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Friday, August 21, 2015

Clinical Trials Made Easy

In the ancient world, and throughout most of history, whether or not a medicine worked was determined by speculation.  In the modern world, it is determined by a clinical trial.  Let us assume that albuterol is the medicine being tested, and we will walk you through the process.

In order to find out if albuterol actually makes asthmatics feel better, we have to have something to compare albuterol with. For this reason, we are going to create two groups:
  • Experimental Group.  When a medicine is tested, these are the individuals who actually get to take the medicine.  If albuterol were being tested, these folks would actually get the medicine. 
  • Control Group.  When a medicine is tested, these are the individuals who do not get to take the actual medicine.  They take a placebo instead.  This is needed so the examiners have something to compare the results with. If albuterol were being tested, these folks would just inhale normal saline.
  • Tested Drug. Albuterol with 3 cc normal saline
  • Comparator.  Normal Saline
  • Placebo.  The comparator. A harmless or fake medicine. 
  • Null Hypothesis.  To begin, experimenters will assume that both the tested drug and the comparator are equal, that there is no difference between the two.  The study will then prove whether this is true, or whether the tested drug generates a benefit. 
So now let us assume that all the people in the experimental group and all the patients in the control group have been diagnosed with moderate to severe asthma and have uncontrolled asthma.  None of the patients have taken any asthma medicine within the previous 12 hours.  Pulmonary function testing is done on all the patients, followed by a period of 20 minutes of rest.  The experimental group is then given the tested drug (albuterol with 3cc of normal saline) and the control group is given the placebo (3cc normal saline). Both the tested drug and the placebo are inhaled over 10 minutes using a nebulizer. 

All the patients now take another pulmonary function test.  Obviously, many such studies were performed in the past showing that albuterol improves lung function while the placebo did not improve lung function.  The null hypothesis is now proven wrong as albuterol is shown to improve lung function while normal saline alone does not. 

Let us take another example here.  Many respiratory therapists have said that a majority of patients who receive an albuterol breathing treatment say they feel better after the treatment.  The hypothesis here is that a placebo will work just as well as albuterol in generating a perceived benefit.  This hypothesis was tested recently on 39 mild to moderate asthmatics

This calls for some more definitions. 
  • Perceived Response. This is when people who participate in the control group and received a placebo document that they feel better.  Of course we know it's not possible because they did not even receive the medicine. 
  • Placebo Response (Placebo Effect).  This is where a patient reports a perceived response from the placebo.  They think they received albuterol so they think they feel better.  The study showed that 50% of those in the placebo group reported a perceived response to the medicine. 
As I wrote regarding this study before: "This is interesting to say the least.  We know that albuterol really does make breathing easier in patients who are having actual bronchospasm.  However, evidence also suggests that giving albuterol to anyone who is short of breath may produce the placebo response.  So now you know why doctors treat all pulmonary diseases as asthma."

You also now know how clinical trials work. You also now understand how we must take the interpretations of clinical trials with a grain of salt, because they are not always accurate.  

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