NEET-PG 2015 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 important criterion in a causal relationship hypothesis?

Temporal association. ***Temporal association*** - This is the **sine qua non** of causality, meaning the exposure or cause must always precede the outcome or effect in time. - Without the exposure occurring before the disease, a causal link cannot be established, even if other criteria are met. *Coherence of association* - This refers to the consistency of findings with current scientific knowledge and **biological plausibility**. - While important for supporting causality, a coherent explanation is not sufficient in itself to prove causation and may even be misleading if current knowledge is incomplete. *Specificity of association* - This criterion suggests that a single exposure should lead to a single outcome, or a single outcome should be caused by a single exposure. - However, many diseases have **multiple causes**, and many exposures can lead to multiple effects, making this a weak criterion in modern epidemiology. *Strength of association* - A **strong association**, often measured by a high relative risk or odds ratio, makes a causal relationship more likely but does not guarantee it. - Strong associations can still be due to **confounding factors** or bias, and weak associations can be causal.

Q: What is the primary benefit of screening for diseases?

Early detection of diseases. ***Early detection of diseases*** - This is the **primary benefit** and defining purpose of **screening programs** in public health. - Screening identifies diseases in their **presymptomatic or early stage** when individuals are apparently healthy, allowing for intervention before clinical symptoms appear. - According to epidemiological principles, the goal of screening is to detect disease **earlier than it would be found through routine clinical practice**. - Early detection enables better prognosis through **lead time** and **length time bias** advantages. *Timely treatment of identified conditions* - While treatment is the **ultimate goal** of healthcare, it is not specific to screening—treatment occurs whether disease is found through screening or clinical presentation. - Treatment is the **consequence** of early detection, not the primary benefit of the screening process itself. - The unique value of screening lies in **detection**, not treatment per se. *Providing support for patients after diagnosis* - **Patient support** is an important aspect of healthcare but is not the purpose of screening programs. - This is **post-diagnostic care**, which follows after the screening process has identified cases. *Identifying all potential cases of a disease* - **Screening tests** cannot identify all cases due to inherent limitations in **sensitivity** and **specificity**. - Screening aims to identify a significant proportion of cases in a population, accepting that some will be missed (**false negatives**) and some healthy individuals may test positive (**false positives**).

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: 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: 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: 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.

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

What is the most important criterion in a causal relationship hypothesis?

Accepted Answer

Temporal association

Answer

Coherence of association

Answer

Specificity of association

Answer

Strength of association

Question 3

What is the primary benefit of screening for diseases?

Accepted Answer

Early detection of diseases

Answer

Providing support for patients after diagnosis

Answer

Identifying all potential cases of a disease

Answer

Timely treatment of identified conditions

Question 4

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 5

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 6

Most commonly used blinding technique in epidemiological studies?

Accepted Answer

Double blinding

Answer

None of the options

Answer

Single blinding

Answer

Triple blinding

Question 7

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 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

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

NEET-PG 2015

Community Medicine