Table 2 Diagnostic performance of ETA using quantitative culture obtained from standardised BAL as the reference, with growth at >104 CFU/ml defining “true VAP”
Sensitivity (%)Specificity (%)PPV (%)NPV (%)+LR–LR
Qualitative ETA cultures9014218510.6
Quantitative ETA cultures725530881.60.5
  • Qualitative ETA is growth of any organism; quantitative ETA is growth of any organism at >106 colony-forming units (CFU)/ml.20 A likelihood ratio is a likelihood that a person with a positive (or negative) test has the disease in question; further detail can be found in Strauss et al.25

  • BAL, bronchoalveolar lavage; ETA, endotracheal aspirate; NPV, negative predictive value; PPV, positive predictive value; +LR, positive likelihood ratio; –LR, negative likelihood ratio; VAP, ventilator-associated pneumonia.