title: Evaluation of the Winthrop-University Hospital criteria to identify Legionella pneumonia.
abstract: OBJECTIVE
  To measure the ability of a set of clinical parameters, the Winthrop-University Hospital (WUH) criteria, to identify Legionella pneumonia while discriminating against bacteremic pneumococcal pneumonia at the time of hospitalization for community-acquired pneumonia (CAP).
  
  
  METHODS
  Retrospective case-control study.
  
  
  METHODS
  An urban county hospital and a tertiary-care Veterans Affairs hospital.
  
  
  METHODS
  Thirty-seven patients with Legionella pneumonia (diagnosed by a positive result of a urinary Legionella antigen test) and 31 patients with bacteremic pneumococcal pneumonia. A subgroup of patients with all required laboratory criteria were studied further.
  
  
  RESULTS
  The WUH criteria correctly identified 29 of 37 patients with Legionella pneumonia (sensitivity, 78%; 95% confidence interval [CI], 61 to 90%), while successfully excluding legionellosis in 20 of 31 patients with bacteremic pneumococcal pneumonia (specificity, 65%; 95% CI, 45 to 80%). The positive and negative predictive values, adjusted for a relative prevalence of 1:3 between Legionella and Streptococcus pneumoniae bacteremia, were 42% (95% CI, 25 to 61%) and 90% (95% CI, 74 to 97%), respectively. In the subgroup analysis, the WUH criteria were successful in identifying 20 of 23 patients with Legionella pneumonia (sensitivity, 87%; 95% CI, 65 to 97%), while excluding legionellosis in 9 of 18 patients with bacteremic pneumococcal pneumonia (specificity, 50%; 95% CI, 27 to 73%). The adjusted positive and negative predictive values for a 1:3 relative prevalence were 37% (95% CI, 20 to 59%) and 92% (95% CI, 62 to 98%), respectively. The predictive values were changed in the directions expected for an increased relative prevalence of 1:1. The areas under the receiver operating characteristic curves were 0.72 +/- 0.06 for the entire study group and 0.68 +/- 0.09 for the subgroup.
  
  
  CONCLUSIONS
  Although the WUH criteria discriminated fairly well between cases (mean +/- SE) and control subjects, the sensitivity is not high enough to exclude legionellosis confidently. These results suggest that empiric therapy for Legionella pneumonia should be included in the initial antibiotic regimen for hospitalized patients with CAP.
authors.affiliation: Division of Infectious Diseases, Indiana University School of Medicine, Indianapolis, IN 46202, USA. sgupta1@iupui.edu
authors.forename: S K
authors.initials: SK
authors.lastname: Gupta
authors.forename: T F
authors.initials: TF
authors.lastname: Imperiale
authors.forename: G A
authors.initials: GA
authors.lastname: Sarosi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000907:Antibodies, Bacterial / Q000652:urine; D016470:Bacteremia / Q000175:diagnosis; D017714:Community-Acquired Infections / Q000175:diagnosis; D019091:Critical Pathways; D005260:Female; D006766:Hospitals, County; D006786:Hospitals, Urban; D006787:Hospitals, Veterans; D006801:Humans; D007196:Indiana; D007875:Legionella / Q000276:immunology; D007877:Legionnaires' Disease / Q000175:diagnosis* / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011018:Pneumonia, Pneumococcal / Q000175:diagnosis; D011237:Predictive Value of Tests
chemical_list: D000907:Antibodies, Bacterial