title: Relationship between lung function impairment and health-related quality of life in COPD and interstitial lung disease.
abstract: BACKGROUND
  Health-related quality-of-life (HRQL) measures have been correlated with lung function in patients with COPD and interstitial lung disease (ILD). However, different pathophysiologic mechanisms may influence how these distinct diseases affect HRQL, resulting in differing HRQL by pulmonary diagnosis among patients with similar severity of ventilatory impairment.
  
  
  METHODS
  The National Heart, Lung, and Blood Institute Lung Tissue Research Consortium provided data on well-characterized participants with COPD (n = 576) and ILD (n = 405) at four clinical sites. Using multiple linear regression, we examined the effects of FEV₁ (% predicted) and diagnosis (ILD vs COPD) on HRQL scores, including total St. George Respiratory Questionnaire (SGRQ) scores and Short Form-12 (SF-12) physical component summary (PCS) and mental component summary (MCS) scores.
  
  
  RESULTS
  Participants with ILD had, on average, higher SGRQ scores (15.33 points; 95% CI, 12.46-18.19; P <.001) and lower SF-12 PCS scores (-4.73 points; 95% CI, -6.31 to -3.14; P <.001) compared with patients with COPD with similar FEV₁ % predicted values, indicating worse HRQL. The specific diagnosis also modified the effect of FEV₁ on the total SGRQ score (P = .003) and the SF-12 PCS score (P = .03). There was no relationship between lung function and SF-12 MCS scores.
  
  
  CONCLUSIONS
  HRQL scores were worse for patients with ILD compared with patients with COPD with similar degrees of ventilatory impairment. Differences in dyspnea mechanism or in the rate of disease progression may account for these differences in HRQL.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Cristine E
authors.initials: CE
authors.lastname: Berry
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: M Bradley
authors.initials: MB
authors.lastname: Drummond
authors.affiliation: Division of Pulmonary and Critical Care Medicine, University of Michigan Health System, Ann Arbor, MI.
authors.forename: MeiLan K
authors.initials: MK
authors.lastname: Han
authors.affiliation: C-TASC Clinical Trials and Surveys Corporation, Owings Mills, MD.
authors.forename: Daner
authors.initials: D
authors.lastname: Li
authors.affiliation: C-TASC Clinical Trials and Surveys Corporation, Owings Mills, MD.
authors.forename: Cathy
authors.initials: C
authors.lastname: Fuller
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Mayo Clinic College of Medicine, Rochester, MN.
authors.forename: Andrew H
authors.initials: AH
authors.lastname: Limper
authors.affiliation: Division of Pulmonary and Critical Care Medicine, University of Michigan Health System, Ann Arbor, MI.
authors.forename: Fernando J
authors.initials: FJ
authors.lastname: Martinez
authors.affiliation: Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado, Denver School of Medicine, Aurora, CO.
authors.forename: Marvin I
authors.initials: MI
authors.lastname: Schwarz
authors.affiliation: Division of Pulmonary and Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA.
authors.forename: Frank C
authors.initials: FC
authors.lastname: Sciurba
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD. Electronic address: rwise@jhmi.edu.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Wise
mesh_terms: D000368:Aged; D018450:Disease Progression; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D007361:Intelligence Tests; D016014:Linear Models; D008168:Lung / Q000503:physiopathology*; D017563:Lung Diseases, Interstitial / Q000503:physiopathology* / Q000523:psychology*; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology* / Q000523:psychology*; D011788:Quality of Life / Q000523:psychology*; D012129:Respiratory Function Tests; D012720:Severity of Illness Index