Pneumonia: diarrhoea and an elevated CK made Legionella more likely

Clinical bottom line (level 4)

  1. Legionella infection was relatively common in patients attending an emergency department with pneumonia.
  2. Legionella was more likely with diarrhoea (LR+5.8) or an elevated CK (LR+5.8) , and less likely if an underlying disease was present (LR-0.22) .
Sopena et al: Chest 1998; 113: 1195-1200
Expires March 2003

The study

Setting: emergency department, university hospital, Spain

173 patients (aged , 74% male) from 392 patients attending with pneumonia (acute symptoms and a new infiltrate on chest X-ray taken within 24 hours of admission)

Excluded if
  • low probability for Legionalla infection or no cause found
  • aged < 14
  • discharged from hospital within 10 days of onset of symptoms
  • suspicion of bronchoaspiration, obstructive pneumonia or pulmonary tuberculosis



    • Independent ?blinded reference standard, applied in some patients from a consecutive appropriate spectrum.
    Reference standard:
    • Legionella detected by
      • isolation from respiratory sample
      • fourfold increase in antibiotic titres
      • antigen found in r
    Diagnostic test: clinical features on admission
    • A multivariate logistic regression analysis was performedto identify features that independently predicted Legionella pneumonia.

    The evidence

    pre-test probability of Legionella pneumonia: 12%, (95% CI: 9.0% to 16%)

    diagnostic test Legionella other organism LR
    (95% CI)    		 post-test probability
    underlying disease 0.22
    (0.069 to 0.72)     		3%
    diarrhoea 5.8
    (1.5 to 22)     		44%
    CK > 232 U/l 5.8
    (1.5 to 22)     		44%
    total

    • No other clinical features were independently associatedwith Legionella pneumonia.

    Comments

    1. Failure to include patients with an uncertain cause makes these test results appear better than in reality.
    2. Nature of criteria for exclusion from analysis unclear, further complicating interpretation

    Citation

    1. Sopena N, Sabria-Leal M, Pedro-Botet ML, et al: comparative study of the clinical presentation of Legionella pneumonia and other community-acquired pneumonias. Chest 1998; 113: 1195-1200
    Search Terms: ?
    Contributor: Chris Ball and Clare Wotton, December 1999
    Reviewer: Guy De Bruin

    Clinical Question.
    Patient pneumonia
    Intervention or Exposure clinical features
    Outcome Legionella infection