Methacholine challenge testing: improved patient comfort with a 2-tiered protocol.

Michael J Segel, Einat Rabinovich, Yehuda Schwarz, Issahar Ben-Dov

Pulmonary Institute, Chaim Sheba Medical Center, Tel Hashomer, Israel. Michael.Segel@gmail.com

Annals of allergy, asthma & immunology : official publication of the American College of Allergy, Asthma, & Immunology 2013 Jun

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The methacholine challenge test (MCT) is a test of bronchial hyperreactivity used as an aid in the diagnosis of asthma. MCT results are reported as the provocation concentration at which the forced expiratory volume in 1 second (FEV1) decreases 20% (PC20). The requirement for a 20% or greater decrease in FEV1 results in precipitous decreases in FEV1 in some patients. To improve MCT safety without compromising accuracy. We performed a retrospective analysis of 879 consecutive MCTs (derivation cohort). A novel protocol for MCT was developed and validated in a cohort of 564 MCTs performed in a second institution. In comparison with a PC20 cutoff of less than 8 mg/mL, a provocation concentration at which the FEV1 decreases 10% (PC10) cutoff of 1 mg/mL or less has a sensitivity of 86%, a specificity of 98%, a positive predictive value (PPV) of 97%, and a negative predictive value (NPV) of 91%. We propose a novel 2-tiered protocol for MCT. If the PC10 is 1 mg/mL or less, bronchial hyperreactivity is present; if the PC10 is greater than 1 mg/mL, the test is continued until the provocative concentration is 8 mg/mL or a 20% decrease in FEV1 is achieved. Compared with the standard protocol, the proposed protocol has a sensitivity, specificity, PPV, NPV, and overall accuracy of 100%, 98%, 97.6%, 100%, and 99%, respectively. The modified protocol would have enabled us to avoid 26 of 42 cases (62%) in which a 40% or greater decrease in FEV1 occurred and would save 0.65 dose for every MCT performed. The 2-tiered protocol performed well in the validation cohort; sensitivity, specificity, PPV, NPV, and overall accuracy were 100%, 98%, 87%, 100%, and 98%, respectively. The proposed 2-tiered protocol is accurate, saves time, and avoids precipitous decreases in FEV1. Copyright © 2013 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Citation

Michael J Segel, Einat Rabinovich, Yehuda Schwarz, Issahar Ben-Dov. Methacholine challenge testing: improved patient comfort with a 2-tiered protocol. Annals of allergy, asthma & immunology : official publication of the American College of Allergy, Asthma, & Immunology. 2013 Jun;110(6):429-32