INI-CET 2017 — Community Medicine

Q: A new test in red line has been designed to diagnose a disease condition. The test is applied to both normal and diseased population, the graph of which is given below. Which of the following is correct regarding the test?

Low sensitivity and low specificity. ***Low sensitivity and low specificity*** - In the provided graph, the **red line** curve (new test) for the healthy and diseased populations shows substantial **overlap**, meaning there is poor discrimination between the two groups. - A test with **low sensitivity** will miss many true positive cases (diseased individuals), and a test with **low specificity** will incorrectly identify many healthy individuals as diseased, both of which are indicated by the extensive overlap. *High sensitivity and high specificity* - This would be represented by two curves that are **well-separated**, with minimal overlap, allowing for clear distinction between healthy and diseased individuals. - Such a test would correctly identify most diseased individuals (**high sensitivity**) and most healthy individuals (**high specificity**). *High sensitivity and low specificity* - This would typically show a test that correctly identifies most diseased individuals (high true positive rate), but also incorrectly flags many healthy individuals as diseased (high false positive rate). - Graphically, this might appear as the diseased curve being mostly captured, but with significant spillover into the healthy range. *Low sensitivity and high specificity* - This scenario suggests a test that rarely misidentifies healthy individuals as diseased (low false positive rate), but also misses many diseased individuals (high false negative rate). - The healthy curve would be well-defined and distinct, but the diseased curve would significantly overlap with the healthy curve, indicating poor detection of disease. [Practice more Community Medicine PYQs on OnCourse]

Q: Which of the following vials can be used? (AIIMS Nov 2017)

1,2 can be used. ***1,2 can be used*** - Vials 1 and 2 show the **inner square lighter than or equal in color to the outer circle** on the VVM, indicating the vaccine has been stored correctly and is safe to use. - The **Vaccine Vial Monitor (VVM)** is a time-temperature indicator that changes color irreversibly when exposed to excessive heat. - These vials are at **VVM Stage 1 or 2** (usable stages), confirming they have not been exposed to heat that would degrade vaccine potency. *3,4 can be used* - This is **INCORRECT** because both vials 3 and 4 show VVM indicators that have reached **discard point**. - Vial 3's VVM shows the **inner square darker than the outer circle**, indicating heat exposure (VVM Stage 3 or beyond). - Vial 4's VVM shows an even **darker inner square, nearly merged with the outer circle**, signifying severe heat damage. - **WHO/EPI guidelines** mandate discarding vaccines when VVM inner square becomes darker than outer circle. *1,2,3 can be used* - This is **INCORRECT** because vial 3 has crossed the **VVM discard point**. - The inner square in vial 3 is **darker than the outer circle**, indicating heat exposure that compromises vaccine efficacy. - Using heat-damaged vaccines leads to **immunization failure** and false sense of protection. *Only 1 can be used* - This is **INCORRECT** because vial 2 also shows a **safe VVM status** (inner square lighter than outer circle). - Both vials 1 and 2 are at usable VVM stages and can be administered safely. - There is **no visual difference** between the VVM status of vials 1 and 2 that would justify discarding vial 2. [Practice more Community Medicine PYQs on OnCourse]

2 Previous Year Questions with Answers & Explanations

Questions

A new test in red line has been designed to diagnose a disease condition. The test is applied to both normal and diseased population, the graph of which is given below. Which of the following is correct regarding the test?

Which of the following vials can be used? (AIIMS Nov 2017)

INI-CET 2017 - Community Medicine INI-CET Practice Questions and MCQs

Question 1: A new test in red line has been designed to diagnose a disease condition. The test is applied to both normal and diseased population, the graph of which is given below. Which of the following is correct regarding the test?

A. High sensitivity and high specificity
B. High sensitivity and low specificity
C. Low sensitivity and low specificity (Correct Answer)
D. Low sensitivity and high specificity

Explanation: ***Low sensitivity and low specificity*** - In the provided graph, the **red line** curve (new test) for the healthy and diseased populations shows substantial **overlap**, meaning there is poor discrimination between the two groups. - A test with **low sensitivity** will miss many true positive cases (diseased individuals), and a test with **low specificity** will incorrectly identify many healthy individuals as diseased, both of which are indicated by the extensive overlap. *High sensitivity and high specificity* - This would be represented by two curves that are **well-separated**, with minimal overlap, allowing for clear distinction between healthy and diseased individuals. - Such a test would correctly identify most diseased individuals (**high sensitivity**) and most healthy individuals (**high specificity**). *High sensitivity and low specificity* - This would typically show a test that correctly identifies most diseased individuals (high true positive rate), but also incorrectly flags many healthy individuals as diseased (high false positive rate). - Graphically, this might appear as the diseased curve being mostly captured, but with significant spillover into the healthy range. *Low sensitivity and high specificity* - This scenario suggests a test that rarely misidentifies healthy individuals as diseased (low false positive rate), but also misses many diseased individuals (high false negative rate). - The healthy curve would be well-defined and distinct, but the diseased curve would significantly overlap with the healthy curve, indicating poor detection of disease.

Question 2: Which of the following vials can be used? (AIIMS Nov 2017)

A. 1,2 can be used (Correct Answer)
B. 3,4 can be used
C. 1,2,3 can be used
D. Only 1 can be used

Explanation: ***1,2 can be used*** - Vials 1 and 2 show the **inner square lighter than or equal in color to the outer circle** on the VVM, indicating the vaccine has been stored correctly and is safe to use. - The **Vaccine Vial Monitor (VVM)** is a time-temperature indicator that changes color irreversibly when exposed to excessive heat. - These vials are at **VVM Stage 1 or 2** (usable stages), confirming they have not been exposed to heat that would degrade vaccine potency. *3,4 can be used* - This is **INCORRECT** because both vials 3 and 4 show VVM indicators that have reached **discard point**. - Vial 3's VVM shows the **inner square darker than the outer circle**, indicating heat exposure (VVM Stage 3 or beyond). - Vial 4's VVM shows an even **darker inner square, nearly merged with the outer circle**, signifying severe heat damage. - **WHO/EPI guidelines** mandate discarding vaccines when VVM inner square becomes darker than outer circle. *1,2,3 can be used* - This is **INCORRECT** because vial 3 has crossed the **VVM discard point**. - The inner square in vial 3 is **darker than the outer circle**, indicating heat exposure that compromises vaccine efficacy. - Using heat-damaged vaccines leads to **immunization failure** and false sense of protection. *Only 1 can be used* - This is **INCORRECT** because vial 2 also shows a **safe VVM status** (inner square lighter than outer circle). - Both vials 1 and 2 are at usable VVM stages and can be administered safely. - There is **no visual difference** between the VVM status of vials 1 and 2 that would justify discarding vial 2.