Upper airway hyperresponsiveness To methacholine in patients with suspected asthma

Choi, Inseon S; Kang, Kwang Won; Koh, Youngil I; Hong, Seo Na

Abstract

BACKGROUND: Upper airway diseases, such as vocal cord dysfunction (VCD), masquerade as asthma. Bronchial hyperresponsiveness (BHR) to methacholine (MCh) has been demonstrated in only part of suspected asthma patients. Investigators have shown upper airway hyperresponsi- veness (UHR) in patients with VCD.
OBJECTIVE
To determine the clinical importance of UHR and to evaluate the usefulness of UHR test in patients with suspected asthma.
METHODS
Thirty-six consecutive patients with suspected asthma underwent a MCh inhalation challenge. BHR was determined with PC20 < 8 mg/ml, UHR with a decrease in MIF50 > 25% from the baseline, and upper airway obstruction (UAO) with MEF50/MIF50 > 1.
RESULTS
Only 17 patients (47.2%) showed BHR. Also, the same proportion of subjects showed UHR, and the each combination of BHR/UHR was nearly equal in distribution (9 BHR+/UHR-, 8 BHR+/UHR+, 9 BHR-/UHR+, and 10 BHR-/UHR-). Patients with BHR-/UHR+ had significantly lower serum total IgE level than those with BHR-/UHR-. Eight patients with UHR and UAO showed significantly shorter duration of disease (p < 0.05), smaller numbers of atopy family history (p < 0.05), and lower serum total IgE level than the others (p < 0.05).
CONCLUSION
Many patients with suspected asthma showed UHR, and about half of patients with negative MCh-BHR showed UHR that might be related to non-asthmatic diseases including VCD. Therefore, a routine UHR test may be warranted in detecting upper airway diseases in suspected asthma.