Types of Stem Cell Clinical Trials
Clinical trials come in many forms but the gold standard is commonly taken to be a randomized, placebo-controlled, double-blind clinical trial. What does this mean? Let’s take each aspect independently and explain its relevance.
What is Randomized?
Firstly, ‘randomized’ means that the researchers have done their utmost to ensure that the treatment group and the control group are randomly assigned and that there are no statistically significant differences between the groups such as having the treatment group largely male and the control group largely female, or having a higher average age in one than the other, or having all the controls as being from one particular ethnic group and the treatment group another. All of these factors can influence the outcome of studies as sex, age, and genetic differences found between different ethnic profiles can all contribute to altered physiological reactions to treatment. The larger the clinical trial the more likely randomization is to be successful at overcoming the influence of these differences. A trial of seven patients is unlikely to absorb one anomalous result that occurs due to the presence of poorly randomized participants.
What is Placebo Controlled?
Secondly, ‘placebo-controlled’ may be the most difficult aspect to good clinical trials as there are many schools of thought surrounding the use of placebos and their effectiveness. Many major drugs have been shown to be the same or little better than placebos during clinical trials at treating conditions such as depression and anxiety but are heavily marketed and prescribed anyway. Commonly, some patients may respond more to a placebo than others making them unsuitable for some highly sensitive clinical trials, others may show little response to a placebo and may in fact have somehow discovered the nature of the experiment thereby confounding the result anyway. This is a common problem with trials of alternative treatments such as massage, magnetic therapy, and talking cures which are very difficult to control with anything like a placebo. If a trial is conducted without a placebo then it makes it hard to discuss the outcome with any certainty as any effect (or non-effect) found may have occurred regardless of the treatment.
What is Double Blind?
Lastly, the term ‘double-blind’ may appear confusing but is basically a shorthand way of saying that a trial’s participants and the researchers are unaware of which treatment is being received or administered. For example, one group may be given a stem cell injection whilst another receives a simple saline solution; in a single-blind trial the subjects are unaware which they receive but the physician does know, in a double-blind trial the physician is also unaware. Clearly this requires a little more organization as care must be taken to document proceedings in order to avoid alerting either party to their assigned group. The purpose of double-blind trials is to eliminate the effect of researcher bias where those conducting the trial either consciously or subconsciously alter their behaviour towards the treatment and control groups to favor a specific outcome. Again, in some trials this is extremely difficult, if not impossible, to achieve, such as when using physical therapy, psychotherapy, or acupuncture for example.
There are many other aspects to clinical trials that could be discussed here, but the important thing is to examine the methodology of the research before jumping to conclusions about the relevance of a paper. Unfortunately, most discussion of research in the public domain centers on the abstract alone, or the outcome/results section of research papers which can often make unsubstantiated claims resting on shaky methodological foundations. Cynicism, remember.
Read on about: The Disadvantages of Clinical Trials
