Scientific Publications Database

Article Title: Between-Visit Variability in FEV1 as a Diagnostic Test for Asthma in Adults
Authors: Dean, Benjamin W.; Birnie, Erin E.; Whitmore, George Alex; Vandemheen, Katherine L.; Boulet, Louis-Philippe; FitzGerald, J. Mark; Ainslie, Martha; Gupta, Samir; Lemiere, Catherine; Field, Stephen K.; McIvor, R. Andrew; Hernandez, Paul; Mayers, Irvin; Aaron, Shawn D.
Journal: ANNALS OF THE AMERICAN THORACIC SOCIETY Volume 15 Issue 9
Date of Publication:2018
Abstract:
Rationale: The reliability of using between-visit variation in forced expiratory volume in 1 second (FEV1) to diagnose asthma is understudied, and hence uncertain.Objective: To determine whether FEV1 variability measured over recurrent visits is significantly associated with a diagnosis of current asthma.Methods: Randomly selected adults (N = 964) with a history of physician-diagnosed asthma were studied from 2005 to 2007 and from 2012 to 2016. A diagnosis of current asthma was confirmed in those participants who exhibited bronchial hyperresponsiveness to methacholine and/or acute worsening of asthma symptoms while being weaned off asthma medications. Regression analyses and receiver operating curves were used to evaluate the ability of between-visit FEV1 variability to diagnose asthma.Results: A current diagnosis of asthma was confirmed in 584 of 964 participants (60%). Between-visit absolute variability in FEV1 was significantly greater in those in whom current asthma was confirmed, compared with those in whom current asthma was ruled out (7.3% vs. 4.8%; mean difference between the two groups, 2.5%; 95% confidence interval, 1.7-3.3%). However, a 12% and 200-ml between-visit variation in FEV1, which is the diagnostic threshold recommended by Global Initiative for Asthma, exhibited a sensitivity of only 0.17 and a specificity of 0.94 for confirming current asthma. A between-visit absolute variability in FEV1 >= 12% and 200 ml increased the pretest probability of asthma from 60% to a posttest probability of 81%.Conclusions: A 12% and 200-ml between-visit variation in FEV1, if present, has reasonably good specificity for diagnosing asthma, but has poor sensitivity compared with bronchial challenge testing. Between-visit variability in FEV1 is a relatively unhelpful test to establish a diagnosis of asthma.