title: The relevance of respiratory viral infections in the exacerbations of chronic obstructive pulmonary disease—a systematic review.
abstract: BACKGROUND
  Despite the increasing knowledge on the role of viruses in exacerbations of COPD (AECOPD), it is less clear which viruses are involved and to what extent they contribute to exacerbations. This review aims to systematically combine and evaluate the available literature of the prevalence of respiratory viruses in patients with AECOPD, detected by PCR.
  
  
  METHODS
  An electronic search strategy was performed on PubMed and Embase and reference lists were screened for eligible studies. Cross-sectional, prospective studies and case-control studies were included. The primary outcome measure was the prevalence of respiratory viruses (adenovirus, bocavirus, coronavirus, EBV, hMPV, influenza, parainfluenza, rhino-/enterovirus, RSV) in respiratory secretions of patients during an AECOPD. Secondary outcomes were the odds of the presence of the viruses in different respiratory secretions and the odds of the presence of viruses in upper and lower respiratory tract (URT/LRT) samples.
  
  
  RESULTS
  Nineteen studies with 1728 patients were included. Rhino-/enteroviruses (16.39%), RSV (9.90%) and influenza (7.83%) were the most prevalent viruses detected with lower detection rates of coronaviruses (4.08%) and parainfluenza (3.35%). Adenovirus (2.07%), hMPV (2.78%) and bocaviruses (0.56%) appear to be rare causative agents of AECOPD. Definitive conclusions regarding the role of EBV cannot be made. Seven of the eight analyzed viruses had a higher prevalence in LRT samples. Coronaviruses were detected more frequently in the URT.
  
  
  CONCLUSIONS
  Respiratory viruses are frequently detected in both URT and LRT samples in AECOPD with rhino-/enteroviruses, RSV and influenza viruses the most prevalent viruses. Detection rates vary between the two sites for different viruses.
authors: Department of Respiratory Medicine, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors: W A R
authors: WA
authors: Zwaans
authors: Department of Respiratory Medicine, Imperial College London, London, United Kingdom.
authors: P
authors: P
authors: Mallia
authors: Department of Respiratory Medicine, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors: M E C
authors: ME
authors: van Winden
authors: Department of Respiratory Medicine, Maastricht University Medical Centre, Maastricht, The Netherlands. Electronic address: g.rohde@mumc.nl.
authors: G G U
authors: GG
authors: Rohde
mesh_terms: D012634:Bodily Secretions / Q000821:virology; D006801:Humans; D016133:Polymerase Chain Reaction; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000473:pathology* / Q000821:virology*; D012137:Respiratory System / Q000821:virology; D012141:Respiratory Tract Infections / Q000150:complications* / Q000453:epidemiology / Q000821:virology*; D014777:Virus Diseases / Q000150:complications* / Q000453:epidemiology / Q000821:virology*; D014780:Viruses / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*
keywords: Exacerbation; Polymerase chain reaction; Pulmonary disease, chronic obstructive; Systematic review; Viruses