Users' Guide: Diagnostic Tests
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Are the results valid?
What are the results?
Will the results help me in patient care?
Understanding Likelihood Ratios
How much do LRs change disease likelihood?

Are the results valid?       

Was there an independent, blind comparison with a reference standard?

• Is reference standard used acceptable?
• Were both reference standard and test applied to all patients?

Did the patient sample include an appropriate spectrum of patients to whom the test will be applied?

Did the results of the test being evaluated influence the decision to perform the reference standard?

• " Verification " or "work-up" bias?

Were the test's methods described clearly enough to permit replication?

• Preparation of patient?
• Performance of test?
• Analysis and interpretation of results?

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What are the results?

What are the likelihood ratios for the test results?

• Are LR's for the test results presented or data necessary for their calculation provided?
• How big or small are the LR's?

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Will the results help me in patient care?

Will the test be reproducible and well interpreted in my practice setting?

Are the results applicable to my patients?

• Similar distribution of disease severity?
• Similar distribution of competing diseases?
• Compelling reasons why the results should not be applied?

Will the test results change my management?

• Test and treatment thresholds?
• High or low LR's?

Will my patients be better off because of the test?

• Is target disorder dangerous if left undiagnosed?
• Is test risk acceptable?
• Does effective treatment exist?
• Will information from test lead to change of management beneficial to patient?

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