Community-acquired pneumonia: history and examination does not usefully diagnose it

Clinical bottom line (level 1a)

  1. No individual sign or symptom can diagnose or exclude community-acquired pneumonia.
  2. Few patients suspected of having community-acquired pneumonia have it.
  3. Physicians are not very good at diagnosing or excluding pneumonia.
  4. Patients are more likely to have pneumonia if they have
    • aegophony (LR: infinity)
    • bronchial breathing (LR+3.5)
    • dementia (LR+3.4)
    • respiratory rate > 30 (LR+2.6)
    • decreased breath sounds (LR+2.3)
    • dullness to percussion (LR+2.2)
    • history of immunosuppression (LR+2.2)
  5. Patients are less likely to have pneumonia if they have
    • a history of asthma (LR-0.10)
    • no abnormal vital signs (LR-0.18)
    • no cough (LR-0.31)
Metlay et al: Journal of the American Medical Association 1997; 278 (17): 1440-1445
Expires March 2003

The study

Systematic review of all diagnostic studies of
  • Patients: with suspected community-acquired pneumonia
  • Intervention: clinical examination
  • Outcome: community-acquired pneumonia


    • Articles found in English using MEDline, 1966 to 1995 (search terms: available on request )

    Selection criteria: as above
    Appraisal criteria: detailed in text: independent blinded reference standard in a prospective cohort of at least 50 patients
    Articles excluded if:
    • hospital-acquired pneumonia, paediatric pneumonia, or AIDS-related pneumonia
    • aged < 16
    • case series (<10 observations) or review articles without original data



    The evidence


    diagnostic test LR+
    (95% CI)    		 post-test probability LR-
    (95% CI)    		 post-test probability
    cough 1.8
    ( to )     		9% 0.31
    ( to )     		2%
    dyspnea 1.4
    ( to )     		7% 0.67
    ( to )     		3%
    sputum production 1.3
    ( to )     		6% 0.55
    ( to )     		3%
    fever 2.1
    (1.4 to 2.9)     		10% 0.59
    ( to )     		3%
    night sweats 1.7
    ( to )     		8% 0.83
    ( to )     		4%
    chills 1.3
    ( to )     		6% 0.72
    ( to )     		4%
    myalgias 1.3
    ( to )     		6% 0.58
    ( to )     		3%
    sore throat 0.78
    ( to )     		4% 1.6
    ( to )     		8%
    rhinorrhea 0.78
    ( to )     		4% 2.4
    ( to )     		11%
    history of dementia 3.4
    ( to )     		15% 0.94
    ( to )     		5%
    history of immunosuppression 2.2
    ( to )     		10% 0.85
    ( to )     		4%
    history of asthma 0.10
    ( to )     		0.5% 3.8
    ( to )     		17%
    respiratory rate > 30 2.6
    ( to )     		12% 0.80
    ( to )     		4%
    respiratory rate > 20 1.2
    ( to )     		6% 0.66
    ( to )     		3%
    heart rate >100 1.6
    ( to )     		8% 0.73
    ( to )     		4%
    asymmetric respiration -
    (3.2 to infinity)     		100% 0.96
    ( to )     		5%
    dullness to percussion 2.2
    ( to )     		10% 0.79
    ( to )     		4%
    decreased breath sounds 2.3
    ( to )     		11% 0.78
    ( to )     		4%
    crackles 1.6
    ( to )     		8% 0.83
    ( to )     		4%
    rhonchi 1.4
    ( to )     		7% 0.76
    ( to )     		4%
    bronchial breath sounds 3.5
    ( to )     		16% 0.90
    ( to )     		5%
    temperature > 37.8 C 1.4
    ( to )     		7% 0.63
    ( to )     		3%
    any of respiratory rate > 30, heart rate > 100, temperature > 37.8 C 1.2
    ( to )     		6% 0.18
    (0.07 to 0.46)     		0.9%
    aegophony 2.0
    ( to )     		10% 0.96
    ( to )     		5%
    any chest finding 1.3
    ( to )     		6% 0.57
    (0.39 to 0.83)     		3%
    physician's prediction of pneumonia 2.0
    (1.5 to 2.4)     		10% 0.25
    (0.09 to 0.61)     		1%
    total

    • Prevalence of pneumonia ranged from 2.6% to 38% - post-test probabilities calculated from a pretest probability of 5%.
    • Physicians agree poorly about chest signs
      • dullness to percussion: K 0.52
      • wheeze on ausculatation K 0.51
      • crackles K 0.41
      • reduced chest movement K 0.38
      • bronchial breath sounds K 0.32
      • tachypnoea K 0.25
      • whispering pectoriloquy K 0.11
      • increased tactile fremitus K 0.01

    Comments

    1. By limiting the search to English only, relevant material may have been missed.
    2. Even in the primary care setting, it is difficult to rule out pneumonia on linical signs

    Citation

    1. Metlay JP, Kapoor WN, Fine MJ, et al: does this patient have community-acquired pneumonia? Diagnosing pneumonia by history and physical examination. Journal of the American Medical Association 1997; 278 (17): 1440-1445
    Search Terms:
    Contributor: Chris Ball and Clare Wotton, November 1999
    Reviewer: Mitsuhiro Kamei

    Clinical Question.
    Patient suspected community-acquired pneumonia
    Intervention or Exposure clinical findings
    Outcome community-acquired pneumonia