title: Limited value of chest radiography in predicting aetiology of lower respiratory tract infection in general practice.
abstract: BACKGROUND
  In patients with lower respiratory tract infection (LRTI), changes on chest radiography are rare but poorly characterised, especially in general practice.
  
  
  OBJECTIVE
  To describe the range of findings on chest radiographs and the associations between these findings and the aetiology of LRTI.
  
  
  METHODS
  A prospective observational study.
  
  
  METHODS
  General practices in the Leiden region, The Netherlands.
  
  
  METHODS
  Adult patients with a defined LRTI were included. Standard medical history and physical examination were performed. Sputum, blood, and throat swabs were collected for diagnostic tests. Chest X-ray findings were assessed in relation to the aetiology.
  
  
  RESULTS
  An abnormality on the chest X-ray was observed in 72 (55%) patients. Forty-five patients (35%) had changes due to infection, and 26 (20%) due to pneumonia. Pathogens were detected in 84 patients (33 single bacterial, 43 single viral, and 8 dual). Twelve (29%) patients with a bacterial infection (including dual infections) compared to four (9%) patients with viral infection had pneumonia on the chest X-ray (odds ratio [OR] = 4.0; 95% confidence interval [CI] = 1.2 to 13.8). Using the presence of pneumonia on chest X-ray as a test to predict a bacterial infection, the positive predictive value and the negative predictive value were 75% (CI = 48 to 93%) and 57% (CI = 45 to 69%), respectively.
  
  
  CONCLUSIONS
  Pneumonia on the chest X-ray was found more frequently in patients with a bacterial infection than in patients with a viral infection. However, the sensitivity and the specificity are such that pneumonia on the chest X-ray is not a reliable test to discriminate between bacterial and non-bacterial LRTI in the general practice setting.
authors.affiliation: Department of Public Health and Primary Care, Leiden University Medical Centre, Leiden, The Netherlands. a.w.graffelman@lumc.nl
authors.forename: A Willy
authors.initials: AW
authors.lastname: Graffelman
authors.forename: Francois E J A
authors.initials: FE
authors.lastname: Willemssen
authors.forename: Harmine M
authors.initials: HM
authors.lastname: Zonderland
authors.forename: Arie Knuistingh
authors.initials: AK
authors.lastname: Neven
authors.forename: Aloys C M
authors.initials: AC
authors.lastname: Kroes
authors.forename: Peterhans J
authors.initials: PJ
authors.lastname: van den Broek
mesh_terms: D000293:Adolescent; D000328:Adult; D005194:Family Practice; D006193:Haemophilus influenzae / Q000302:isolation & purification; D006801:Humans; D008487:Medical History Taking; D009177:Mycoplasma pneumoniae / Q000302:isolation & purification; D009426:Netherlands; D010808:Physical Examination; D018410:Pneumonia, Bacterial / Q000000981:diagnostic imaging*; D011024:Pneumonia, Viral / Q000000981:diagnostic imaging*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011859:Radiography; D012680:Sensitivity and Specificity