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Chapter 4: Problem 95

Issues in clinical trials A randomized clinical trial is planned for AIDS patients to investigate whether a new treatment provides improved survival over the current standard treatment. It is not known whether it will be better or worse. a. Why do researchers use randomization in such experiments, rather than letting the subjects choose which treatment they will receive? b. When patients enrolling in the study are told the purpose of the study, explain why they may be reluctant to be randomly assigned to one of the treatments.

Short Answer

Expert verified
Researchers use randomization to eliminate bias, while patients may hesitate due to lack of control over treatment choice.

Step by step solution

01

Understanding Randomization

Randomization is used in clinical trials to eliminate bias and ensure that the two groups being compared are equivalent at the start of the experiment. By randomly assigning participants to either the experimental or control group, researchers can minimize the effects of confounding variables. This helps in making the study results more reliable and valid by ensuring that differences in outcomes can be attributed to the treatment rather than other factors.
02

Overcoming Patient Preference

When participants are told the purpose of a clinical trial, they might be hesitant to receive a random treatment. Patients may prefer one treatment over another due to their own beliefs, perceptions about the effectiveness of treatments, or fear of unknown side effects. This reluctance can be due to a perceived lack of control over their healthcare decisions, especially when one treatment is already established as a standard or has public perception as more effective.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Randomization
In clinical trials, randomization is a crucial process that helps ensure the integrity of a study. When researchers conduct a trial, they aim to determine whether a new treatment is more effective than an existing one. To do this without bias, participants must be randomly assigned to either the experimental group receiving the new treatment or the control group receiving the standard treatment.

This method serves several purposes:
  • It eliminates selection bias, ensuring that the two groups are comparable from the start.
  • It permits the control of both known and unknown confounding variables, which are factors that might affect the outcome.
  • It enhances the validity and reliability of the trial results by attributing observed effects directly to the treatment under investigation.
By leveraging randomization, researchers can be more confident that differences in outcomes are due to the treatment and not other extraneous factors.
Bias Elimination
Bias can skew the results of a clinical trial and lead to incorrect conclusions about the efficacy of a treatment. Bias elimination is one of the primary objectives of a well-designed clinical study.

This is why randomization takes the wheel鈥攊t helps:
  • Prevent systematic differences between groups, ensuring that any variances are due to chance rather than intentional or unintentional actions by researchers or participants.
  • Promote objectivity, allowing for an unbiased comparison between the two treatment groups.
  • Provide a credible basis for statistical analysis, which is essential for drawing valid conclusions from the data.
By minimizing bias, the study can offer more accurate insights into the true effects of the new treatment.
Patient Reluctance
When patients are informed about the purpose of a clinical trial, they may experience hesitation in participating due to the process of random assignment. This reluctance is often rooted in several personal and psychological factors:

  • Patients may have biases or preconceived notions about which treatment is better based on public opinion or their own research.
  • The thought of receiving a treatment based on random selection can feel unsettling, particularly if the new treatment has unknown side effects.
  • There's a sense of losing control over personal healthcare decisions, as patients might prefer to choose their treatment path.
To mitigate these concerns, researchers must ensure clear communication about the study's purpose, the randomization process, and the potential risks and benefits.
Confounding Variables
In any research study, confounding variables can pose significant threats to the validity of the findings. These variables, which are factors other than the treatment being tested, can influence the outcomes of the study if not properly controlled.

Randomization plays a key role in addressing these issues:
  • It ensures that confounding variables are evenly distributed across treatment groups, reducing their potential impact on the results.
  • This equal distribution allows researchers to be more confident that observed effects are due to the treatment itself.
  • Without controlling for these variables, conclusions drawn from the study could be misleading, attributing effects to the treatment when they might actually result from other factors.
Effectively managing confounding variables is fundamental to achieving reliable and valid clinical trial outcomes.

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Most popular questions from this chapter

Smoking and lung cancer Refer to the smoking case-control study in Example \(9 .\) Since subjects were not matched according to all possible lurking variables, a cigarette company can argue that this study does not prove a causal link between smoking and lung cancer. Explain this logic, using diet as the lurking variable.

Vitamin B A New York Times article (March 12, 2006) described two studies in which subjects who had recently had a heart attack were randomly assigned to one of four treatments: placebo and three different doses of vitamin B. In each study, after years of study, the differences among the proportions having a heart attack were judged to be not statistically significant. Identify the (a) response variable, (b) explanatory variable, (c) experimental units, (d) treatments, and (e) explain what it means to say that differences "were judged to be not statistically significant."

Bias due to perceived race A political scientist at the University of Chicago studied the effect of the race of the interviewer. \(^{8}\) Following a phone interview, respondents were asked whether they thought the interviewer was black or white (all were actually black). Perceiving a white interviewer resulted in more conservative opinions. For example, \(14 \%\) agreed that "American society is fair to everyone" when they thought the interviewer was black, but \(31 \%\) agreed to this statement when posed by an interviewer that the respondent thought was white. Which type of bias does this illustrate: Sampling bias, nonresponse bias, or response bias? Explain.

Never leave home without duct tape There have been anecdotal reports of the ability of duct tape to remove warts. In an experiment conducted at the Madigan Army Medical Center in the state of Washington ( Archives of Pediatric and Adolescent Medicine \(2002 ; 156: 971-974)\), 51 patients between the ages of 3 and 22 were randomly assigned to receive either duct-tape therapy (covering the wart with a piece of duct tape) or cryotherapy (freezing a wart by applying a quick, narrow blast of liquid nitrogen). After two months, the percentage successfully treated was \(85 \%\) in the duct tape group and \(60 \%\) in the cryotherapy group. a. Identify the response variable, the explanatory variable, the experimental units, and the treatments. b. Describe the steps of how you could randomize in assigning the 51 patients to the treatment groups.

Smoking and death Example 1 in Chapter 3 described a survey of 1314 women during \(1972-1974\), in which each woman was asked whether she was a smoker. Twenty years later, a follow-up survey observed whether each woman was deceased or still alive. Was this study a retrospective study, or a prospective study? Explain.
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