Methacholine challenge test: Diagnostic characteristics in asthmatic patients receiving controller medications

Kaharu Sumino, Elizabeth A. Sugar, Charles G. Irvin, David A. Kaminsky, Dave Shade, Christine Y. Wei, Janet T. Holbrook, Robert A. Wise, Mario Castro

Research output: Contribution to journalArticle

Abstract

Background: The methacholine challenge test (MCT) is commonly used to assess airway hyperresponsiveness, but the diagnostic characteristics have not been well studied in asthmatic patients receiving controller medications after the use of high-potency inhaled corticosteroids became common. Objectives: We investigated the ability of the MCT to differentiate participants with a physician's diagnosis of asthma from nonasthmatic participants. Methods: We conducted a cohort-control study in asthmatic participants (n = 126) who were receiving regular controller medications and nonasthmatic control participants (n = 93) to evaluate the sensitivity and specificity of the MCT. Results: The overall sensitivity was 77% and the specificity was 96% with a threshold PC 20 (the provocative concentration of methacholine that results in a 20% drop in FEV1) of 8 mg/mL. The sensitivity was significantly lower in white than in African American participants (69% vs 95%, P =.015) and higher in atopic compared with nonatopic (82% vs 52%, P =.005). Increasing the PC 20 threshold from 8 to 16 mg/mL did not noticeably improve the performance characteristics of the test. African American race, presence of atopy, and lower percent predicted FEV1 were associated with a positive test result. Conclusions: The utility of the MCT to rule out a diagnosis of asthma depends on racial and atopic characteristics. Clinicians should take into account the reduced sensitivity of the MCT in white and nonatopic asthmatic patients when using this test for the diagnosis of asthma.

Original languageEnglish (US)
Pages (from-to)69-75.e6
JournalJournal of Allergy and Clinical Immunology
Volume130
Issue number1
DOIs
StatePublished - Jul 2012

Keywords

  • Asthma diagnosis
  • atopy
  • inhaled corticosteroids
  • race

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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