Table 2

Levels of evidence according to criteria from Centre for Evidence Based Medicine, Oxford

Group*TestContext (for diagnosis unless stated otherwise)Best evidence found
ASerum angiotensin converting enzymeSarcoidosis2b
ASerum antineutrophil cytoplasm antibody titreChurg Strauss disease4
ABronchial washingsTuberculosis1c
ABronchial washingsTo exclude tuberculosis4
ABronchoscopyLung cancer (abnormal chest x ray)1c
ABronchoscopyLung cancer (haemoptysis)1c
ABronchial biopsyLung cancer1b
ABronchial brush for cytologyLung cancer1b
ASerial chest x raysTo exclude lung cancer if stableNone
AComputed tomography bone densitometryCorticosteroid induced osteoporosis4
AElectrocardiogramTo explore a cardiac cause of breathlessness1b
AEosinophil countTo help diagnose asthma4
AErythrocyte sedimentation rateTo help diagnose tuberculosisNone
AExercise stress testIschaemic heart disease1a
AExercise oximetryPresence of lung diseaseNone
AFlow volume loopUpper airway obstruction4
AFine needle aspiration of lung mass (transcutaneous)Lung cancer1b
AHeaf testTuberculosis4
AHigh resolution computed tomographyInterstitial lung disease3
AHigh resolution computed tomographyBronchiectasis1b
ASerum immunoglobulin E concentrationTo help diagnose asthmaNone
AOvernight pulse oximetrySleep apnoea syndrome1b
APeak flow chartAsthma1b
APleural fluid protein concentrationTo differentiate exudate/transudate1a
AVentilation-perfusion scanPulmonary embolus1b
AVenogramDeep venous thrombosis4
BSerum angiotensin converting enzyme concentrationTo follow activity of sarcoidosisNone
BPeak flow chartAsthma: to step down treatment if low variabilityNone
BOral corticosteroid trialAsthma: to define best possible lung functionNone
BPeak flow chartCOPD: to treat with inhaled steroid if variableNone
BComputed tomography scan of thoraxLung cancer: to assess operability1a
CTrial of inhaled corticosteroidCOPD
CTrial of oral corticosteroidCOPD
CTrial of inhaled β agonistCOPDNone
CTrial of oral theophyllineCOPDNone
CTrial of inhaled long acting β agonistCOPDNone
CTrial of nasal corticosteroidCoughNone
CTrial of oral proton pump inhibitorCoughNone
  • * A = tests used to make or exclude diagnosis; B = tests used to assess prediagnosed condition; C = trials of therapy used explicitly to predict future response in individual patient.

  • †“None” indicates no studies found of test in this context.

  • ‡Studies that were found did not support use of trials of therapy to predict future response