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Two-tiered methacholine challenge test proposed for asthma diagnosis

The administration of a two-tiered methacholine challenge test is an accurate, time-saving method that also avoids decreased forced expiratory volume in 1 second, according to results from a retrospective study.

According to the literature, the subsequent results of the methacholine challenge test (MCT) act as a stimulus in which forced expiratory volume in 1 second (FEV₁) decreases by 20% (PC₂₀). Michael J. Segel, MD, of the Pulmonary Institute at Chaim Sheba Medical Center at Tel Hashomer and Tel-Aviv University Sackler Medical School in Israel, and colleagues conducted a retrospective analysis of 879 consecutive MCTs.

The instance at which the FEV₁ decreases by 10% (PC₁₀), a cutoff of 1 mg/mL or less demonstrated a sensitivity of 86%, a specificity of 98%, a positive predictive value of 97%, and a negative predictive value of 91% vs. a PC₂₀ cutoff of less than 8 mg/mL, according to data.

“We propose a two-tiered protocol. A lower PC₁₀ cutoff of 1 mg/mL or less is used to ‘rule in’ [bronchial hyper-responsiveness] at lower methacholine concentrations than would have been possible using the existing protocol, with minimal compromise of accuracy. Most FEV₁ decreases greater than 40% below baseline would be avoided by the proposed novel protocol, thus enhancing patient and staff comfort. In addition, there is a modest saving in time,” the researchers wrote.

They said the proposed method would allow an avoidance of 26 of 42 cases (62%), confirming a time-saving aspect to the protocol.

Disclosure: The researchers report no relevant financial disclosures.