title: Comorbid Influences on Generic Health-Related Quality of Life in COPD: A Systematic Review.
abstract: BACKGROUND
  Chronic obstructive pulmonary disease (COPD) is a leading cause of mortality and of loss of disability-adjusted life years worldwide. It often is accompanied by the presence of comorbidity.
  
  
  OBJECTIVE
  To systematically review the influence of COPD comorbidity on generic health-related quality of life (HRQoL).
  
  
  METHODS
  A systematic review approach was used to search the databases Pubmed, Embase and Cochrane Library for studies evaluating the influence of comorbidity on HRQoL in COPD. Identified studies were analyzed according to study characteristics, generic HRQoL measurement instrument, COPD severity and comorbid HRQoL impact. Studies using only non-generic instruments were excluded.
  
  
  RESULTS
  25 studies met the selection criteria. Seven studies utilized the EQ-5D, six studies each used the SF-36 or SF-12. The remaining studies used one of six other instruments each. Utilities were calculated by four EQ-5D studies and one 15D study. Patient populations covered both early and advanced stages of COPD and ranged from populations with mostly stage 1 and 2 to studies with patients classified mainly stage 3 and 4. Evidence was mainly created for cardiovascular disease, depression and anxiety as well as diabetes but also for quantitative comorbid associations. Strong evidence is pointing towards the significant negative association of depression and anxiety on reduced HRQoL in COPD patients. While all studies found the occurrence of specific comorbidities to decrease HRQoL in COPD patients, the orders of magnitude diverged. Due to different patient populations, different measurement tools and different concomitant diseases the study heterogeneity was high.
  
  
  CONCLUSIONS
  Facilitating multimorbid intervention guidance, instead of applying a parsimony based single disease paradigm, should constitute an important goal for improving HRQoL of COPD patients in research and in clinical practice.
authors.affiliation: Institute of Health Economics and Health Care Management, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Comprehensive Pneumology Center Munich (CPC-M), Member of the German Center for Lung Research (DZL), Neuherberg, Germany.
authors.forename: Manuel B
authors.initials: MB
authors.lastname: Huber
authors.affiliation: Institute of Health Economics and Health Care Management, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Comprehensive Pneumology Center Munich (CPC-M), Member of the German Center for Lung Research (DZL), Neuherberg, Germany.
authors.forename: Margarethe E
authors.initials: ME
authors.lastname: Wacker
authors.affiliation: Department of Medicine, Pulmonary and Critical Care Medicine, Philipps-Universität Marburg, University Medical Centre Giessen and Marburg (UGMLC), Member of the German Center for Lung Research (DZL), Marburg, Germany.
authors.forename: Claus F
authors.initials: CF
authors.lastname: Vogelmeier
authors.affiliation: Institute of Health Economics and Health Care Management, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Comprehensive Pneumology Center Munich (CPC-M), Member of the German Center for Lung Research (DZL), Neuherberg, Germany; Munich Center of Health Sciences, Ludwig-Maximilians-Universität, Munich, Germany.
authors.forename: Reiner
authors.initials: R
authors.lastname: Leidl
mesh_terms: D006801:Humans; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000503:physiopathology*; D011788:Quality of Life