WBR0418

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Author [[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Alison Leibowitz)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Biostatistics/Epidemiology
Sub Category SubCategory::Vascular
Prompt [[Prompt::The following table displays the results of a study investigating a new test for diagnosing aortic stiffness. What are the approximate sensitivity and specificity of the new test?

]]

Answer A [[AnswerA::Sensitivity = 83%

Specificity = 67%]]

Answer A Explanation [[AnswerAExp::Sensitivity (%) = TP/ (TP+FN) x 100 = 83%

Specificity (%) = TN/ (TN + FP) x 100 = 67%]]

Answer B [[AnswerB::Sensitivity = 83%

Specificity = 71%]]

Answer B Explanation AnswerBExp::71% represents the positive predictive value (PPV) of the test. PPV is calculated using the following equation: PPV = TP/ (TP+FP)
Answer C [[AnswerC::Sensitivity = 83%

Specificity = 83%]]

Answer C Explanation AnswerCExp::Both values represent the test's sensitivity.
Answer D [[AnswerD::Sensitivity = 67%

Specificity = 83%]]

Answer D Explanation AnswerDExp::The inverse is true.
Answer E [[AnswerE::Sensitivity = 67%

Specificity = 67%]]

Answer E Explanation AnswerEExp::Both values represent the test's specificity.
Right Answer RightAnswer::A
Explanation [[Explanation::Sensitivity (%) = TP/ (TP+FN) x 100 = 100/(100+20) x 100 = (100/120) x 100= 83%

Specificity (%) = TN/ (TN + FP) x 100 = 80/(80+40) x 100 = (80/120) x 100 = 67%


Educational Objective: Sensitivity (%) = TP/ (TP+FN) x 100 Specificity (%)= TN/ (TN + FP) x 100
References: First Aid 2014 page 51]]

Approved Approved::Yes
Keyword WBRKeyword::Specificity, WBRKeyword::Sensitivity, WBRKeyword::calculation, WBRKeyword::equation, WBRKeyword::study, WBRKeyword::aortic stiffness
Linked Question Linked::
Order in Linked Questions LinkedOrder::