Past, present and future uses of methacholine testing

Abstract

Methacholine challenge testing is a valuable diagnostic and research tool used by clinicians to assist in the diagnosis of asthma, and by researchers to understand disease pathophysiology and assess novel therapeutic efficacy. The use of methacholine challenge in asthma relates to its direct effect on airway smooth muscle (i.e., bronchoconstriction) as a measure of airway hyperresponsiveness, a cardinal feature of asthma. Airway hyperresponsiveness has been documented in other airway disorders, including chronic obstructive pulmonary disease, cystic fibrosis and allergic rhinitis; however, there is little clinical application of methacholine challenge in these conditions as a diagnostic or disease management tool. The authors will review the aspects of methacholine challenge testing, as they relate to asthma, and point out its usefulness in clinical research. A brief review of past (historical) uses and speculation as to the future uses of methacholine challenge will also be discussed.

Mechanisms of airway hyper‐responsiveness in asthma: the past, present and yet to come

“…This heterogeneity is not always well appreciated. While the clinical utility of AHR has been extensively reviewed elsewhere [5][6][7], we believe that understanding the heterogeneity of the mechanisms underlying AHR is an often over-looked yet important piece of the puzzle. Therefore, we propose that future research into the mechanisms of AHR should aim to move our understanding from a 'one size fits all' approach to ascribing specific mechanisms of AHR to distinct patient populations.…”

Effect of lowering Methacholine Challenge Test cutoff in children

“…The MCT measures airway hyperresponsiveness, and standards have been published. 1,2 The test assesses the provocation concentration that caused a decrease in forced expiratory volume in 1 second (FEV 1 ) of 20% (PC 20 ). 3 Moderate to severe bronchial hyperreactivity is defined as a PC 20 less than 1 mg/mL, mild bronchial hyperreactivity as a PC 20 of 1.0 to 4.0 mg/mL, and borderline bronchial hyperreactivity as a PC 20 of 4.0 to 16.0 mg/mL.…”

The role of airway hyperresponsiveness measured by methacholine challenge test in defining asthma severity in asthma–obesity syndrome

“…However, the authors of a recent review [48] were unable to conclude that bronchial challenge testing was superior to the current outcome measures to determine asthma control. Nonetheless, these authors comment on its indispensable role in research such as assessing treatment efficacy.…”