Longitudinal change of FEV1 and inspiratory capacity: clinical implication and relevance to exacerbation risk in patients with COPD

Yong Suk Jo,1 Sung Kyoung Kim,2 Seoung Ju Park,3 Soo-Jung Um,4 Yong-Bum Park,5 Ki Suck Jung,6 Deog Kyeom Kim,7 Kwang Ha Yoo8 1Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, Kyung Hee University Hospital, Seoul, Republic of Korea; 2Department of Internal Medicine, Division of Pulmonology, St Vincent’s Hospital, The Catholic University of Korea, Seoul, Republic of Korea; 3Department of Internal Medicine, Chonbuk National University Medical School, Jeonju, Republic of Korea; 4Department of Internal Medicine, Division of Pulmonology, Dong-A University Hospital, Busan, Republic of Korea; 5Department of Internal Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, Hallym University Kangdong Sacred Heart Hospital, Seoul, Republic of Korea; 6Department of Internal Medicine, Division of Pulmonary Medicine, Hallym University Sacred Heart Hospital, Hallym University Medical School, Anyang, Republic of Korea; 7Department of Internal Medicine, Seoul Metropolitan Government, Seoul National University Boramae Medical Center, Seoul, Republic of Korea; 8Department of Internal Medicine, Division of Pulmonary and Allergy Medicine, Konkuk University School of Medicine, Seoul, Republic of Korea Background and objective: FEV1 is the gold standard for assessment of COPD. We compared efficacy of FEV1, inspiratory capacity (IC), and IC to total lung capacity (TLC) ratio in the evaluation of COPD and their association with exacerbation.Methods: We analyzed the association of dyspnea severity, quality of life status, and lung function with lung function measurements and exacerbation risk in 982 patients enrolled in the Korea COPD Subgroup Registry and Subtype Research study. Exacerbation and longitudinal lung function change were evaluated in 3 years’ follow-up.Results: The FEV1, IC, and IC to TLC ratio showed comparable negative correlations with dyspnea severity and quality of life status, and positive correlation with exercise capacity. In patients with >2 events/year, annual rate of change in FEV1 and IC tended to decline more rapidly in those with FEV1 <50% than in those with FEV1 >50% (-14.46±19.40 mL/year vs 12.29±9.24 mL/year, P=0.213; -4.75±17.28 mL/year vs -78.05±34.16 mL/year, P=0.056 for FEV1 and IC, respectively), without significance.Conclusion: Longitudinal changes in IC and FEV1 were not significantly associated with exacerbation risk. Keywords: COPD, exacerbation, FEV1, inspiratory capacit