WBR0793
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| Author | [[PageAuthor::Serge Korjian M.D. (Reviewed by Serge Korjian)]] |
|---|---|
| Exam Type | USMLE Step 1 |
| Main Category | Biostatistics/Epidemiology |
| Sub Category | Reproductive |
| Prompt | [[Prompt::A new urine pregnancy test is being evaluated before marketing. 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 comparing the results of the study is shown below. What is the probability that a woman is truly pregnant if her urine pregnancy test is positive?
|
| Answer A | 85.71% |
| Answer A Explanation | This refers to the sensitivity. |
| Answer B | 75% |
| Answer B Explanation | This refers to the positive predictive value. |
| Answer C | 89.28% |
| Answer C Explanation | This refers to the NPV. |
| Answer D | 80.64% |
| Answer D Explanation | This refers to the specificity. |
| Answer E | 62% |
| Answer E Explanation | This does not refer to any particular value. |
| Right Answer | B |
| Explanation | [[Explanation::The positive predictive value is the probability that a person really has a condition if their test result is positive. The calculation is shown below.
|
| Approved | Yes |
| Keyword | Positive predictive value |
| Linked Question | |
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