Obstructive Lung Diseases: Obstructive Lung Disease Diagnosis and Misdiagnosis |

Residual Volume Reversibility Is a Better Test in Identifying Reversible Airway Disease Compared to FEV1 Reversibility in Patients With Chronic Persistent Asthma FREE TO VIEW

Sasan Sazgar, MD; Ali Rashidian, MD; Belayneh Abejie, MD; Vipul Jain, MD; Jose Vempilly, MD
Author and Funding Information

UCSF Fresno, Division of Pulmonary & Critical Care Medicine, Fresno, CA

Copyright 2016, American College of Chest Physicians. All Rights Reserved.

Chest. 2016;150(4_S):919A. doi:10.1016/j.chest.2016.08.1019
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SESSION TITLE: Obstructive Lung Disease Diagnosis and Misdiagnosis

SESSION TYPE: Original Investigation Slide

PRESENTED ON: Wednesday, October 26, 2016 at 07:30 AM - 08:30 AM

PURPOSE: Documentation of significant FEV1 reversibility as defined by ATS has been the cornerstone for diagnosing reversible airway obstruction in asthma. All drug trials for asthma mandate significant FEV1 reversibility as criteria for recruitment. However, only about 30% of patients with asthma have significant reversible airway disease. Therefore, we explored the utility of performing lung volume reversibility in addition to spirometry testing in patients with persistent asthma.

METHODS: Adult subjects with physician-diagnosed asthma and persistent symptoms on treatment were recruited prospectively after obtaining an informed consent. Patients were recruited based on the strict concurrence of meeting inclusion criteria and not meeting any exclusion criteria. Spirometry and Lung volume measurements were done using plethysmography with reversibility testing according to ATS /ACCP recommendations. FEV1 and RV reversibility Correlation analysis was determined using Pearson’s coefficient. The proportion of patients with significant reversibility was compared using RV reversibility and FEV1 reversibility by Chi-square analysis. All analyzes were done using SPSS version 23. A p-value <0.05 was considered statistically significant.

RESULTS: Among the 123 subjects recruited, 75.6% were women. The ethnicity was Caucasian in 64.2 %, Hispanic in 22.8 %, and African American in 13.0% of subjects. There were 5.7% smokers With less than 6 mean pack-year of smoking. The mean age of patients was 52 ± 15 years. The mean duration of asthma was 17± 15 years. Among the 123 patients 58 (47%) had neither RV nor FEV1 reversibility, 12% were both RV and FEV1 reversible. Of the 69 subjects with no RV reversibility, 11 patients (16%) were FEV1 reversible. Among the 69 with RV reversibility 50 patients (72%) were not FEV1 reversible. The mean RV reversibility was 8.2 and, therefore, a significant RV reversibility was identified as 10.2% as described previously for significant FEV1 reversibility. The total number of patients with RV reversibility 54(44%) was significantly more compared to patients with FEV1 reversibility 26 (21%) (p=0.0002). Furthermore, there was only mild correlation between FEV1 reversibility and RV reversibility (r=0.25)

CONCLUSIONS: RV reversibility as a test identified significantly more patients with reversible airway disease in asthma compared to FEV1 reversibility. Minimal correlation between FEV1 and RV reversibility suggests an independent mechanism for RV reversibility in asthma.

CLINICAL IMPLICATIONS: The addition of RV reversibility testing to standard spirometry can potentially improve the diagnosis of reversible airway disease in asthma. Performing RV reversibility can reduce the number of patients subjected to Methacholine challenge in the absence of significant FEV1 reversibility. Furthermore, the inclusion of patients with RV reversibility in addition to FEV1 reversibility can facilitate drug trial recruitment.

DISCLOSURE: The following authors have nothing to disclose: Sasan Sazgar, Ali Rashidian, Belayneh Abejie, Vipul Jain, Jose Vempilly

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