NEET-PG 2015 - Community Medicine Practice Questions

Q: Which study design is most effective for investigating rare adverse effects of a drug?

Case-control study. ***Case-control study*** - This design starts by identifying individuals with the **rare adverse effect (cases)** and a control group without the effect to look back for exposure to the drug. - It is efficient for studying rare outcomes because it doesn't require following a large population for a long time to observe few events. *Cohort study* - A **cohort study** follows a group of individuals exposed and unexposed to a drug forward in time to observe outcomes. - While good for common outcomes, it would require an **extremely large sample size** and a long follow-up period to observe rare adverse drug effects. *Cross-sectional study* - A **cross-sectional study** assesses exposure and outcome simultaneously at a single point in time. - This design is suitable for determining **prevalence** but cannot establish temporal relationships between drug exposure and rare adverse effects, nor is it efficient for rare outcomes. *Clinical trial/experimental study* - **Clinical trials** are primarily designed to test the efficacy and safety of new interventions, usually focusing on common adverse effects. - They are generally **not powered** or long enough to detect rare adverse events, as such events would occur in very few participants, if any.

Q: Bladder cancer can occur in those who are working in dye industry for 25 years. Which study design is most appropriate for establishing a causal relationship between dye industry work and bladder cancer?

Cohort study. ***Cohort study*** - A **cohort study** tracks a group of individuals exposed to a risk factor (dye industry work) and a group not exposed over time to see who develops the outcome (bladder cancer). - This design allows for the calculation of **incidence rates** and relative risk, which are crucial for establishing a causal link, especially when the exposure is rare or specific. - Cohort studies establish **temporal relationship** (exposure precedes disease) and can demonstrate a **dose-response relationship**, both essential for proving causality. *Cross-sectional study* - A **cross-sectional study** assesses exposure and outcome simultaneously at a single point in time, making it difficult to determine the temporal sequence of events. - While it can identify associations, it cannot definitively establish a **cause-and-effect relationship** because it doesn't observe outcomes developing over time. *Case-control study* - A **case-control study** compares individuals with the outcome (cases) to individuals without the outcome (controls) and retrospectively looks for differences in past exposures. - While useful for studying **rare diseases** and can suggest associations, it is prone to **recall bias** regarding exposure history and cannot establish causality as definitively as cohort studies. *Randomized control trial* - A **randomized controlled trial (RCT)** involves randomly assigning participants to an intervention group or a control group and following them prospectively. - While RCTs provide the strongest evidence for causality, it would be **unethical** to intentionally expose people to a known carcinogen like dye industry chemicals for research purposes.

Q: Most commonly used blinding technique in epidemiological studies?

Double blinding. ***Double blinding*** - In **double blinding**, neither the **participants** nor the **researchers** administering the intervention and collecting data know who is in the treatment group versus the control group. - This method is widely used to prevent **observer bias** from the researchers and **participant bias** (e.g., placebo effect) from the subjects, thereby strengthening the study's internal validity. *Single blinding* - In **single blinding**, only the **participants** are unaware of their assignment to either the treatment or control group. - While it helps reduce participant bias, the **researchers' knowledge** of group assignments can still introduce **observer bias**, making it less rigorous than double blinding. *Triple blinding* - **Triple blinding** extends double blinding by ensuring that the **data analysts** are also unaware of the participant group assignments. - This technique further minimizes bias in the **interpretation and analysis of results**, but it is less commonly implemented due to its complexity and increased logistical challenges compared to double blinding. *None of the options* - This option is incorrect because **blinding techniques** are fundamental tools in epidemiological studies and clinical trials to ensure the objectivity and reliability of research findings. - **Blinding** helps eliminate conscious and unconscious biases that could otherwise influence study outcomes.

Q: Immunity starts after how many days of yellow fever vaccination ?

7-10 days. ***Correct: 7-10 days*** - The **onset of immunity** after yellow fever vaccination typically occurs within **7-10 days** for most individuals. - This period is crucial for the body to develop a protective immune response, which is why travelers are advised to get vaccinated at least **10 days before potential exposure** as per WHO guidelines. - Approximately **95% of vaccinees** develop protective immunity by day 10. *Incorrect: 2-3 weeks* - While immunity continues to strengthen over this period, **initial protective immunity** is established earlier, typically by 7-10 days. - This option represents a slightly delayed timetable for the initial establishment of immunity. *Incorrect: 4-5 weeks* - This duration is significantly longer than the time required for the initial protective immunity to develop after yellow fever vaccination. - At this point, robust and **long-lasting immunity** would generally be established, but it's not when immunity "starts." *Incorrect: 2-3 months* - This timeframe is far too long for the *start* of immunity following yellow fever vaccination. - By this point, immunity is not only well-established but also **lifelong** (the vaccine provides protection for life after a single dose).

Q: Droplet nuclei is a type of ?

Indirect transmission of pathogens. ***Indirect transmission of pathogens*** - **Droplet nuclei** are tiny airborne particles remaining after the evaporation of respiratory droplets, suspended in the air for prolonged periods, allowing pathogens to travel over longer distances. - This mode of transmission is considered **indirect** because it involves an environmental medium (air) rather than direct contact between individuals. *Vertical transmission of pathogens* - This refers to the transmission of a pathogen from a **mother to her offspring**, either during pregnancy, childbirth, or breastfeeding. - Examples include HIV and rubella, which are transmitted directly from parent to child, unlike airborne droplet nuclei. *Direct transmission of infectious agents* - This involves immediate physical contact or exposure between an infected individual and a susceptible host (e.g., touching, kissing, sexual contact). - It does not involve an intermediate environmental vehicle such as airborne particles that travel through the air from their source. *Biological transmission of pathogens* - This type of transmission involves an **arthropod vector** that not only transmits the pathogen but also allows it to multiply or develop within its body before transmission. - Examples include malaria transmitted by mosquitoes or Lyme disease by ticks, which is distinct from airborne droplet nuclei transmission.

Q: Which of the following is an example of indirect transmission by a living vector?

Transmission by mosquito. ***Transmission by mosquito*** - This is the classic example of **vector-borne transmission**, where a living biological vector (the mosquito) acts as an intermediary to transmit the infectious agent from an infected host to a susceptible one. - The disease-causing microorganism does not pass directly from person to person but is carried and transmitted by the living vector. - Examples include malaria, dengue, and filariasis. *Vertical transmission* - This refers to transmission of disease from a **mother to her child** during pregnancy, childbirth, or breastfeeding. - This is a form of **direct transmission** where the pathogen passes directly between biologically related individuals without an intermediate living vector. *Soil contact* - This represents **vehicle-borne transmission** where soil acts as a non-living vehicle (fomite) carrying pathogens. - While this is technically indirect transmission, it does not involve a **living biological vector** as specified in the question. - Examples include tetanus, hookworm, and ascariasis transmitted through contaminated soil. *Droplet infection* - This is a form of **direct transmission** where infectious droplets are expelled from the respiratory tract of an infected person and directly contact the mucous membranes of a susceptible person. - The droplets travel a short distance in close proximity, representing direct person-to-person transfer without any intermediate vector.

Q: What is a key benefit of Randomized Controlled Trials (RCTs) in clinical research?

They minimize selection bias.. ***They minimize selection bias.*** - **Randomization** in RCTs ensures that participants have an equal chance of being assigned to any of the treatment groups, thereby balancing potential **confounding factors** across groups. - This balance helps to ensure that any observed differences in outcomes between groups are more likely due to the intervention being studied rather than pre-existing differences among participants, thus minimizing **selection bias**. *They can be conducted more quickly than other study types.* - RCTs often require **extensive planning**, recruitment, and follow-up periods, making them one of the **most time-consuming** study designs. - The need for sufficient **power** to detect meaningful differences often translates into longer study durations. *They are ideal for studying rare diseases.* - Due to the requirement for **large sample sizes** to demonstrate statistical significance, RCTs are **not practical** for diseases with low prevalence. - Recruiting enough participants with a rare disease for an RCT can be extremely challenging and often **unfeasible**. *They are generally less expensive than other study types.* - RCTs are typically among the **most expensive** study designs because they involve extensive participant recruitment, intervention administration, data collection, and long-term follow-up. - The costs associated with staff, resources, and monitoring for ethical compliance contribute to their **high financial burden**.

Q: What is the range of values for the Physical Quality of Life Index (PQLI)?

0 to 100. ***0 to 100*** - The **Physical Quality of Life Index (PQLI)** is an index that measures the quality of life or well-being of a country, with values ranging from **0 (worst)** to **100 (best)**. - This standardized range allows for easy comparison of living standards and societal progress across different nations. *0 to 10* - This range is too small and does not accurately represent the comprehensive scoring system used for the **PQLI**, which aggregates multiple indicators. - While some individual metrics might use a 0-10 scale, the composite PQLI itself uses a broader range. *0 to 50* - This range is insufficient to capture the full spectrum of development indicators factored into the **PQLI**. - A maximum value of 50 would compress the data too much, making fine distinctions between countries less apparent. *100 to 200* - The **PQLI** is capped at 100, which signifies the highest possible quality of life; therefore, values above 100 are not possible. - This range suggests an overly optimistic or unstandardized index, which is not the case for PQLI.

Question 1

Which study design is most effective for investigating rare adverse effects of a drug?

Accepted Answer

Case-control study

Answer

Cohort study

Answer

Cross-sectional study

Answer

Clinical trial/experimental study

Question 2

Bladder cancer can occur in those who are working in dye industry for 25 years. Which study design is most appropriate for establishing a causal relationship between dye industry work and bladder cancer?

Accepted Answer

Cohort study

Answer

Cross-sectional study

Answer

Case-control study

Answer

Randomized control trial

Question 3

Most commonly used blinding technique in epidemiological studies?

Accepted Answer

Double blinding

Answer

None of the options

Answer

Single blinding

Answer

Triple blinding

Question 4

Immunity starts after how many days of yellow fever vaccination ?

Accepted Answer

7-10 days

Answer

2-3 weeks

Answer

4-5 weeks

Answer

2-3 months

Question 5

Which Diphtheria vaccine is recommended for a 14-year-old girl?

Accepted Answer

Tdap vaccine (Tetanus, Diphtheria, Pertussis)

Answer

DT vaccine (Diphtheria, Tetanus)

Answer

No suitable vaccine

Answer

DPT vaccine (Diphtheria, Pertussis, Tetanus)

Question 6

Droplet nuclei is a type of ?

Accepted Answer

Indirect transmission of pathogens

Answer

Direct transmission of infectious agents

Answer

Vertical transmission of pathogens

Answer

Biological transmission of pathogens

Question 7

Which of the following is an example of indirect transmission by a living vector?

Accepted Answer

Transmission by mosquito

Answer

Vertical transmission

Answer

Soil contact

Answer

Droplet infection

Question 8

Multiphasic screening means-

Accepted Answer

Application of two or more screening tests in combination at one time

Answer

Application of two or more screening tests in combination at different geographical areas

Answer

Application of separate screening tests for different diseases

Answer

Application of two or more screening tests in combination at different times

Question 9

What is a key benefit of Randomized Controlled Trials (RCTs) in clinical research?

Accepted Answer

They minimize selection bias.

Answer

They can be conducted more quickly than other study types.

Answer

They are ideal for studying rare diseases.

Answer

They are generally less expensive than other study types.

Question 10

What is the range of values for the Physical Quality of Life Index (PQLI)?

Accepted Answer

0 to 100

Answer

0 to 10

Answer

0 to 50

Answer

100 to 200

NEET-PG 2015 — Community Medicine