title: Clinical characteristics of patients with chronic obstructive pulmonary disease with comorbid bronchiectasis: a systemic review and meta-analysis.
abstract: BACKGROUND
  In the 2014 Global initiative for chronic Obstructive Lung Disease guidelines, bronchiectasis was for the first time defined as a comorbidity of chronic obstructive pulmonary disease (COPD), and this change has been retained in the 2015 update, which emphasizes the influence of bronchiectasis in the natural history of COPD. The present meta-analysis was aimed at summarizing the impact of bronchiectasis on patients with COPD.
  
  
  METHODS
  Databases including Embase, PubMed, and the Cochrane Central Register of Controlled Trials were searched comprehensively to identify all relevant human clinical studies published until August 2014. Bronchiectasis was confirmed either by computed tomography or high-resolution computed tomography. One or more clinicopathological or demographical characteristics, including age, sex, smoking history, daily sputum production, exacerbations, inflammatory biomarkers, lung function, and colonization by potentially pathogenic microorganisms (PPMs), were compared between COPD patients with and without bronchiectasis.
  
  
  RESULTS
  Six observational studies with 881 patients were included in the meta-analysis. The mean prevalence of bronchiectasis in patients with COPD was 54.3%, ranging from 25.6% to 69%. Coexistence of bronchiectasis and COPD occurred more often in male patients with longer smoking history. Patients with COPD and comorbid bronchiectasis had greater daily sputum production, more frequent exacerbation, poorer lung function, higher level of inflammatory biomarkers, more chronic colonization by PPMs, and higher rate of Pseudomonas aeruginosa isolation.
  
  
  CONCLUSIONS
  In spite of the heterogeneity between included studies and detectable publication bias, this meta-analysis demonstrated the impact of bronchiectasis in patients with COPD in all directions, indicating that coexistence of bronchiectasis should be considered a pathological phenotype of COPD, which may have a predictive value.
authors.affiliation: Department of Pulmonary Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China.
authors.forename: Yingmeng
authors.initials: Y
authors.lastname: Ni
authors.affiliation: Department of Pulmonary Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China.
authors.forename: Guochao
authors.initials: G
authors.lastname: Shi
authors.affiliation: Department of Pulmonary Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China.
authors.forename: Youchao
authors.initials: Y
authors.lastname: Yu
authors.affiliation: Department of Pulmonary Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China.
authors.forename: Jimin
authors.initials: J
authors.lastname: Hao
authors.affiliation: Department of Pulmonary Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China.
authors.forename: Tiantian
authors.initials: T
authors.lastname: Chen
authors.affiliation: Department of Pulmonary Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China.
authors.forename: Huihui
authors.initials: H
authors.lastname: Song
mesh_terms: D001987:Bronchiectasis / Q000175:diagnosis* / Q000453:epidemiology / Q000276:immunology / Q000382:microbiology / Q000503:physiopathology; D016009:Chi-Square Distribution; D015897:Comorbidity; D005260:Female; D006801:Humans; D018836:Inflammation Mediators / Q000276:immunology; D008168:Lung / Q000276:immunology / Q000382:microbiology / Q000503:physiopathology*; D008297:Male; D016017:Odds Ratio; D010641:Phenotype; D011237:Predictive Value of Tests; D015995:Prevalence; D011379:Prognosis; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000453:epidemiology / Q000276:immunology / Q000382:microbiology / Q000503:physiopathology; D012129:Respiratory Function Tests; D012307:Risk Factors; D012737:Sex Factors; D012907:Smoking / Q000009:adverse effects / Q000453:epidemiology; D013183:Sputum / Q000276:immunology / Q000382:microbiology; D014057:Tomography, X-Ray Computed
chemical_list: D018836:Inflammation Mediators
keywords: bronchiectasis; chronic obstructive pulmonary disease; meta-analysis; phenotype