"Alcohol Dependence To determine if topiramate is a safe and e...

Question

"Alcohol Dependence To determine if topiramate is a safe and effective treatment for alcohol dependence, researchers conducted a 14-week trial of 371 men and women aged 18 to 65 years diagnosed with alcohol dependence. In this double-blind, randomized, placebo-controlled experiment, subjects were randomly given either 300 milligrams (mg) of topiramate (183 subjects) or a placebo (188 subjects) daily, along with a weekly compliance enhancement intervention. The variable used to determine the effectiveness of the treatment was self-reported percentage of heavy drinking days. Results indicated that topiramate was more effective than placebo at reducing the percentage of heavy drinking days. The researchers concluded that topiramate is a promising treatment for alcohol dependence. Source: Bankole A. Johnson, Norman Rosenthal, et al. “Topiramate for Treating Alcohol Dependence: A Randomized Controlled Trial,” Journal of the American Medical Association, 298(14):1641–1651, 2007.

What does it mean for the experiment to be double-blind? Why do you think it is necessary for the experiment to be double-blind?"

What does it mean for the experiment to be double-blind? Why do you think it is necessary for the experiment to be double-blind?"

Accepted Answer

Hello there. Today we are going to solve the following practice problem together. So first off, let us read the problem and highlight all the key pieces of information that we need to use in order to solve this problem. A 12-week randomized clinical trial studied a new migraine medication on 240 adults. Participants were randomly assigned to receive either the active drug 120 subjects, or in an identical looking sugar pill, 120 subjects. Headache intensity was measured by self-reported daily pain scores on a scale from 0 to 10. The study was described as double blind. What does double blind mean in this context? And why is double blinding important for this trial? OK, so it appears for this particular problem, we're given a scenario, and in this scenario, we have a 12-week randomized clinical trial that is studying a new migraine medication on 240 adults. And based on the information that is provided to us about this particular clinical trial, we're asked to determine what does the term double blind mean in the context of this particular trial, and why is double blinding important for this particular problem. So now that we know what we're ultimately trying to solve for, Our first step that we need to take is we need to define what double blind means. So we need to recall and note that double blind is defined as either the participants nor the study personnel who interact with the participants or assesses outcomes know which treatment each participant receives. So that means Once again, so the participants nor the study personnel are knowing who's getting the placebo, the sugar pill, or who's getting the active drug. So we need to take this information that we know on our previous studies of double blind, and we need to apply this definition to the trial setting where the active drug and sugar pill are indistinguishable, meaning you're unable to tell them apart. So with that in mind, our second step now is we need to consider the placebo effect rule, which means, as we should recall, a blinded participant reduces bias from expectation, meaning that they're able to apply to the self-reported pain scores to show that the participant expectation could alter the reported intensity. So this means that if a participant knew that they were getting a sugar pill or a placebo at the fake medication, they may report having higher pain scores by default, but as they know for sure that they received the sugar pill and they know that they don't have the active drugs in the medication to treat their headaches, so they might score on the higher on the pain pain spectrum by default rather than. actually voting based on. Thinking that they actually got the actual drug and they're speaking more honestly to their pain. The pain that they're feeling rather than automatically dishing it because they know it's a fake pill. So with that in mind. Our 3rd 3rd step now, so that was our 2nd step. So our 3rd step now is we need to consider the observer expectancy rule. So the observer expectancy rule. So we need to note that the blinding of the investigators prevents their expectations from influencing participant encouragement. Data collection or assessment. So that means when we apply this to the staff we record and prompt daily pain scores, they're not being influenced because they do not know who's receiving what medication or who's receiving the sugar pill, who's receiving the actual active drug. So it makes them non-biased. So that will mean for our 4th step now, so this is step number 4, we need to consider the and recall the internal validity rule, meaning that blinding will reduce non-treatment sources of systematic. Differences between groups and when we applied this to when we apply this to the experiment itself we could conclude that the observed differences in pain are more likely due to the medication itself rather than internal or external bias. So that will mean for our 5th and final step, we can make our final conclusions. That will mean that because the outcome is subjective, based on the self-reporting, double blinding is necessary in this particular experimental trial. To minimize both participant and investigator biases that would otherwise threaten the study's conclusions. So that will mean that our final answer without a doubt will be the following. So, once again, our final answer will be as follows. Double blind means neither the participants nor the investigators who interact with them know the assignments. It is important because it prevents both placebo effects and observer expectancy effects that could bias self-reported pain scores, and that's it. We've officially solved for this problem. Hooray, we did it. Thank you so much for watching. Hopefully that helped and I can't wait to see you in the next video. Bye.

Key Concepts

Double-Blind Experiment

Randomization

Placebo Control

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