Admission chest radiograph lacks sensitivity in the diagnosis of community-acquired pneumonia

Am J Med Sci. 2009 Apr;337(4):236-40. doi: 10.1097/MAJ.0b013e31818ad805.


Introduction: : The clinical and epidemiological significance of community-acquired pneumonia (CAP) with a chest radiograph demonstrating no parenchymal infiltrate has not been studied. We determined the percentage of patients with a clinical diagnosis of CAP who did not have radiographic opacifications and compared this group with patients with CAP and radiographic infiltrates.

Methods: : Patients admitted with a diagnosis of CAP were identified. Clinical history, physical examination, laboratory studies, and microbiological cultures were reviewed in a random sample of 105 patients. Admission and subsequent chest radiographs were interpreted without knowledge of the clinical data.

Results: : Twenty-one percent (22/105) of patients with a clinical diagnosis of CAP had negative chest radiographs at presentation. Demographic, clinical, and laboratory data were the same in both groups. Fifty-five percent of patients with initially negative chest radiographs who had follow-up studies developed an infiltrate within 48 hours.

Conclusions: : In patients admitted with a clinical diagnosis of CAP, the initial chest radiograph lacks sensitivity and may not demonstrate parenchymal opacifications in 21% of patients. Moreover, greater than half of patients admitted with a negative chest radiograph will develop radiographic infiltrates within 48 hours. Further studies are needed to develop evidence-based criteria for the diagnosis of CAP.

MeSH terms

  • Community-Acquired Infections* / diagnosis
  • Community-Acquired Infections* / diagnostic imaging
  • Comorbidity
  • Humans
  • Male
  • Middle Aged
  • Pneumonia* / diagnosis
  • Pneumonia* / diagnostic imaging
  • Radiography, Thoracic / standards*
  • Retrospective Studies
  • Sensitivity and Specificity
  • Severity of Illness Index