6 ms·

"The purpose of the placebo group is to account for the placebo effect, that is, effects from treatment that do not depend on the treatment itself" https://en.

by bobbles 11y ago

"The purpose of the placebo group is to account for the placebo effect, that is, effects from treatment that do not depend on the treatment itself" https://en.wikipedia.org/wiki/Placebo-controlled_study https://en.wikipedia.org/wiki/Placebo-controlled_study

protomyth 11y ago
Yeah, I know the purpose, but I'm really still having a tough time seeing any actual justification when we know how bad a diseases is. I cannot think of a reason it is worth it. I worked in clinical trials briefly (9 months) and still think its a level of cruel that borders on inhuman. "I'm sorry, we know the disease / condition kills, but we gave your loved one sugar pills".
- ekianjo 11y ago
  The dengue fever does not kill most of the time. It makes you paralyzed with high fever for one to two weeks, but usually it does not kill you, unless you are already old and weak. I'm pretty sure that the recruitment for the clinical trial can ensure that only healthy people with appropriate constitution would not die from dengue fever.
  - protomyth 11y ago
    Don't we actually have enough data on the dengue fever to tell exactly what will happen to the control group? I don't think this is an actual unknown anymore.
    - ghshephard 11y ago
      So - what would you conclude if both the control group and the vaccine group didn't contract dengue during the trial?
    - ekianjo 11y ago
      Again, it is probably known - You would need to ask an expert, but I wage there are probably good reasons for having a control group, that we may not be aware of. I think the ethical question you raised is a serious concern in any clinical trial, so I would be very surprised if it is not addressed at any point by the trials's sponsors.
- wbl 11y ago
  "I'm sorry, we gave your loved one a treatment that's actually harmful, because we didn't compare to the right group".
  - protomyth 11y ago
    They were doing a study and were going to give it out. I just don't believe that we don't already have the dataset of the control group.
- pak 11y ago
  For this trial, the placebo and treatment groups are both composed of healthy volunteers that are exposed to a controlled amount of an attenuated dengue virus (called rDEN2Δ30). All groups in the trial are told the risks of exposure to the virus. Because the virus is attenuated (weakened), the risk of severe sickness is very very low. The point of using an attenuated virus is that this is a "challenge model" that is supposed to simulate an exposure to the real virus closely enough that one can judge if the vaccine is likely working, without exposing the patients to the risks of infection by the full-strength virus. CNN did a much better job than Wired in explaining this. http://www.cnn.com/2016/03/16/health/dengue-vaccine-effective/index.html http://www.cnn.com/2016/03/16/health/dengue-vaccine-effectiv... Therefore, the fact that the placebo group had certain levels of various symptoms (according to the article, 80% had a rash, 20% had nausea, etc.) is still important data for other scientists who are trying to judge if they should use the rDEN2Δ30 challenge model in their candidate vaccine trials. It's not intended to provide data on what natural dengue fever is like, which I agree would be unethical and unnecessary.
ekianjo 11y ago
Placebo controlled groups are not used for Cancer treatments, though. So it's not an universal rule.
- refurb 11y ago
  That's because there are current treatments that can act as the control arm. In a cancer trial you'd typically compare standard of care with the new drug.
  - ekianjo 11y ago
    No, there is also an ethical concern behind it. We already know the survival rate per months for most cancers so there is no need to have a placebo group anyway. For cancer patients on trial we only want to offer a potential upside (once the drug is confirmed to be safe for use). Plus, there are some cancers out there with very few working treatments (so no real SoC) - If SoC is not available you would not consider a placebo group anyway.
    - refurb 11y ago
      Can you give some examples of trials where there wasn't a control arm (e.g. placebo or SOC)? I agree actual placebos are rare since there is always something you can give to a cancer patient, even if it doesn't work well. What I haven't seen is a clinical trial without a control arm. In terms of the ethical considers it's not unusual to run a trial for a yeat and then switch every patient over to the new drug.

by bobbles 11y ago

protomyth 11y ago

Yeah, I know the purpose, but I'm really still having a tough time seeing any actual justification when we know how bad a diseases is. I cannot think of a reason it is worth it. I worked in clinical trials briefly (9 months) and still think its a level of cruel that borders on inhuman. "I'm sorry, we know the disease / condition kills, but we gave your loved one sugar pills".

ekianjo 11y ago
The dengue fever does not kill most of the time. It makes you paralyzed with high fever for one to two weeks, but usually it does not kill you, unless you are already old and weak. I'm pretty sure that the recruitment for the clinical trial can ensure that only healthy people with appropriate constitution would not die from dengue fever.
- protomyth 11y ago
  Don't we actually have enough data on the dengue fever to tell exactly what will happen to the control group? I don't think this is an actual unknown anymore.
  - ghshephard 11y ago
    So - what would you conclude if both the control group and the vaccine group didn't contract dengue during the trial?
  - ekianjo 11y ago
    Again, it is probably known - You would need to ask an expert, but I wage there are probably good reasons for having a control group, that we may not be aware of. I think the ethical question you raised is a serious concern in any clinical trial, so I would be very surprised if it is not addressed at any point by the trials's sponsors.
wbl 11y ago
"I'm sorry, we gave your loved one a treatment that's actually harmful, because we didn't compare to the right group".
- protomyth 11y ago
  They were doing a study and were going to give it out. I just don't believe that we don't already have the dataset of the control group.
pak 11y ago
For this trial, the placebo and treatment groups are both composed of healthy volunteers that are exposed to a controlled amount of an attenuated dengue virus (called rDEN2Δ30). All groups in the trial are told the risks of exposure to the virus. Because the virus is attenuated (weakened), the risk of severe sickness is very very low. The point of using an attenuated virus is that this is a "challenge model" that is supposed to simulate an exposure to the real virus closely enough that one can judge if the vaccine is likely working, without exposing the patients to the risks of infection by the full-strength virus. CNN did a much better job than Wired in explaining this. http://www.cnn.com/2016/03/16/health/dengue-vaccine-effective/index.html http://www.cnn.com/2016/03/16/health/dengue-vaccine-effectiv... Therefore, the fact that the placebo group had certain levels of various symptoms (according to the article, 80% had a rash, 20% had nausea, etc.) is still important data for other scientists who are trying to judge if they should use the rDEN2Δ30 challenge model in their candidate vaccine trials. It's not intended to provide data on what natural dengue fever is like, which I agree would be unethical and unnecessary.

ekianjo 11y ago

Placebo controlled groups are not used for Cancer treatments, though. So it's not an universal rule.

refurb 11y ago
That's because there are current treatments that can act as the control arm. In a cancer trial you'd typically compare standard of care with the new drug.
- ekianjo 11y ago
  No, there is also an ethical concern behind it. We already know the survival rate per months for most cancers so there is no need to have a placebo group anyway. For cancer patients on trial we only want to offer a potential upside (once the drug is confirmed to be safe for use). Plus, there are some cancers out there with very few working treatments (so no real SoC) - If SoC is not available you would not consider a placebo group anyway.
  - refurb 11y ago
    Can you give some examples of trials where there wasn't a control arm (e.g. placebo or SOC)? I agree actual placebos are rare since there is always something you can give to a cancer patient, even if it doesn't work well. What I haven't seen is a clinical trial without a control arm. In terms of the ethical considers it's not unusual to run a trial for a yeat and then switch every patient over to the new drug.