Background: There is no obvious link between qualitative descriptors and overall intensity of dyspnea during bronchoconstriction in patients with asthma.
Aims: To determine whether qualitative and quantitative perception of methacholine-induced bronchoconstriction independently contribute to characterizing clinically stable asthma.
Material and methods: We assessed changes in inspiratory capacity, and quantitative (by Borg scale) and qualitative (by a panel of eight dyspnea descriptors) sensations of dyspnea at 20 to 30% fall in FEV1 during methacholine inhalation in 49 asthmatics. Furthermore, we calculated the level of perception of bronchoconstriction at 20% fall in FEV1 (PB20).
Results: Descriptors selected by patients during methacholine inhalation allowed us to define three language subgroups: (1) chest tightness (subgroup A, n = 21); (2) work/effort (subgroup B, n = 7); and (3) both descriptors (subgroup C, n = 13). Eight of the 49 patients (subgroup D) were not able to make a clear-cut distinction among descriptors. The subgroups exhibited similar function at baseline and during methacholine inhalation. Most importantly, patients selected chest tightness to a greater extent (42.85%), and work/effort (14.3%) and both descriptors (26.5%) to a lesser extent at the lowest level of bronchoconstriction (FEV1 fall < 10%) as at 20% fall in FEV1. Thirty-two patients were normoperceivers (PB20 ≥ 1.4 to < 5 arbitrary units [au]), 7 patients were hyperperceivers (PB20 ≥ 5 au), and 10 patients were hypoperceivers (PB20 < 1.4 au). Language subgroups were equally distributed across the perceiver subgroups.
Conclusions: In patients with clinically stable asthma, PB20 and language of dyspnea independently contribute to defining the condition of the disease. However, the possibility that this independence may be due to a β-error should be taken into account.