Methacholine challenge test: Diagnostic characteristics in asthmatic patients receiving controller medications - 27/06/12
, Elizabeth A. Sugar, PhD b, Charles G. Irvin, PhD c, David A. Kaminsky, MD c, Dave Shade, JD b, Christine Y. Wei, MS b, Janet T. Holbrook, PhD, MPH b, Robert A. Wise, MD d, Mario Castro, MD, MPH aAmerican Lung Association Asthma Clinical Research Centers
Corresponding author: Kaharu Sumino, MD, MPH, Washington University School of Medicine, 660 Euclid Ave, Campus Box 8052, St Louis, MO 63110.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 PC20 (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 PC20 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.
Le texte complet de cet article est disponible en PDF.Key words : Asthma diagnosis, inhaled corticosteroids, race, atopy
Abbreviations used : AHR, ATS, ICS, MCT
Plan
| ClinicalTrials.gov identifier NCT00705341. |
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| Supported by the American Lung Association. Drugs were donated by Methapharm (Provocholine) and GlaxoSmithKline (Ventolin HFA and Flovent). Neither Methapharm nor GlaxoSmithKline played any role in the design, conduct, data analysis, or interpretation of the study. |
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| Disclosure of potential conflict of interest: K. Sumino receives research support from the National Institutes of Health, the US Department of Veterans Affairs, and the American Lung Association. E. A. Sugar receives research support from the American Lung Association, Methapharm, and GlaxoSmithKline. C. G. Irvin is on the speakers’ bureau for Merck, has consultant arrangements with Methapharm, and receives research support from the National Institutes of Health and the American Lung Association–Asthma Clinical Research Center. D. A. Kaminsky is on the American Thoracic Society Proficiency Standards Committee. J. T Holbrook receives research support from the American Lung Association, Methapharm, and GlaxoSmithKline. R. A. Wise has consultant arrangements with and is an advisor for GlaxoSmithKline, Boehringer-Ingelheim, AstraZeneca, Novartis, and Pfizer and receives research support from the American Lung Association, the National Institutes of Health, GlaxoSmithKline, and Boehringer-Ingelheim. M. Castro has consultant arrangements with Asthmatx; is on the speakers’ bureau for Asthmatx, Genentech, Astra-Zeneca, Merck, and GlaxoSmithKline; is on an Advisory Board for Genentech; receives royalties from Elsevier; and receives research support from Asthmatx, Amgen, Ception/Cephalon, Genentech, MedImmune, Merck, Novartis, the National Institutes of Health, and GlaxoSmithKline. The rest of the authors declare that they have no relevant conflicts of interest. |
Vol 130 - N° 1
P. 69 - juillet 2012 Retour au numéro
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