WBR0793

Author	[[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Biostatistics/ Epidemiology
Sub Category	SubCategory::Reproductive
Prompt	[[Prompt::A new urine pregnancy test is being studied before being distributed to pharmacies. A trial is conducted to compare the results of this new test to a combination of imaging and blood human chorionic gonadotropin (HCG) levels to validate the pregnancy. A table showing the results of the study is shown below. What is the probability that a woman is really pregnant if her urine pregnancy test result comes back positive? ]]
Answer A	AnswerA::85.71%
Answer A Explanation	AnswerAExp::This refers to the sensitivity.
Answer B	AnswerB::75%
Answer B Explanation	AnswerBExp::This refers to the positive predictive value.
Answer C	AnswerC::89.28%
Answer C Explanation	AnswerCExp::This refers to the NPV.
Answer D	AnswerD::80.64%
Answer D Explanation	AnswerDExp::This refers to the specificity.
Answer E	AnswerE::62%
Answer E Explanation	AnswerEExp::This does not refer to any particular value.
Right Answer	RightAnswer::B
Explanation	[[Explanation::The positive predictive value is the probability that a person really has a condition if his test result is positive. The calculation is shown below. Educational Objective: Positive predictive value (PPV) = [True positive/(True positive+False positive)] Educational Objective: References: ]]
Approved	Approved::No
Keyword	WBRKeyword::Positive predictive value
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::