Diagnostic properties of the methacholine and mannitol bronchial challenge tests: a comparison study.

Abstract

BACKGROUND AND OBJECTIVE: Airway hyperresponsiveness is a common feature of

asthma. Methacholine and mannitol are two representative agonists for bronchial

challenge. They have theoretically different mechanisms of action, and may have

different diagnostic properties. However, their difference has not been directly

evaluated among Korean adults. In this study, we compare the diagnostic

properties of methacholine and mannitol bronchial provocation tests. METHODS:

Asthmatic patients and non-asthmatic controls were recruited prospectively from

four referral hospitals in Korea. Participants were challenged with each of

methacholine and mannitol inhalation on different days. Their diagnostic utility

was evaluated by calculating their sensitivity and specificity for asthma

diagnosis. Response-dose ratio was also compared. RESULTS: A total of 50

asthmatic adults and 54 controls were enrolled (mean age 43.8 years). The

sensitivity and specificity of mannitol challenge (defined by a PD15 of <635 mg)

were 48.0% and 92.6%, respectively, whereas those of methacholine (defined by a

PC20 of <16 mg/mL) were 42.0% and 98.1%, respectively. Twenty asthmatic

participants (24%) showed positive response to a single agonist only. In the

receiver operating curve analyses using response-dose ratio values, area under

the curve was 0.77 (95% confidence interval (CI): 0.68-0.86) for mannitol, and

0.89 (95% CI: 0.83-0.95) for methacholine. The correlations between log-

transformed mannitol and methacholine response-dose ratios were significant but

moderate (r = 0.683, P < 0.001). CONCLUSIONS: The present study demonstrated

overall similar diagnostic properties of two diagnostic tests, but also suggested

their intercomplementary roles for asthma. The clinical trial registration number

at ClinicalTrial.gov is NCT02104284.