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Three Part Question

In [adult patients presenting to the Emergency Department with suspected community acquired pneumonia] is [auscultation] reliable in [confirming the diagnosis]?

Clinical Scenario

A 50 year-old lady presents with a fever and cough. Physical examination of her chest reveals crackles in the left base. You wonder whether this means that you can be confident of a diagnosis of pneumonia before the results of further investigations are obtained.

Search Strategy

Medline 1966 to 2007 February Week 1 using OVID interface
Embase 1980 - 2007 Week 7 using OVID interface
[exp Pneumonia, Bacterial/ OR exp Pneumonia/ OR pneumonia.mp.] AND [exp Auscultation OR auscultat$.mp.] limit to humans and English language

Search Outcome

110 papers were identified in Medline and 192 in Embase. Five were relevant to the three-part question.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Wipf, J. E. et al 1999 USA	54 patients with respiratory symptoms (cough and change in sputum) who presented to the Emergency Department.	Prospective, blinded diagnostic study Chest exam performed by 2 (of 3) physicians (blinded to patient vital signs and history). Chest radiograph read by radiologist used as gold standard.	Sensitivity of overall clinical diagnosis	Range 47% to 69%	1. Small patient group. 2. Group characteristics: Entirely male, all late-middle aged, many with underlying respiratory/cardiac pathology. 3. Long study period affecting standardisation between patients. 4. Chest radiograph used as gold standard which can be insensitive and nonspecific.
			Specificity of overall clinical diagnosis	58% to 75%
			Multivariate analysis of rales (crackles) in presence of pneumonia	Odds Ratio 3.73
			Interrobserver reliability for clinical diagnosis of pneumonia	Paired kappa ranged from 0.18 to 0.32, indicating only fair agreement
Leuppi, J.D. et al 2005 Switzerland	243 consecutive patients attending the Emergency Department with chest symptoms.	Prospective, double blinded study Diagnosis proposed before and after auscultation by a physician (with initial access to referring letter and patient history) and compared with the (seperate) diagnosis made on discharge letter.	Contribution of lung auscultation	Unchanged diagnosis after auscultation in 96.4% of cases	1.Chest symptoms were not described for initial recruitment. 2.Auscultatory findings were not described. 3.Influence of patient's history to the diagnosis proposed would contribute to findings despite attempts to control this. The study was not specific for pneumonia and so a cardiac history (eg chest pain with orthopnea) with crackles will give a very different impression to sputum with crackles.
			Predictive value of normal lung auscultation for absence of lung or heart disease	Odds Ratio 0.12 (95%CI 0.053-0.29)
Hopstaken et al Netherlands	246 adult patients presenting to 25 GP's with symptoms and signs consistent with lower respiratory tract infection (LRTI). Signs and symptoms recorded by GP on standard form; PA and lateral chest radiographs blindly interpreted by radiologist on day 3 formed the gold standard.	Prospective diagnostic cohort study	Auscultation abnormality for diagnosis of pneumonia	Present in 84% of patients; Odds ratio 2.0 (95% CI 0.6 - 6.9). PPV 14.2%; NPV 92.3%	Interobserver reliability not assessed. No sample size calculation. Wide confidence intervals suggest the study may be underpowered.
			Accuracy of crackles for diagnosis of pneumonia	Present in 20.6% of patients; Odds ratio 1.5 (0.7-3.7); PPV 18.0%; NPV 87.6%
Osmer and Cole 1966 United States	200 'random' cases of young men admitted to hospital with radiographic evidence of acute pneumonia between September 1963 and August 1964. Auscultatory findings recorded by "internists skilled in chest diseases" compared to chest radiograph results, as reported by three radiologists.	Retrospective diagnostic cohort	Absence of auscultatory findings	Occurred in 50 (25%) of cases.	Retrospective analysis. No sample size calculation. "Random" method for identification of cases not described. No mention of blinding. Only cases of pneumonia included (not an undifferentiated group).
			Absence of rales	Occurred in 98 (49%) of cases.
			Auscultatory abnormality in same location as chest radiograph abnormality	Occurred in 52 (26%) of cases.
Metlay et al 1997 United States	Published studies of patients suspected of having pneumonia, which evaluated clinical signs for diagnostic accuracy (identified in Medline). Gold standard was chest radiography. All studies were reviewed for quality.	Systematic review	Interobserver reliability of chest signs	Kappa scores: Crackles 0.41; Wheezes 0.51; Bronchial breath sounds 0.32. (Indicates only fair-moderate agreement for each).	Only Medline was searched. No attempts to retrieve unpublished data. No attempt to meta-analyse the data. Confidence intervals not always stated. Exact P values not stated.
			Any chest finding for diagnosis of pneumonia	LR+ 1.3, LR- 0.57 (95% CI 0.39-0.83). (P<0.05). This is insufficient to safely confirm or exclude pneumonia in practice.
			Crackles for diagnosis of pneumonia	LR+ ranged from 1.6-2.7; LR- 0.78-0.87. (P<0.05)
			Bronchial breath sounds for diagnosis of pneumonia	LR+ 3.5; LR- 0.90. (P<0.05)
			Rhonchi for diagnosis of pneumonia	LR+ ranged from 'not significant' - 1.5; LR- 'not significant' - 0.76

Comment(s)

The stethoscope remains a hallmark of the physician's diagnostic armoury. However, the studies identified report it's limited diagnstic efficacy for acute pneumonia. Further, the studies reported high rates of interobserver variability. Other conditions, including the kind of stethoscope used, the conditions it is used in (noisy resuscitation room vs quiet cubicle) and the experience of the examiner, are likely to influence sensitivity and specificity. The studies identified suggest that auscultation has a limited role in the diagnosis of actue pneumonia in Emergency Department. Of course, this does not mean that the stethoscope should be thrown away. A careful physical examination may guide the Emergency physician in the formulation of differential diagnoses and selection of appropriate investigations.

Editor Comment

Abbreviations: PPV: Positive predictive value; NPV: Negative predictive value; LR+: Positive likelihood ratio; LR-: Negative likelihood ratio; CI: Confidence intervals.

Clinical Bottom Line

In the Emergency Department, pneumonia cannot reliably be confirmed or excluded by auscultation, or indeed physical examination, alone.

References

1. Wipf, J.E; Lipsky, B.A; Hirschmann, J.V; Boyko, E.D; Takasugi, J; Peugeot, R.L; Davis, C.L. Diagnosing Pneumonia by Physical Examination. Relevant or Relic? Archives of Internal Medicine 1999;159:1082-1087
2. Leuppi, J.D; Dieterle, T; Koch, G; Martina, B; Tamm, M; Perruchoud, A.P; Wildeisen, I; Leimenstoll, B.M. Diagnostic value of lung auscultation in the emergency room setting Swiss Medical Weekly 2005;135:520-524
3. Hopstaken RM; Muris JWM; Knottnerus JA; Kester ADM; Rinkens PELM; Dinant GJ Contributions of symptoms, signs, erythrocyte sedimentation rate, and C-reactive protein to a diagnosis of pneumonia in acute lower respiratory tract infection British Journal of General Practice 2003; 53: 358-364
4. Osmer JC; Cole BK. The stethoscope and roentgenogram in acute pneumonia Southern Medical Journal 1966; 1: 75-77
5. Metlay JP; Kapoor WN; Fine MJ. The rational clinical examination: Does this patient have community-acquired pneumonia? Diagnosing pneumonia by history and physical examination JAMA 1997; 278(17): 1440-1445