title: Cardiovascular comorbidity in COPD: systematic literature review.
abstract: BACKGROUND
  Cardiovascular disease (CVD) is common among patients with COPD. However, it is not clear whether this is due to shared risk factors or if COPD increases the risk for CVD independently. This study aimed to provide a systematic review of studies that investigated the association between COPD and CVD outcomes, assessing any effect of confounding by common risk factors.
  
  
  METHODS
  A search was conducted in MEDLINE (via PubMed) for observational studies published between January 1990 and March 2012 reporting cardiovascular comorbidity in patients with COPD (or vice versa).
  
  
  RESULTS
  Of the 7,322 citations identified, 25 studies were relevant for this systematic review. Twenty-two studies provided an estimate for CVD risk in COPD, whereas four studies provided estimates of COPD risk in CVD. The crude prevalence for the aggregate CVD category ranged from 28% to 70%, likely due to differences in populations studied and CVD definitions; unadjusted rate ratio (RR) estimates of unspecified CVD among patients with COPD compared with patients without COPD ranged from 2.1 to 5.0. The association between COPD and CVD persisted after adjustment for shared risk factors in the majority of the studies. Two studies found a relationship between the severity of airflow limitation and CVD risk. Increased RRs were observed for individual CVD types, but their estimates varied considerably for congestive heart failure, coronary heart disease, arrhythmias, stroke, arterial hypertension, and peripheral arterial disease.
  
  
  CONCLUSIONS
  Available observational data support the hypothesis that COPD is associated with an increased risk of CVD.
authors.affiliation: Worldwide Epidemiology, GlaxoSmithKline R&D, Uxbridge, England. Electronic address: hana.x.muellerova@gsk.com.
authors.forename: Hana
authors.initials: H
authors.lastname: Müllerova
authors.affiliation: Thorax Institute, Hospital Clinic, IDIBAPS, Universitat de Barcelona and FISIB, CIBER Enfermedades Respiratorias (CIBERES), Mallorca, Spain.
authors.forename: Alvar
authors.initials: A
authors.lastname: Agusti
authors.affiliation: Weill Cornell Medical College, New York, NY.
authors.forename: Sebhat
authors.initials: S
authors.lastname: Erqou
authors.affiliation: Lovelace Clinic Foundation, Albuquerque, NM.
authors.forename: Douglas W
authors.initials: DW
authors.lastname: Mapel
mesh_terms: D002318:Cardiovascular Diseases / Q000209:etiology*; D006801:Humans; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications*; D012307:Risk Factors