Factors for the Variability of Three Acceptable Maximal Expiratory Flow–Volume Curves in Chronic Obstructive Pulmonary Disease
Received 2 October 2020
Accepted for publication 30 December 2020
Published 24 February 2021 Volume 2021:16 Pages 415—422
Checked for plagiarism Yes
Review by Single anonymous peer review
Peer reviewer comments 2
Editor who approved publication: Dr Richard Russell
Masafumi Yamamoto,1 Satoshi Konno,2 Hironi Makita,2,3 Katsuaki Nitta,4 Kaoruko Shimizu,2 Masaru Suzuki,2 Mutsumi Nishida,1 Junichi Sugita,1 Takanori Teshima,1 Masaharu Nishimura2,3
1Division of Laboratory and Transfusion Medicine, Hokkaido University Hospital, Sapporo, Hokkaido, Japan; 2Department of Respiratory Medicine, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan; 3Hokkaido Institute of Respiratory Diseases, Sapporo, Hokkaido, Japan; 4Makita Hospital, Sapporo, Hokkaido, Japan
Correspondence: Masaharu Nishimura
Department of Respiratory Medicine, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, N-15 W-7, Kita-Ku, Sapporo, 060-8638, Japan
Background: Generally, the maximal expiratory flow–volume (MEFV) curve must be measured for the diagnosis and staging of chronic obstructive pulmonary disease (COPD). As this test is effort dependent, international guidelines recommend that three acceptable trials are required for each test. However, no study has examined the magnitude and factors for the variability in parameters among three acceptable trials.
Methods: We evaluated the intra-individual variations in several parameters among three acceptable MEFV curves obtained at one-time point in patients with COPD (n = 28, stage 1; n = 36, stage 2; n = 21, stages 3– 4). Next, the factors for such variations were examined using forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC).
Results: The averages of coefficient of variation (CV) for FEV1 and FVC were 2.0% (range: 1.0– 3.0%) and 1.6% (0.9– 2.2%), respectively. Both parameters were significantly better than peak expiratory flow rate, forced expiratory flow at 50% of expired FVC, and forced expiratory flow at 75% of expired FVC (CVs: 5.0– 6.9%). A higher spirometric stage was significantly associated with higher CVs for FVC and FEV1, and older age was significantly correlated with a higher variation in FEV1 alone. Furthermore, a significantly inverse association was observed between emphysema severity, and the CVs for FEV1, but not that for FVC, regardless of spirometric stage.
Conclusion: Both FVC and FEV1 are highly reproducible; nevertheless, older age, lower FEV1 at baseline, and non-emphysema phenotype are factors for a higher variability in FEV1 in patients with COPD.
Keywords: chronic obstructive pulmonary disease, coefficient of variation, flow–volume curve, forced expiratory volume in 1 second, variability
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