficulty	None	None

R₅ and X₅, respiratory resistance and reactance at 5 Hz, respectively; R_5‐19, difference between R at 5 and 19 Hz; R_5‐int, X_5‐int, and R_5‐slope, intercepts and slope of the linear regression analysis of the postdeep inspiration R₅ and X₅ plotted versus time (see also Fig. 1); R_{5‐19_IQR} and X₅__IQR, interquartile ranges of the probability density estimation of R_5‐19 and X₅.