<p>Diagnosis Worksheet Every clinician would like a diagnostic test that is 100% sensitive and 100% specific. However, in the real world this is never the case. Studies looking at a better diagnostic test must be carefully analyzed to avoid common pitfalls of population prevalence and pre-test probability.</p><p>Step 1: Why did they do this study? What question were they trying to answer?</p><p>Step 2: Define the Study Group</p><p>What were the inclusion criteria? What are the significance of these, if any?</p><p>What were the exclusion criteria? Was this appropriate?</p><p>Step 3: Making the Diagnosis Define the “reference test.” Is the comparison being made to the “Gold Standard?”</p><p>Were the study group subjected to both the “reference” test and the “standard” test? Was it blinded?</p><p>Step 4: Results What are the baseline characteristics of the study group? (usually Table 1.)</p><p>Are these similar to the patients you see?</p><p>Calculate Sensitivity, Specificity, Positive Predictive Value, Negative Predictive Value (use chart below)</p><p>Disease/Target Disorder Disease/Target Disorder Totals YES NO Test Positive A B A+B</p><p>Test Negative C D C+D Totals A+C B+D What is the sensitivity of the test? a/(a+c)</p><p>What is the specificity of the test? d/(b+d)</p><p>How does this compare to the comparison test?</p><p>What is the Positive Predictive Value? a/(a+b)</p><p>What is the Negative Predictive Value? d/(c+d)</p><p>Calculate Likelihood Ratio (+) LR+ = sensitivity/ (1-specificity)</p><p>Calculate Likelihood Ratio (-) LR(-) = (1-sensitivity)/specificity Step 6: Discussion Points/Questions</p><p>What are the advantages and disadvantages of this test compared to the Gold Standard?</p><p>Is the prevalence of the disease in our population similar to the study population?</p><p>Does this study look at pre-test probability? How does it compare to our population?</p><p>Is the test available to our patients? Is it affordable?</p><p>Was this test independently validated in another group of patients?</p><p>Most importantly, do you think this changes the morbidity or mortality of the disease we are trying to detect?</p><p>For further study, for those interested in research…</p><p>During the initial reading, imagine you are the researchers doing the study and see if you would approach it the same way. Then, after reviewing the article, do an after-action-review and see if you would do anything different knowing the results.</p>