Study Design: Randomised Controlled Trials

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Questions and Answers

What is the primary advantage of conducting a randomized controlled trial (RCT)?

It guarantees that all subjects receive the most effective treatment.

It helps ensure that the treatment groups are balanced by subject characteristics. (correct)

It provides evidence that can only be strengthened through meta-analysis.

It allows for a comparison with existing active treatments.

Why is comparing an active agent against a placebo often seen as unfavorable?

It can introduce bias in treatment allocation.

It does not account for patient preferences.

It is considered unethical when another active agent exists. (correct)

It may not reflect real-world treatment scenarios.

What characteristic of randomized controlled trials aids in making blindness possible?

The allocation to treatment being unbiased. (correct)

The comparison with usual care.

The pooling of data in meta-analysis.

The use of computer randomization.

Which comparison group choice in a trial is likely to yield the least favorable results?

Comparison with another active agent. Signup and view all the answers

What is the role of randomization in RCTs?

To eliminate patient characteristics as confounding factors. Signup and view all the answers

In a randomized controlled trial, what is the typical method for random allocation?

Employing random number generation through a computer program. Signup and view all the answers

What ethical consideration must be taken into account when choosing a comparison group for an RCT?

Ensuring that the group does not receive an existing effective treatment. Signup and view all the answers

Which factor is NOT influenced by randomization in an RCT?

The occurrence of treatment side effects. Signup and view all the answers

What is the primary purpose of blinding in randomized controlled trials (RCTs)?

To avoid bias in reported outcomes Signup and view all the answers

Which statement accurately describes a double-blind trial?

Both the subject and assessor do not know the treatment allocation Signup and view all the answers

Why is randomization critical in maintaining blinding during RCTs?

It makes treatment allocation unpredictable Signup and view all the answers

In which scenario would blinding typically not be feasible?

Surgical procedures versus standard drug treatments Signup and view all the answers

What is an example of a placebo in drug trials?

An inert treatment indistinguishable from the active drug Signup and view all the answers

What could potentially bias the outcome in an RCT when participants are not blinded?

Assessors expecting one treatment to perform better Signup and view all the answers

What is one important role of randomization in RCTs apart from ensuring balanced groups?

To make blinding possible Signup and view all the answers

Which type of trial involves blinding the subject but not the assessor?

Single blind trial Signup and view all the answers

What approach ensures an unbiased comparison of treatment groups in a study?

Intention-to-treat (ITT) analysis Signup and view all the answers

Why should patients who change treatment still be analyzed in their original group?

Because change may relate to the treatment itself Signup and view all the answers

What is the potential downside of conducting a per-protocol analysis?

It may introduce bias by ignoring random allocation Signup and view all the answers

In the RCT evaluating allergenic food introduction, what was the primary outcome measured?

The frequency of food allergy development Signup and view all the answers

Which group introduced allergenic foods at an earlier age in the study?

Early-introduction-group Signup and view all the answers

What is generally a consequence of analyzing data according to the new treatment group after a patient changes treatment?

Loss of the initial balance in patient characteristics Signup and view all the answers

In the context of the RCT, what was the rationale for including allergenic foods in the infants' diets?

To determine if early introduction protects against food allergy Signup and view all the answers

What characterized the subjects in the study evaluating allergenic food introduction?

They were exclusively breastfed infants Signup and view all the answers

What is the primary goal of a cohort study?

To monitor risk factors in healthy individuals. Signup and view all the answers

Why might cohort studies be impractical for studying rare diseases?

They require a large number of subjects. Signup and view all the answers

In a prospective cohort study, when is risk factor data usually recorded?

Before the disease is confirmed. Signup and view all the answers

What is a significant challenge in maintaining cohort studies over long periods?

Difficulty in maintaining contact with subjects. Signup and view all the answers

What is the relationship between BMI and all-cause mortality based on the cohort study example provided?

Higher BMI is associated with a higher risk of death among never smokers. Signup and view all the answers

Which of the following describes a retrospective cohort study?

Using prior recorded data to analyze past conditions. Signup and view all the answers

What is required for a prospective cohort study to explore risk factors effectively?

Sufficient follow-up time for disease development. Signup and view all the answers

Which element is NOT typical in cohort studies?

A focus on a select population of patients. Signup and view all the answers

What was the percentage of participants in the standard-introduction group that developed food allergy?

7.1% Signup and view all the answers

In the per-protocol analysis, which allergen showed the highest percentage difference in allergy development between the standard and early-introduction groups?

Peanut Signup and view all the answers

Which statement about observational studies is true?

They focus on subjects receiving usual care without additional interventions. Signup and view all the answers

What was the conclusion regarding the efficacy of early introduction in food allergy prevention based on the intention-to-treat analysis?

Efficacy was not demonstrated. Signup and view all the answers

What is the primary focus of a case-control study?

Investigating causes or factors associated with a condition. Signup and view all the answers

Which food allergy showed the greatest reduction in occurrence according to the per-protocol analysis?

Egg Signup and view all the answers

What was the key limitation faced during the early introduction of all six intervention foods?

It was not easily achieved. Signup and view all the answers

In the development of food allergies, what weekly protein consumption was associated with lower occurrences for peanut and egg allergies?

2 grams Signup and view all the answers

Study Notes

Randomised Controlled Trials (RCTs)

RCTs are intervention studies where subjects are randomly assigned to treatment options, establishing them as the gold standard in research.
The choice of comparison group impacts trial interpretation; comparisons against placebos yield more favorable results than active agents.
Ethical standards dictate that comparison against placebo is inappropriate when effective active agents are available.
Usual care comparisons are common when the intervention involves a program of care, like stroke management pathways.
Randomization balances subject characteristics across treatment groups, minimizing bias and allowing for fair efficacy testing.
Employing random numbers via computer programs is a common method for random allocation in RCTs.
Blinding conceals treatment allocation, reducing bias from subjects or assessors affecting outcome reporting.
Double-blind trials involve concealment from both subjects and assessors, while single-blind trials involve concealment from one party only.
Proper concealment allows unbiased assessment of treatment effects, as known treatments may skew perceptions and data.
Placebos are inert treatments that mimic active treatments, facilitating blinding and unbiased assessments.
In certain trials, such as technology or surgical comparisons, blinding may not be feasible due to the nature of the intervention.

Intention to Treat Analysis

ITT analysis keeps subjects in their original treatment groups, maintaining balance in characteristics post-randomization.
This approach provides unbiased treatment comparisons, even if patients change treatments.
Results from per-protocol analysis (based on actual treatment received) can supplement ITT when patients deviate from original allocation.

Example RCT Study

A study with 1303 exclusively breastfed infants assessed early introduction of allergenic foods (peanut, egg, milk) vs. exclusive breastfeeding.
The primary outcome was food allergy prevalence by three years of age; ITT showed 7.1% vs. 5.6% (p=0.32) for standard vs. early introduction groups.
Per-protocol analysis indicated a significant reduction in food allergies linked to early introduction, particularly with peanuts and egg.
Study concluded early introduction of allergenic foods is safe but did not confirm efficacy in the intention-to-treat analysis.

Case-Control Studies

Observational studies avoid interventions, allowing subjects to remain in their natural state while observing outcomes.
Case-control studies identify disease causes by comparing patients with a specific condition ('cases') against a control group without the condition.
These studies are usually retrospective, collecting data about risk factors after disease identification.

Cohort Studies

Begins with healthy individuals who are followed over time to monitor disease incidence and risk factors.
Follow-up duration must be sufficient to observe enough cases to study risk factors effectively.
Cohort studies are typically prospective, recording risk factor data prior to disease confirmation but can also be retrospective with robust data collection.
Limitations include the need for large sample sizes, long follow-up periods, and potential resource intensity.

Example Cohort Study

A cohort study involving 527,265 individuals assessed the relationship between Body Mass Index (BMI) and mortality, specifically among non-smokers aged 50-71.
Higher midlife body weight was linked to increased mortality risk, highlighting the importance of BMI as a health factor.

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Description

This quiz covers the essential aspects of randomized controlled trials (RCTs), highlighting their significance as the 'gold standard' of research studies. Participants will learn about the design, implementation, and analysis of RCTs, along with the critical importance of choosing viable comparison groups.