Validation of the American Thoracic Society-Infectious Diseases Society of America Guidelines for Hospital-Acquired Pneumonia in the Intensive Care Unit

Background. The 2005 guidelines of the American Thoracic Society-Infectious Diseases Society of America Guidelines for Hospital for managing hospital-acquired pneumonia classified patients according to time of onset and risk factors for potentially drug-resistant microorganisms to select the empirical antimicrobial treatment. We assessed the microbial prediction and validated the adequacy of these guidelines for antibiotic strategy. Methods. We prospectively observed 276 patients with intensive care unit-acquired pneumonia. We classified patients into group 1 (early onset without risk factors for potentially drug-resistant microorganisms; 38 patients) and group 2 (late onset or risk factors for potentially drug-resistant microorganisms; 238 patients). We determined the accuracy of guidelines to predict causative microorganisms and the influence of guidelines adherence in patients' outcome. Results. Microbial prediction was lower in group 1 than in group 2 (12 [50%] of 24 vs 119 [92%] of 129; P < .001) mainly because of potentially drug-resistant microorganisms in 10 patients (26%) from group 1. Guideline adherence was higher in group 2 (153 [64%] vs 7 [18%]; P < .001). Guideline adherence resulted in more treatment adequacy than did nonadherence (69 [83%] vs 45 [64%]; P = .013) and a trend toward better response to empirical treatment in group 2 only but did not influence mortality. Reclassifying patients according to the risk factors for potentially drug-resistant microorganisms of the former 1996 American Thoracic Society guidelines increased microbial prediction in group 1 to 21 (88%; P = .014); all except 1 patient with potentially drug-resistant microorganisms were correctly identified by these guidelines. Conclusions. The 2005 guidelines predict potentially drug-resistant microorganisms worse than the 1996 guidelines. Adherence to guidelines resulted in more adequate treatment and a trend to a better clinical response in group 2, but it did not influence mortality.