Faculty of Health and Medical Sciences

Appraise the evidence

Study type: Diagnosis

Learn more about:


Validity

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Clinical importance

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Applicability

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EBP calculations

  Gold standard positive
(condition present)
Gold standard negative
(condition not present)
Test positive True positive
A
False positive
B
Test negative False negative
C
True negative
D
Sensitivity = A / (A + C) Positive predictive value = A / (A + B)
Specificity = D / (B + D) Negative predictive value = D / (C + D)
  • Likelihood ratio for a positive test result = sens/(1-spec)
  • Likelihood ratio for a negative test result = (1-sens)/spec
  • Pre-test probability (prevalence) = (A+C)/(A+B+C+D)
  • Pre-test odds = prevalence/(1-prevalence)

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Diagnosis accuracy study worksheet:
Basic critical appraisal
Advanced critical appraisal