title: Clinical Features according to the Frequency of Acute Exacerbation in COPD.
abstract: BACKGROUND
  Chronic obstructive pulmonary disease (COPD) is now regarded as a heterogenous disease, with variable phenotypes. Acute exacerbation of COPD is a major event that alters the natural course of disease. The frequency of COPD exacerbation is variable among patients. We analyzed clinical features, according to the frequency of acute exacerbation in COPD.
  
  
  METHODS
  Sixty patients, who visited Gyeongsang National University Hospital from March 2010 to October 2010, were enrolled. Patients were divided into two groups, according to their frequency of acute exacerbation. Frequent exacerbator is defined as the patient who has two or more exacerbation per one year. We reviewed patients' medical records and investigated modified Medical Research Council (MMRC) dyspnea scale, smoking history and frequency of acute exacerbation. We also conducted pulmonary function test and 6-minute walking test, calculated body mass index, degree of airway obstruction and dyspnea and exercise capacity (BODE) index and measured CD146 cells in the peripheral blood.
  
  
  RESULTS
  The number of frequent exacerbators and infrequent exacerbators was 20 and 40, respectively. The frequent exacerbator group had more severe airway obstruction (forced expiratory volume in one second [FEV(1)], 45% vs. 65.3%, p=0.001; FEV(1)/forced vital capacity, 44.3% vs. 50.5%, p=0.046). MMRC dyspnea scale and BODE index were significantly higher in the frequent exacerbator group (1.8 vs. 1.1, p=0.016; 3.9 vs. 2.1, p=0.014, respectively). The fraction of CD146 cells significantly increased in the frequent exacerbator group (2.0 vs. 1.0, p<0.001).
  
  
  CONCLUSIONS
  Frequent exacerbator had more severe airway obstruction and higher symptom score and BODE index. However, circulating endothelial cells measured by CD146 needed to be confirmed in the future.
authors.affiliation: Division of Respiratory and Critical Care Medicine, Department of Internal Medicine, Gyeongsang National University School of Medicine, Jinju, Korea.
authors.forename: Seung Jun
authors.initials: SJ
authors.lastname: Lee
authors.forename: Seung Hun
authors.initials: SH
authors.lastname: Lee
authors.forename: Yu Eun
authors.initials: YE
authors.lastname: Kim
authors.forename: Yu Ji
authors.initials: YJ
authors.lastname: Cho
authors.forename: Yi Yeong
authors.initials: YY
authors.lastname: Jeong
authors.forename: Ho Cheol
authors.initials: HC
authors.lastname: Kim
authors.forename: Jin Hyun
authors.initials: JH
authors.lastname: Kim
authors.forename: Jin Jong
authors.initials: JJ
authors.lastname: You
authors.forename: Chul-Ho
authors.initials: CH
authors.lastname: Yoon
authors.forename: Jong Deog
authors.initials: JD
authors.lastname: Lee
authors.forename: Young Sil
authors.initials: YS
authors.lastname: Hwang