NEET-PG 2015 - Community Medicine Practice Questions

Q: Which of the following is NOT one of Bradford Hill's criteria for causation?

Absence of temporal relationship. ***Absence of temporal relationship*** - Bradford Hill's criteria include **temporality** (temporal relationship), which states that the cause must precede the effect in time. - The criterion is the **presence** of a temporal relationship, not its absence. - "Absence of temporal relationship" is therefore NOT one of Bradford Hill's criteria—it is the opposite of what the criterion requires. - This is the correct answer to this "NOT" question. *Strength of association* - This **IS** one of Bradford Hill's criteria. - It refers to the **magnitude of the association** between exposure and outcome (measured by relative risk, odds ratio, etc.). - A stronger association provides more evidence for causality. *Consistency of association* - This **IS** one of Bradford Hill's criteria. - It means the association is observed **repeatedly** across different studies, populations, settings, and times. - Consistent replication strengthens the causal argument. *Specificity of association* - This **IS** one of Bradford Hill's criteria. - It suggests that a specific exposure leads to a specific outcome with limited alternative explanations. - While supportive of causation, Hill noted this criterion is less essential as many exposures have multiple effects.

Q: What is the most common mode of transmission of HIV?

Sexual contact. ***Sexual contact*** - **Unprotected sexual intercourse**, both heterosexual and homosexual, is overwhelmingly the most common way HIV is transmitted globally. - The virus can be exchanged through **bodily fluids** such as semen, vaginal fluids, and rectal fluids during sexual activity. - Accounts for approximately **80% of new HIV infections** worldwide. *Occupational exposure (needle stick injury)* - While a recognised mode of transmission, **needle stick injuries** account for a very small percentage of total HIV infections, primarily affecting healthcare workers. - The risk of transmission per exposure is relatively low (approximately **0.3%**), especially compared to sexual contact. *Perinatal transmission (mother to child)* - **Mother-to-child transmission** can occur during pregnancy, childbirth, or breastfeeding. - Although significant, especially in resource-limited settings, global efforts and **PMTCT programs** have resulted in a significant reduction in this type of transmission. *Transmission via blood and blood products* - This mode was once a major concern but is now extremely rare in countries with robust **blood screening programs**. - While sharing contaminated needles among **intravenous drug users** remains a risk, transfusion-related HIV is largely controlled.

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: Which one of the following is NOT a utilization rate?

Population bed ratio. ***Population bed ratio*** - The **population bed ratio** indicates the number of available beds per unit of population, reflecting healthcare **resource availability** rather than resource utilization. - It is a measure of healthcare capacity and access, not how intensively those beds are being used. *Bed occupancy rate* - The **bed occupancy rate** measures the proportion of available hospital beds that are occupied over a given period, directly indicating the **utilization** of bed resources. - A higher rate suggests more efficient use of beds, while a lower rate may indicate underutilization or excess capacity. *Bed turnover ratio* - The **bed turnover ratio** calculates the number of patients discharged per bed over a specific period, reflecting how frequently beds are being used and re-used. - It indicates the **efficiency** with which beds are being utilized and cleared for new patients. *Average length of stay* - The **average length of stay (ALOS)** represents the average number of days a patient remains hospitalized, which directly relates to the **duration of bed utilization** per patient. - A shorter ALOS can indicate more efficient use of beds, while a longer ALOS may suggest higher resource consumption per patient.

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: Human, animal, fomite or objects from which infective organism enters the host is called?

Source of infection. ***Source of infection*** - The **source of infection** refers to the person, animal, object, or substance from which an infectious agent passes immediately to a host. - This can include humans, animals, fomites, or contaminated objects that directly transmit the infectious organism. - This is the proximate source from which the agent enters the host. *Infective Reservoir* - An **infective reservoir** is the long-term habitat where an infectious agent normally lives, grows, and multiplies. - The reservoir can be human, animal, plant, soil, or inanimate matter where the agent is normally found. - While a reservoir can be a source, the source is specifically the immediate point from which transmission occurs. *Infective Carrier* - An **infective carrier** is an infected person or animal that harbors a specific infectious agent without showing clinical symptoms but can transmit it to others. - A carrier is a type of source (when transmission occurs from them), but the term "source" is broader, encompassing inanimate objects and fomites as well. *None of the above* - This option is incorrect because **Source of infection** accurately describes the concept presented in the question.

Question 1

Which of the following is NOT one of Bradford Hill's criteria for causation?

Accepted Answer

Absence of temporal relationship

Answer

Consistency of association

Answer

Specificity of association

Answer

Strength of association

Question 2

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 3

What is the most common mode of transmission of HIV?

Accepted Answer

Sexual contact

Answer

Occupational exposure (needle stick injury)

Answer

Perinatal transmission (mother to child)

Answer

Transmission via blood and blood products

Question 4

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 5

Which one of the following is NOT a utilization rate?

Accepted Answer

Population bed ratio

Answer

Bed occupancy rate

Answer

Bed turnover ratio

Answer

Average length of stay

Question 6

What is the definition of a reservoir in the context of infectious diseases?

Accepted Answer

Person, animal or substance in which infectious agent lives and multiplies

Answer

Person, animal or object from which infectious agent is transmitted to host

Answer

Person or animal in which infectious agent causes a disease

Answer

Person or animal that transmits the infectious agent mechanically

Question 7

Most commonly used blinding technique in epidemiological studies?

Accepted Answer

Double blinding

Answer

None of the options

Answer

Single blinding

Answer

Triple blinding

Question 8

Which of the following statements is true regarding a combined prospective-retrospective study?

Accepted Answer

Retrospective identification of cohort followed by prospective follow-up

Answer

Only prospective follow-up from current time point

Answer

Cross-sectional assessment at a single time point

Answer

Only retrospective data collection from past records

Question 9

What is the definition of Population Attributable Risk?

Accepted Answer

The difference between incidence in population and incidence in non-exposed.

Answer

The difference between incidence in population and incidence in exposed.

Answer

The difference between incidence in population and incidence in non-exposed compared with incidence in exposed.

Answer

The difference between incidence in exposed and incidence in non-exposed.

Question 10

Human, animal, fomite or objects from which infective organism enters the host is called?

Accepted Answer

Source of infection

Answer

Infective Reservoir

Answer

Infective Carrier

Answer

None of the above

NEET-PG 2015 — Community Medicine