title: Clinical factors associated with negative urinary antigen tests implemented for the diagnosis of community-acquired pneumococcal pneumonia in adult patients.
abstract: OBJECTIVE
  This study investigated clinical factors associated with negative urinary antigen tests (UAT) implemented for the diagnosis of pneumococcal community-acquired pneumonia (CAP) in adult patients.
  
  
  METHODS
  We reviewed the medical records of 755 adult patients who completed the UAT in our hospital between 2009 and 2012. Of these, we evaluated 63 patients with bacteriologically confirmed definite pneumococcal CAP (33 were UAT-positive, and 30 were UAT-negative).
  
  
  RESULTS
  There was no significant difference between the UAT-positive and the UAT-negative patients regarding age, dehydration, respiratory failure, orientation, blood pressure (ADROP) score (the CAP severity score proposed by the Japanese Respiratory Society), gender, white blood cell counts, liver/kidney function tests, or urinalysis. However, serum C-reactive protein (CRP) concentrations were 31% lower in the UAT-negative patients than in the UAT-positive patients (p = 0.02). Furthermore, the prothrombin time-international normalized ratio was 50% higher in the UAT-negative patients than in the UAT-positive patients, although the difference did not reach statistical significance (p = 0.06). The prevalence of comorbidities was similar in both UAT-positive and UAT-negative patients. However, warfarin had been prescribed in 8 (27%) of the UAT-negative patients compared to only 1 (3%) of the UAT-positive patients (odds ratio = 11.6; p = 0.01).
  
  
  CONCLUSIONS
  These results suggested that low serum CRP concentrations and the use of warfarin increased the possibility with which false-negative UAT results occurred in these patients with pneumococcal CAP.
authors.affiliation: Department of Respiratory Medicine and Infection Control, Tokyo Medical University Ibaraki Medical Center, Inashiki, Japan.
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Watanabe
authors.forename: Tomonori
authors.initials: T
authors.lastname: Uruma
authors.forename: Gen
authors.initials: G
authors.lastname: Tazaki
authors.forename: Ryota
authors.initials: R
authors.lastname: Kikuchi
authors.forename: Takao
authors.initials: T
authors.lastname: Tsuji
authors.forename: Masayuki
authors.initials: M
authors.lastname: Itoh
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000652:urine; D000942:Antigens, Bacterial / Q000652:urine*; D002097:C-Reactive Protein / Q000032:analysis; D017714:Community-Acquired Infections; D015897:Comorbidity; D005260:Female; D006784:Hospitals, Teaching; D006801:Humans; D008297:Male; D008875:Middle Aged; D011018:Pneumonia, Pneumococcal / Q000652:urine*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013296:Streptococcus pneumoniae; D014041:Tokyo; D014859:Warfarin / Q000652:urine
chemical_list: D000925:Anticoagulants; D000942:Antigens, Bacterial; D014859:Warfarin; D002097:C-Reactive Protein