WBR0418

Author	[[PageAuthor::Rim Halaby, M.D. [1] (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 in diagnosing aortic stiffness. Which of the following 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% corresponds to the positive predictive value (PPV). PPV is calculated by the following equation: PPV = TP/ (TP+FP)
Answer C	[[AnswerC::Sensitivity = 83% Specificity = 83%]]
Answer C Explanation	AnswerCExp::Both values correspond to 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 correspond to 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::