title: The phenotype of concurrent chronic bronchitis and frequent exacerbations in patients with severe COPD attending Swedish secondary care units.
abstract: BACKGROUND
  Chronic bronchitis and previous exacerbations are both well-known risk factors for new exacerbations, impaired health-related quality of life, and increased mortality in COPD. The aim of the study was to characterize the phenotype of concurrent chronic bronchitis and frequent exacerbation in severe COPD.
  
  
  METHODS
  Information on patient characteristics, comorbidity, and exacerbations from the previous year (total number and number requiring hospitalization) was collected from 373 patients with stage III and IV COPD attending 27 secondary care respiratory units in Sweden. Logistic regression used chronic bronchitis and frequent exacerbations (≥2 exacerbations or ≥1 hospitalized exacerbations in the previous year) as response variables. Stratification and interaction analyses examined effect modification by sex.
  
  
  RESULTS
  Chronic bronchitis was associated with current smoking (adjusted odds ratio [OR] [95% CI], 2.75 [1.54-4.91]; P=0.001), frequent exacerbations (OR [95% CI], 1.93 [1.24-3.01]; P=0.004), and musculoskeletal symptoms (OR [95% CI], 1.74 [1.05-2.86]; P=0.031), while frequent exacerbations were associated with lung function (forced expiratory volume in 1 second as a percentage of predicted value [FEV1% pred]) (OR [95% CI] 0.96 [0.94-0.98]; P=0.001) and chronic bronchitis (OR [95% CI] 1.73 [1.11-2.68]; P=0.015). The phenotype with both chronic bronchitis and frequent exacerbations was associated with FEV1% pred (OR [95% CI] 0.95 [0.92-0.98]; P=0.002) and musculoskeletal symptoms (OR [95% CI] 2.55 [1.31-4.99]; P=0.006). The association of smoking with the phenotype of chronic bronchitis and exacerbations was stronger in women than in men (interaction, P=0.040).
  
  
  CONCLUSIONS
  Musculoskeletal symptoms and low lung function are associated with the phenotype of combined chronic bronchitis and frequent exacerbations in severe COPD. In women, current smoking is of specific importance for this phenotype. This should be considered in clinical COPD care.
authors.affiliation: Department of Respiratory Medicine, Örebro University, Örebro, Sweden.
authors.forename: Josefin
authors.initials: J
authors.lastname: Sundh
authors.affiliation: Department of Public Health and Caring Science, Family Medicine and Preventive Medicine, Uppsala University, Uppsala, Sweden.
authors.forename: Gunnar
authors.initials: G
authors.lastname: Johansson
authors.affiliation: Unit for Lung and Airway Research, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Kjell
authors.initials: K
authors.lastname: Larsson
authors.affiliation: Unit for Lung and Airway Research, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Lindén
authors.affiliation: Department of Respiratory Medicine and Allergology, Lund University, Lund, Sweden.
authors.forename: Claes-Göran
authors.initials: CG
authors.lastname: Löfdahl
authors.affiliation: Department of Public Health and Clinical Medicine, Division of Medicine/Respiratory Medicine, Umeå University, Umeå, Sweden.
authors.forename: Thomas
authors.initials: T
authors.lastname: Sandström
authors.affiliation: Department of Medical Sciences, Respiratory, Allergy and Sleep Research, Uppsala University, Uppsala, Sweden.
authors.forename: Christer
authors.initials: C
authors.lastname: Janson
mesh_terms: D000368:Aged; D029481:Bronchitis, Chronic / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*; D016009:Chi-Square Distribution; D015897:Comorbidity; D018450:Disease Progression; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D016015:Logistic Models; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009140:Musculoskeletal Diseases / Q000453:epidemiology / Q000503:physiopathology; D016017:Odds Ratio; D010641:Phenotype; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*; D012307:Risk Factors; D063728:Secondary Care Centers; D012720:Severity of Illness Index; D012737:Sex Factors; D012907:Smoking / Q000009:adverse effects / Q000453:epidemiology / Q000503:physiopathology; D013548:Sweden / Q000453:epidemiology; D013997:Time Factors
keywords: chronic obstructive lung disease; lung function; musculoskeletal symptoms; smoking