Denominator in sensitivity is ?
**Core Concept**
Sensitivity, also known as true positive rate, is a measure of a diagnostic test's ability to correctly identify those with a disease. It is calculated as the number of true positives (correctly identified patients with the disease) divided by the sum of true positives and false negatives (patients with the disease who are incorrectly identified as healthy).
**Why the Correct Answer is Right**
The correct answer is **True Positives**. Sensitivity is calculated as the ratio of true positives to the total number of actual cases (true positives + false negatives). This means that the denominator in the sensitivity calculation includes all patients with the disease, regardless of whether they were correctly or incorrectly diagnosed.
**Why Each Wrong Option is Incorrect**
* **Option A:** **False Positives** is incorrect because it refers to patients who do not have the disease but are incorrectly identified as having it. This is not part of the denominator in the sensitivity calculation.
* **Option B:** **True Negatives** is incorrect because it refers to patients who do not have the disease and are correctly identified as healthy. This is not part of the denominator in the sensitivity calculation.
* **Option C:** **False Negatives** is incorrect because it is already part of the denominator in the sensitivity calculation, not the numerator.
**Clinical Pearl / High-Yield Fact**
Remember that sensitivity is a measure of a test's ability to detect true positives, and it is calculated as the ratio of true positives to the total number of actual cases (true positives + false negatives).
**Correct Answer:** D. All patients with the disease (true positives + false negatives).