Janannii Selvanathan1, Shawn D Aaron2, Jenna R Sykes3, Katherine L Vandemheen2, J Mark FitzGerald4, Martha Ainslie5, Catherine Lemière6, Stephen K Field7, R Andrew McIvor8, Paul Hernandez9, Irvin Mayers10, Sunita Mulpuru2, Gonzalo G Alvarez2, Smita Pakhale2, Ranjeeta Mallick2, Louis-Philippe Boulet11, Samir Gupta12. 1. Keenan Research Center in the Li Ka Shing Knowledge Institute of St. Michael's Hospital, University of Toronto, Toronto, ON, Canada; Institute of Medical Science, University of Toronto, Toronto, ON, Canada. 2. Ottawa Hospital Research Institute, University of Ottawa, Ottawa, ON. 3. Department of Medicine, Division of Respirology, St. Michael's Hospital, Toronto, ON. 4. Centre for Heart and Lung Health, Vancouver Coastal Health Research Institute, Vancouver, BC. 5. Department of Medicine, University of Manitoba, Winnipeg, MB. 6. Department of Medicine, Université de Montréal, Montréal, QC. 7. Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, AB. 8. Firestone Institute for Respiratory Health, McMaster University, Hamilton, ON. 9. Department of Medicine, Dalhousie University, QEII Health Sciences Centre, Halifax, NS. 10. Department of Medicine, University of Alberta, Edmonton, AB. 11. Centre de Recherche, Hopital Laval, Université Laval, Québec, QC, Canada. 12. Keenan Research Center in the Li Ka Shing Knowledge Institute of St. Michael's Hospital, University of Toronto, Toronto, ON, Canada; Department of Medicine, Division of Respirology, St. Michael's Hospital, Toronto, ON. Electronic address: samir.gupta@unityhealth.to.
Abstract
BACKGROUND: In patients with a history suggestive of asthma, diagnosis is usually confirmed by spirometry with bronchodilator response (BDR) or confirmatory methacholine challenge testing (MCT). RESEARCH QUESTION: We examined the proportion of participants with negative BDR testing who had a positive MCT (and its predictors) result and characteristics of MCT, including effects of controller medication tapering and temporal variability (and predictors of MCT result change), and concordance between MCT and pulmonologist asthma diagnosis. STUDY DESIGN AND METHODS: Adults with self-reported physician-diagnosed asthma were recruited by random-digit dialing across Canada. Subjects performed spirometry with BDR testing and returned for MCT if testing was nondiagnostic for asthma. Subjects on controllers underwent medication tapering with serial MCTs over 3 to 6 weeks. Subjects with a negative MCT (the provocative concentration of methacholine that results in a 20% drop in FEV1 [PC20] > 8 mg/mL) off medications were examined by a pulmonologist and had serial MCTs after 6 and 12 months. RESULTS: Of 500 subjects (50.5 ± 16.6 years old, 68.0% female) with a negative BDR test for asthma, 215 (43.0%) had a positive MCT. Subjects with prebronchodilator airflow limitation were more likely to have a positive MCT (OR, 1.90; 95% CI, 1.17-3.04). MCT converted from negative to positive, with medication tapering in 18 of 94 (19.1%) participants, and spontaneously over time in 25 of 165 (15.2%) participants. Of 231 subjects with negative MCT, 28 (12.1%) subsequently received an asthma diagnosis from a pulmonologist. INTERPRETATION: In subjects with a self-reported physician diagnosis of asthma, absence of bronchodilator reversibility had a negative predictive value of only 57% to exclude asthma. A finding of spirometric airflow limitation significantly increased chances of asthma. MCT results varied with medication taper and over time, and pulmonologists were sometimes prepared to give a clinical diagnosis of asthma despite negative MCT. Correspondingly, in patients for whom a high clinical suspicion of asthma exists, repeat testing appears to be warranted.
BACKGROUND: In patients with a history suggestive of asthma, diagnosis is usually confirmed by spirometry with bronchodilator response (BDR) or confirmatory methacholine challenge testing (MCT). RESEARCH QUESTION: We examined the proportion of participants with negative BDR testing who had a positive MCT (and its predictors) result and characteristics of MCT, including effects of controller medication tapering and temporal variability (and predictors of MCT result change), and concordance between MCT and pulmonologist asthma diagnosis. STUDY DESIGN AND METHODS: Adults with self-reported physician-diagnosed asthma were recruited by random-digit dialing across Canada. Subjects performed spirometry with BDR testing and returned for MCT if testing was nondiagnostic for asthma. Subjects on controllers underwent medication tapering with serial MCTs over 3 to 6 weeks. Subjects with a negative MCT (the provocative concentration of methacholine that results in a 20% drop in FEV1 [PC20] > 8 mg/mL) off medications were examined by a pulmonologist and had serial MCTs after 6 and 12 months. RESULTS: Of 500 subjects (50.5 ± 16.6 years old, 68.0% female) with a negative BDR test for asthma, 215 (43.0%) had a positive MCT. Subjects with prebronchodilator airflow limitation were more likely to have a positive MCT (OR, 1.90; 95% CI, 1.17-3.04). MCT converted from negative to positive, with medication tapering in 18 of 94 (19.1%) participants, and spontaneously over time in 25 of 165 (15.2%) participants. Of 231 subjects with negative MCT, 28 (12.1%) subsequently received an asthma diagnosis from a pulmonologist. INTERPRETATION: In subjects with a self-reported physician diagnosis of asthma, absence of bronchodilator reversibility had a negative predictive value of only 57% to exclude asthma. A finding of spirometric airflow limitation significantly increased chances of asthma. MCT results varied with medication taper and over time, and pulmonologists were sometimes prepared to give a clinical diagnosis of asthma despite negative MCT. Correspondingly, in patients for whom a high clinical suspicion of asthma exists, repeat testing appears to be warranted.
Authors: Michael Peled; David Ovadya; Jennifer Cohn; Michael J Segel; Amir Onn; Lior Seluk; Teet Pullerits Journal: BMC Pulm Med Date: 2021-05-06 Impact factor: 3.317
Authors: Andrew Kouri; Samir Gupta; Azadeh Yadollahi; Clodagh M Ryan; Andrea S Gershon; Teresa To; Susan M Tarlo; Roger S Goldstein; Kenneth R Chapman; Chung-Wai Chow Journal: Chest Date: 2020-07-08 Impact factor: 9.410