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Randomized And Double-Blind!

The world of clinical trials is interesting, elaborate, confusing and interesting.  You have your placebos and shams, endpoints and eligibility criteria, informed consent and participant protection.  You have your big budgets and peer reviews and protocols and published findings.  Most of us believe we understand something of how these studies work, but unless we’ve actually designed a few of them, we probably don’t know as much as we should.

Okay, then, a very quick review.  Some of the common elements of clinical trials include:

  • Studies can be randomized.  What does this mean, exactly?  In a randomized trial, each study participant is assigned by chance, according to a computer result or a table of random numbers, to either a control group or an investigational group.  This is to help make sure the results of the study can be safely attributed to the treatment or therapy and not to other unrelated factors that could skew or bias the outcome or the interpretation of the findings.  Each participant has a 50/50 chance of being placed in either group.  Complex trials often involve several groups.
  • Trials are often double-blind.  Double blind means that neither the researchers themselves nor the participants know who has been assigned where.   Again, this approach helps reduce the chances of any bias or previous information from influencing study results.  The assignment records are kept on file; should the research team need to find out who is getting an active treatment they will be able to do so.
  • Clinical trials are designed by the researchers to have one or more endpoints.  An endpoint is a measure to determine whether or not a treatment or therapy being studied has an important or beneficial effect.  With an acupuncture treatment, for example, an endpoint is whether the treatment of a patient with pain actually relieves or reduces that pain.
What about placebos?
This is a fascinating and poorly understood area.  Basically, a placebo is an inactive treatment.  Placebos play a vital role in clinical trials, and not just because of the ‘placebo effect’, which involves a participant’s expectations about a treatment influencing their response (I expect this to work, so it does!).  Many illnesses and symptoms go away all on their own – another part of the challenge of the ‘placebo effect’.
 Researchers work very hard to separate these issues from the effects of the treatment being studied.  One way to do this is to give one group of participants a placebo – say, a capsule that looks just like the real thing but is made up of sugar – and the other group the active treatment.  The responses of the groups are then compared and contrasted to help the researchers understand the real treatment’s effects.
A ‘sham’ is another sort of placebo, used when the treatment being investigated is a procedure rather than a drug or other substance.  Acupuncture would be such a procedure.  The sham procedure mimics the look and feel of the active procedure but does not have any active treatment elements.  Again, with acupuncture as the example, the sham procedure could place acupuncture needles in areas of the body where no therapeutic response is expected.
What about trial participants?
Eligibility criteria means the rules for those who can, and cannot, participate in a study.   Each clinical trial sets is own unique criteria.  The purpose of this is to sort out and identify participants appropriate for the research study, based on those questions and challenges the researchers are trying to answer and solve.  Examples of eligibility criteria include:
  • History of prior treatment
  • Presence of other illnesses
  • Type or severity of disease
Many clinical trials include a broad range of participants, people of various ages, both genders and from different ethnicities.  This means any results can apply to the general population.  Of course, should a study be more targeted or limited to a specific group within the population – women of child-bearing age or the elderly, for example – the criteria would be more specific and limiting.  
There are also important safety concerns to address when setting up eligibility criteria.  Clinical trials need to be as risk-free as possible for the participants.  An individual with a serious illness or condition may not be able to safely participate in a particular study if participating means they would have to stop taking their regular medications.  At the same time, eligibility criteria are never used to exclude a potential study participant for reasons not directly related to the research study itself.
Next up, more about protections for study participants, the informed consent process and what happens during a typical trial.
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