WBR0418
Jump to navigation
Jump to search
| Author | [[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Alison Leibowitz)]] |
|---|---|
| Exam Type | USMLE Step 1 |
| Main Category | Biostatistics/Epidemiology |
| Sub Category | 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 | Sensitivity = 83%
Specificity = 67% |
| Answer A Explanation | Sensitivity (%) = TP/ (TP+FN) x 100 = 83%
Specificity (%) = TN/ (TN + FP) x 100 = 67% |
| Answer B | Sensitivity = 83%
Specificity = 80% |
| Answer B Explanation | Sensitivity is correct. However, 80% represents the negative predictive value (NPV) of the test. NPV is calculated using the following equation: NPV = TN/ (TN+FN) |
| Answer C | Sensitivity = 71%
Specificity = 80% |
| Answer C Explanation | 71% represents the positive predictive value (PPV) of the test. PPV is calculated using the following equation: PPV = TP/ (TP+FP). 80% represents the negative predictive value (NPV) of the test. NPV is calculated using the following equation: NPV = TN/ (TN+FN) |
| Answer D | Sensitivity = 80%
Specificity = 71% |
| Answer D Explanation | 71% represents the positive predictive value (PPV) of the test. PPV is calculated using the following equation: PPV = TP/ (TP+FP). 80% represents the negative predictive value (NPV) of the test. NPV is calculated using the following equation: NPV = TN/ (TN+FN) |
| Answer E | Sensitivity = 71%
Specificity = 67% |
| Answer E Explanation | 71% represents the positive predictive value (PPV) of the test. PPV is calculated using the following equation: PPV = TP/ (TP+FP). On the other hand, specificity is correct. |
| Right Answer | 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%
|
| Approved | Yes |
| Keyword | Specificity, Sensitivity, Calculation, Equation, Aortic stiffness |
| Linked Question | |
| Order in Linked Questions |
