Interpretation of the “positive” methacholine challenge

Abstract

In cases of inhalation exposure evaluations, alternative explanations must be considered when determining whether a causal association exists between the exposure and a positive methacholine test result.

Airway hyperresponsiveness to mannitol and methacholine and exhaled nitric oxide: A random-sample population study

“…Background rates for asymptomatic AHR to methacholine are reported from less than 10% to greater than 40%, depending on selection and protocol. 20 Female subjects are in general more responsive than male subjects (possibly because of differences in airway caliber), and having 60% girls participating in the study, this might be a contributing factor to this outcome.…”

Effects of Ionized Waterfall Aerosol on Pediatric Allergic Asthma

“…It is a complex disease with a strong genetic component (2), and it is characterized by recurrent episodes of wheezing, variable airway obstruction, and bronchial hyperreactivity (BHR) (3,4). The prevalence of asthma in Austria amounts to 6% of adults and 11% of children (5,6).…”

Exhaled Breath Temperature in Asthmatics and Controls after Eucapnic Voluntary Hyperventilation and a Methacholine Challenge Test

“…The prevalence of positive methacholine challenge tests in the general population has been reported to range from <10% to >40% in various studies, and normal variations in BHR can be expected even among subjects selected for the absence of known potential causes of a positive challenge test, such as asthma [31]. Similar variations are most probable even for indirect tests of BHR, even though they normally display a higher specificity [32].…”