Impact of symptom variability on clinical outcomes in COPD: analysis of a longitudinal cohort
Received 31 January 2019
Accepted for publication 1 August 2019
Published 20 September 2019 Volume 2019:14 Pages 2135—2144
Checked for plagiarism Yes
Review by Single anonymous peer review
Peer reviewer comments 3
Editor who approved publication: Dr Richard Russell
Mi-Ae Kim,1 Min-Kang Suh,1 Jisoo Park,1 Jung-Hyun Kim,1 Tae-Hoon Kim,1 Eun Kyung Kim,1 Yeon-Mok Oh,2 Sang-Do Lee,2 Ji-Hyun Lee1
1Department of Pulmonology, Allergy and Critical Care Medicine, CHA Bundang Medical Center, CHA University, Seongnam, Republic of Korea; 2Department of Pulmonary and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
Correspondence: Ji-Hyun Lee
Department of Pulmonology, Allergy and Critical Care Medicine, CHA Bundang Medical Center, CHA University, 59 Yatap-ro, Bundang-gu, Seongnam 463-712, Republic of Korea
Tel +82 31 780 5205
Fax +82 31 780 2992
Purpose: We compared clinical characteristics of COPD patients according to symptom variability and evaluated the effect of symptom variability during the first year of enrollment on clinical outcomes of COPD.
Methods: We analyzed COPD patients’ data from the Korean Obstructive Lung Disease (KOLD) cohort. Symptom variability was defined based on the value of standard deviation (SD) of mMRC scores obtained every 3 months during the follow-up period of the first year. Patients were divided into 2 groups: the consistent (SD of mMRC scores =0) and variable (SD of mMRC scores >0) groups. Clinical characteristics and outcomes were compared in terms of symptom variability.
Results: A total of 407 patients were included in the analysis. Patient age was 67.2 years and 97.8% of the subjects were male. Initial mMRC was 1.5 and the SD of mMRC scores during the first year was 0.5. There were 137 subjects (33.7%) in the consistent group and 270 (66.3%) in the variable group. The variable group showed a lower FEV1 (P=0.019) and a higher mMRC score (P=0.001). The annual incidence of acute exacerbation of COPD (AE-COPD) tended to be higher in the variable group (P=0.078) and that of severe AE-COPD was higher in the variable group than in the consistent group (P=0.002). The variable group showed a higher proportion of annual exacerbators (P=0.001) and frequent exacerbators (P=0.017). In multivariate logistic regression analysis, the variable group was significantly associated with annual exacerbators (OR =1.963, P=0.011) and frequent exacerbators (OR =2.090, P=0.055).
Conclusion: COPD patients with symptom variability may have higher exacerbation risk as well as lower lung function and more severe respiratory symptoms.
Keywords: COPD, symptom, variability, exacerbation, death, lung function