title: Healthcare-associated pneumonia does not accurately identify potentially resistant pathogens: a systematic review and meta-analysis.
abstract: BACKGROUND
  The 2005 American Thoracic Society/Infectious Diseases Society of America guidelines introduced a concept of healthcare-associated pneumonia (HCAP) to define patients at higher risk of antibiotic-resistant pathogens, thus requiring broad spectrum therapy. There has been no systematic evaluation of the ability of this definition to identify antibiotic-resistant pathogens.
  
  
  METHODS
  We conducted a systematic review and meta-analysis of studies comparing the frequency of resistant pathogens (defined as methicillin-resistant Staphylococcus aureus, Enterobacteriaceae, and Pseudomonas aeruginosa) in populations with HCAP compared with populations with community-acquired pneumonia (CAP). Predictive accuracy was evaluated using the area under the receiver operator characteristic curve (AUC). The frequencies of pathogens in each group were pooled using a random effects model.
  
  
  RESULTS
  Twenty-four studies were included (n = 22 456). Overall study quality was poor. HCAP was associated with an increased risk of methicillin-resistant S. aureus (odds ratio [OR], 4.72; 95% confidence interval [CI], 3.69-6.04) enterobactericeae (OR, 2.11; 95% CI, 1.69-2.63), and P. aeruginosa (OR, 2.75; 95% CI, 2.04-3.72; all P < .0001), but these analyses were confounded by publication bias. The discriminatory ability of HCAP for resistant pathogens was low (AUC, 0.70; 95% CI, 0.69-0.71) and was lower in high-quality (AUC, 0.66; 95% CI, 0.62-0.70) and prospective studies (AUC, 0.64; 95% CI 0.62-0.66). After adjustment for age and comorbidities, mortality was not increased in HCAP (OR, 1.20; 95% CI, 0.85-1.70; P = .30).
  
  
  CONCLUSIONS
  The HCAP concept is based on predominantly low-quality evidence and does not accurately identify resistant pathogens. Mortality in HCAP does not appear to be due to a higher frequency of resistant pathogens.
authors.affiliation: Tayside Respiratory Research Group, University of Dundee, Ninewells Hospital and Medical School, Dundee, Scotland, United Kingdom.
authors.forename: James D
authors.initials: JD
authors.lastname: Chalmers
authors.forename: Catriona
authors.initials: C
authors.lastname: Rother
authors.forename: Waleed
authors.initials: W
authors.lastname: Salih
authors.forename: Santiago
authors.initials: S
authors.lastname: Ewig
mesh_terms: D001419:Bacteria / Q000187:drug effects* / Q000302:isolation & purification*; D024881:Drug Resistance, Bacterial; D004755:Enterobacteriaceae / Q000187:drug effects* / Q000302:isolation & purification; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification; D053717:Pneumonia, Ventilator-Associated / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000302:isolation & purification
keywords: guidelines; healthcare-associated infection; meta-analysis; mortality; pneumonia