Biologic plausibility is required for any thought process in medicine, whether it be for diagnosis or treatment or anywhere in between. This is much like face validity in research. It is requisite, but not sufficient for truth. You can’t hang your hat on either face validity or biologic plausibility.
In research biologic plausibility is some of the lowest level or evidence. That being the case, it is still a valuable tool in critical thinking. Does an idea pass the biologic plausibility test?
Much of the new and innovative ideas start out as a hypothesis that seems possible considering what we know about the body and how it works. This is a wonderful first step, no doubt. This thought process can lead you astray, or lead you home to a nice warm cozy theory.
It should be pointed out that this is extremely limited by the knowledge held by the individual and the field overall. The basic sciences, or even the advanced sciences of biology, physiology, anatomy and histology are the foundation. Understanding in these areas is required to make inferences as it relates to patient care.
We test the treatment techniques based on the foundation of these sciences to get outcomes. This is all well and good if the treatment is based off the sciences, off a ‘deep model’, off biologic plausibility. Again, biologic plausibility alone is not enough, but it must be there.
The more we understand about the physiology of the body and how the systems work and interact and heal and grow, etc the better we are at thinking about biologic plausibility. It allows us to critique ideas and be skeptical of approaches and at the same time develop new and exciting ideas, hypotheses and proposals.
The next time you are exposed to a new or even common treatment or thought process, give it some reflection. To the best of your knowledge, does it make sense? (Update: Allan Besselink PT, DipMDT wrote about this sort of thing on May 4th in the Three Legged Stool. Please continue this thought there…)
– Matt D