Evidence-based Medicine Toolkit

Appraising diagnosis articlesIs the studyvalid?Are the resultsimportant?1 Was there a clearly defined question?2 Was the presence or absence of thetarget disorder confirmed with a referencestandard?• Was this comparison independent fromand blind to the study test results?3 Was the test evaluated on an appropriatespectrum of patients?4 Was the reference standard applied to allpatients?Work out sensitivity, specificity and likelihoodratios (LRs):TestresultTarget disorderPresentPositive a bNegative c dAbsentSensitivity =aa + cSpecificity =bb + dLR+sensitivity=(positive result) (1 – specificity)LR–(1 – sensitivity)=(negative result) specificityCan the resultshelp you?Is there a SpPIN or SnNOUT?Can you generate a post-test probability foryour patient?See p. 73.34