Differential changes in quality of life components over 5 years in chronic obstructive pulmonary disease patients
Received 15 November 2014
Accepted for publication 23 January 2015
Published 10 April 2015 Volume 2015:10(1) Pages 745—757
Checked for plagiarism Yes
Review by Single anonymous peer review
Peer reviewer comments 2
Editor who approved publication: Dr Richard Russell
Katsura Nagai,1 Hironi Makita,1 Masaru Suzuki,1 Kaoruko Shimizu,1 Satoshi Konno,1 Yoichi M Ito,2 Masaharu Nishimura1
On behalf of the Hokkaido COPD Cohort Study Investigators
1First Department of Medicine, Hokkaido University School of Medicine, 2Department of Biostatistics, Hokkaido University Graduate School of Medicine, Sapporo, Japan
Background: The aim of the study was to examine the longitudinal change in quality of life components of patients with chronic obstructive pulmonary disease (COPD).
Methods: In the Hokkaido COPD Cohort Study, 261 subjects were appropriately treated and followed over 5 years with a 74% follow-up rate at the end. The longitudinal changes in St George’s Respiratory Questionnaire (SGRQ) scores were annually evaluated with forced expiratory volume in 1 second (FEV1). The subjects were classified into the rapid decliners, slow decliners, and sustainers based on ∆FEV1/year.
Results: The activity component of SGRQ generally deteriorated over time, and its annual decline was the greatest in the rapid decliners (<25th percentile). In contrast, the symptom component improved significantly year by year in the sustainers (>75 percentile), and it did not deteriorate even in the rapid decliners. Of the baseline data, predictors for worsening of the activity component were older age and lower body mass index. Larger reversibility was related to symptom component improvement. Of the follow-up data, ∆FEV1/year was the best predictor for worsening of the components of SGRQ. Continuous smoking was another factor for worsening of the activity component. For the symptom component, a history of exacerbation by admission definition was the determinant of its deterioration, whereas use of beta agonists was related to improvement.
Conclusion: The longitudinal changes of quality of life and their determinants are markedly different and independent between its components. The activity component of SGRQ generally deteriorated over years, while the symptom component rather improved in some patients with COPD under appropriate treatment.
Keywords: annual change, forced expiratory volume in 1 second, SGRQ, smoking, exacerbation
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