title: Emphysematous phenotype is an independent predictor for frequent exacerbation of COPD.
abstract: METHODS
  Frequent exacerbation is an important phenotype in chronic obstructive pulmonary disease (COPD), while emphysema is associated with many comorbidities and lung function decline.
  
  
  OBJECTIVE
  To investigate unique features of frequent exacerbators and test the hypothesis that emphysematous phenotype is associated with frequent exacerbations of COPD.
  
  
  METHODS
  A total of 380 COPD patients were recruited from 16 hospitals in Korea from June 2005 to April 2012 for analysis. We searched for independent predictors of frequent exacerbators in comparison with non-exacerbators.
  
  
  RESULTS
  As the severity of emphysema increased, forced expiratory volume in 1 s (FEV₁), and FEV₁/FVC (forced volume capacity) worsened; hyperinflationary features characterised by higher total lung capacity (TLC) were observed (P < 0.05). Frequent exacerbators had lower body mass index (BMI), higher St George's Respiratory Questionnaire (SGRQ) scores, higher residual volume (RV)/TLC, more severe airflow limitation (lower FEV₁ and FEV₁/FVC), lower carbon monoxide diffusion capacity, lower serum protein levels and a higher emphysema index than non-exacerbators (P < 0.05). In multivariate analysis, frequent exacerbators were independently associated with a higher emphysema index, lower serum protein levels and higher RV/TLC (P < 0.05).
  
  
  CONCLUSIONS
  Our data show that the severity of emphysema, severe static hyperinflation and serum lower protein levels are independent predictors of frequent exacerbations in COPD patients.
authors.affiliation: Department of Pulmonary and Critical Care Medicine and Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Y-M
authors.initials: YM
authors.lastname: Oh
authors.affiliation: Department of Pulmonary and Critical Care Medicine, Ajou University School of Medicine, Suwon, Korea.
authors.forename: S-S
authors.initials: SS
authors.lastname: Sheen
authors.affiliation: Department of Pulmonary and Critical Care Medicine, Ajou University School of Medicine, Suwon, Korea.
authors.forename: J H
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department of Pulmonary and Critical Care Medicine, Ajou University School of Medicine, Suwon, Korea.
authors.forename: U R
authors.initials: UR
authors.lastname: Jin
authors.affiliation: Department of Pulmonary and Critical Care Medicine and Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: J-W
authors.initials: JW
authors.lastname: Yoo
authors.affiliation: Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: J B
authors.initials: JB
authors.lastname: Seo
authors.affiliation: Department of Internal Medicine, Konkuk University School of Medicine, Seoul, Korea.
authors.forename: K H
authors.initials: KH
authors.lastname: Yoo
authors.affiliation: Department of Internal Medicine, CHA Bundang Medical Center, CHA University, Seongnam, Korea.
authors.forename: J-H
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Division of Pulmonology, Department of Internal Medicine, Hanyang University Guri Hospital, Hanyang University College of Medicine, Guri, Korea.
authors.forename: T-H
authors.initials: TH
authors.lastname: Kim
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: S Y
authors.initials: SY
authors.lastname: Lim
authors.affiliation: Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.
authors.forename: H I
authors.initials: HI
authors.lastname: Yoon
authors.affiliation: Department of Pulmonary and Critical Care Medicine and Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: J S
authors.initials: JS
authors.lastname: Lee
authors.affiliation: Department of Pulmonary and Critical Care Medicine and Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: S-D
authors.initials: SD
authors.lastname: Lee
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D001798:Blood Proteins / Q000032:analysis; D016009:Chi-Square Distribution; D015897:Comorbidity; D018450:Disease Progression; D015536:Down-Regulation; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D016015:Logistic Models; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D010641:Phenotype; D011237:Predictive Value of Tests; D011379:Prognosis; D011653:Pulmonary Diffusing Capacity; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D011656:Pulmonary Emphysema / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D056910:Republic of Korea / Q000453:epidemiology; D012307:Risk Factors; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D013997:Time Factors; D014109:Total Lung Capacity; D014797:Vital Capacity
chemical_list: D015415:Biomarkers; D001798:Blood Proteins