Measures of Perception of Bronchoconstriction and Clinical and Functional Data Are Not Interrelated in Asthma

Abstract

Background: Sensitivity and absolute perceptual magnitude characterize the perception of bronchoconstriction (PB). Objectives: To define whether clinical and functional characteristics and level of bronchial hyperresponsiveness (BHR) correlate with these two PB indexes during bronchial challenge in asthma. Methods: PB on both the Borg scale and the visual-analogue scale (VAS) was assessed in 45 consecutive asthmatics during a methacholine-induced decrease in forced expiratory volume in 1 s (FEV₁) and specifically quantified as Borg and VAS slope, as a measure of sensitivity, whereas scores at a 20% FEV₁ decrease (PB₂₀) were assessed as a measure of absolute perceptual magnitude. Clinical score and BHR were also assessed. Results: PB₂₀ related to slope on both the Borg scale and the VAS (p < 0.0001). PB₂₀ and slope related neither to clinical score nor to baseline functional data on both scales. The relationship between the level of BHR and PB₂₀ on either scale was of questionable clinical significance (r² = 7%). Conclusions: Irrespective of the scale employed, our data indicate the need for directly assessing PB rather than deriving it from clinical and functional data and level of BHR.