Randomized Controlled Trials (RCTs) in Research
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Questions and Answers

What is the primary purpose of randomization in RCTs?

  • To minimize bias in treatment allocation (correct)
  • To ensure patients receive the best treatment
  • To compare the study results with other studies
  • To justify the use of placebo in treatment

    • What is the advantage of comparing an active agent with an inert substance or placebo?

  • It reduces the cost of the trial
  • It gives a more favourable result (correct)
  • It provides more accurate results
  • It is more ethical

    • Why is it generally considered unethical to compare an active agent with a placebo when an existing active agent is available?

  • It is less accurate
  • It deprives patients of a proven treatment (correct)
  • It is more expensive
  • It is more time-consuming

    • What is the common practice when an intervention is a programme of care?

    <p>To compare it with the usual care</p> Signup and view all the answers

    What is the benefit of randomization in terms of blindness?

    <p>It makes blindness possible</p> Signup and view all the answers

    What is the usual way to do random allocation in RCTs?

    <p>By using a computer programme based on random numbers</p> Signup and view all the answers

    What is the 'gold standard' of individual research studies?

    <p>Randomized controlled trials</p> Signup and view all the answers

    What is the ultimate goal of randomization in RCTs?

    <p>To minimize bias and ensure fairness in the trial</p> Signup and view all the answers

    What is the primary purpose of blinding in RCTs?

    <p>To avoid conscious or unconscious bias in reported outcomes</p> Signup and view all the answers

    What is a characteristic of a single-blind trial?

    <p>The treatment allocation is concealed from either the subject or the assessor, but not both</p> Signup and view all the answers

    Why is randomization important in RCTs?

    <p>It makes blindness possible</p> Signup and view all the answers

    What is the primary purpose of a placebo in drug trials?

    <p>To enable blinding of both the subject and assessor</p> Signup and view all the answers

    In which type of trials is blinding not possible?

    <p>Trials of surgical interventions</p> Signup and view all the answers

    What is the consequence of not blinding in RCTs?

    <p>Increased conscious or unconscious bias in reported outcomes</p> Signup and view all the answers

    What is the role of the assessor in a double-blind trial?

    <p>To remain unaware of which treatment is being given</p> Signup and view all the answers

    What is the primary advantage of using a placebo in RCTs?

    <p>It enables blinding of both the subject and assessor</p> Signup and view all the answers

    What is the primary analysis in a Randomized Controlled Trial (RCT)?

    <p>Direct comparison of the treatment groups, including subjects in the group to which they were originally allocated</p> Signup and view all the answers

    Why is ITT analysis important in RCTs?

    <p>It provides an unbiased comparison of the treatments</p> Signup and view all the answers

    What happens if patients' data are analyzed as if they were in their new treatment group?

    <p>The balance in patient characteristics which was present after random allocation will be lost</p> Signup and view all the answers

    What is the purpose of per-protocol analysis in addition to ITT analysis?

    <p>To evaluate the effect of the treatment in patients who followed the assigned protocol</p> Signup and view all the answers

    What was the primary outcome measured in the RCT evaluating the introduction of allergenic foods to babies?

    <p>The proportion of participants with food allergy to one or more of the six foods, by three years of age</p> Signup and view all the answers

    Why were patients in the standard-introduction-group advised to follow the United Kingdom recommendation?

    <p>To follow exclusive breastfeeding to around six months of age</p> Signup and view all the answers

    What was the age of the infants recruited for the RCT?

    <p>Three months old</p> Signup and view all the answers

    How many allergenic foods were introduced to the infants in the early-introduction-group?

    <p>Six</p> Signup and view all the answers

    In a cohort study, what is the primary reason for selecting a large number of subjects?

    <p>To obtain enough individuals who get the disease or condition</p> Signup and view all the answers

    What is the main advantage of a prospective cohort study?

    <p>It allows for the collection of risk factor data before the disease is confirmed</p> Signup and view all the answers

    What is a major difficulty with cohort studies?

    <p>Maintaining contact with subjects over a long period</p> Signup and view all the answers

    In a retrospective cohort study, what is a requirement for the data?

    <p>Full risk factor data must be obtained on all individuals with and without the disease</p> Signup and view all the answers

    What is the primary outcome of interest in the cohort study example provided?

    <p>The relationship between BMI and all-cause mortality</p> Signup and view all the answers

    Why is it necessary to follow up subjects in a cohort study for a sufficient amount of time?

    <p>To allow sufficient subjects to get the disease and risk factors to be explored</p> Signup and view all the answers

    What is a limitation of cohort studies when it comes to rare diseases?

    <p>The study may not be feasible due to the length of follow-up required</p> Signup and view all the answers

    What is a key feature of a cohort study in terms of the relationship between the risk factor and the disease?

    <p>The incidence of disease can be related directly to the presence of the risk factor</p> Signup and view all the answers

    What is a limitation of design in case-control studies?

    <p>The choice of control group affects the comparisons between cases and controls</p> Signup and view all the answers

    What is the main difference between a case-control study and a cohort study?

    <p>The direction of the study, from cause to effect or from effect to cause</p> Signup and view all the answers

    What is the odds ratio reported in the study about genitourinary infections and gastroschisis?

    <p>2.02</p> Signup and view all the answers

    What is the purpose of a cohort study?

    <p>To investigate the causes of a disease</p> Signup and view all the answers

    What is a limitation of case-control studies in terms of data collection?

    <p>Data is usually collected retrospectively and may be incomplete, inaccurate, or biased</p> Signup and view all the answers

    What was the purpose of the study on genitourinary infections and gastroschisis?

    <p>To establish a correlation between genitourinary infections and gastroschisis</p> Signup and view all the answers

    What is the advantage of a cohort study over a case-control study?

    <p>A cohort study can establish causality between the risk factor and the outcome</p> Signup and view all the answers

    What was the result of the study on genitourinary infections and gastroschisis?

    <p>There was a positive association between genitourinary infections and gastroschisis</p> Signup and view all the answers

    Study Notes

    Randomized Controlled Trials (RCTs)

    • RCTs are the "gold standard" of individual research studies, providing sound evidence about treatment efficacy.
    • In RCTs, subjects are randomly allocated to treatment options to ensure unbiased allocation.
    • The choice of comparison group affects how we interpret evidence from a trial.
    • Comparison of an active agent with an inert substance or placebo is likely to give a more favorable result than comparison with another active agent.
    • Comparison with 'usual care' is common when an intervention is a program of care.

    Randomization in RCTs

    • Randomization ensures that the subjects' characteristics do not affect which treatment they receive.
    • Allocation to treatment is unbiased, and differences between groups can be attributed to the treatments alone.
    • Randomization makes blindness possible.
    • Random allocation is usually done using a computer program based on random numbers.

    Blinding in RCTs

    • Blinding is when the treatment allocation is concealed from either the subject or assessor or both.
    • Blinding is done to avoid conscious or unconscious bias in reported outcomes.
    • A trial is double-blind if neither the subject nor the assessor knows which treatment is being given.
    • A trial is single-blind if the treatment allocation is concealed from either the subject or the assessor but not both.

    Intention to Treat Analysis

    • Intention-to-treat (ITT) analysis is the primary analysis of RCTs, where subjects are included in the group to which they were originally allocated.
    • ITT analysis provides an unbiased comparison of the treatments.
    • If patients change treatment, they should still be analyzed together with patients in their original, randomly allocated group.

    Example of RCT

    • An RCT evaluated whether introducing allergenic foods to babies at 3 months vs 6 months affects allergy.
    • 1303 exclusively breastfed three-month-old infants were randomly assigned to introduce six allergenic foods or to follow the UK recommendation of exclusive breastfeeding to around six months of age.

    Limitations of Design

    • The choice of control group affects the comparisons between cases and controls.
    • Exposure to risk factor data is usually collected retrospectively and may be incomplete, inaccurate, or biased.

    Case Control Study

    • A case-control study investigates the association between a risk factor and a disease.
    • Subjects are selected based on their disease status (cases) and compared to a control group.
    • Example: A study investigated the association between genitourinary infections in the month before conception to the end of the first trimester, and gastroschisis.

    Cohort Study

    • A cohort study is an observational study that aims to investigate causes of disease or factors related to a condition.
    • It starts with an unselected group of individuals who are followed up for a set period of time.
    • Example: A cohort study examined the relationship between BMI and all-cause mortality in 527,265 U.S. men and women in the National Institutes of Health–AARP cohort.

    Difficulties with Cohort Studies

    • A large number of subjects is needed to obtain enough individuals who get the disease or condition.
    • The length of follow-up may be substantial to get enough diseased individuals.
    • There is difficulty in maintaining contact with subjects, particularly if the follow-up is lengthy.
    • The resources required may be very high.

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    Related Documents

    Study Design Notes PDF

    Description

    Learn about the benefits and methods of Randomized Controlled Trials, the gold standard of individual research studies, and how they provide unbiased evidence about treatment efficacy.

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