I recently escalated my blogging in which I discuss the difference between differential diagnosis and causation. I have done this because this issue continues to confuse the courts and counsel as a recent article in a DRI on-line publication indicates. That piece, “Differential Diagnosis - The Unknown Matters: Admissibility of Differential Diagnosis Opinions in the Context of Idiopathic Conditions” discusses decisions in which “idiopathic” (meaning no known cause) has been considered, at times, a proper endpoint for a differential diagnosis. That is flat out wrong since “idiopathic” has nothing whatsoever to do with a diagnosis or with differential diagnosis.
In this piece, Mr. Kerner discusses recent court decisions focusing primarily on the use of “differential diagnosis” as a means of including or excluding “idiopathic” (or, unknown causes). Certain aspects of these cases demand further discussion. First of all, “idiopathic” has nothing to do with differential diagnosis. Rather, it has to do with causation assessment, what Mr. Kerner properly termed “differential etiology.” That term also connotes a process which follows, but is not the same as the differential diagnostic process. The cases discussed included a number of diseases: AML (acute myelogenous leukemia) , syringomyelia, Autism Spectrum Disorder (ASD), and breast cancer.
In each of these cases, the court considered, and ruled varyingly, whether a “differential diagnosis” of “idiopathic” should or should not have been considered. The fact is that each of those named disorders above is the end of the road for the differential diagnostic methodology. In other words, the patient presented with certain signs and symptoms, differential diagnoses (potential diagnoses which could explain the symptoms or signs evident in the patient) were considered, studies were done and the diagnosis was one of those disease entities. Those diagnoses end the differential diagnostic process. Whether or not the disease was idiopathic arises from a totally separate and distinct assessment – causation.
That step, “causation assessment” or “differential, etiology” asks and considers what possible causes (external or internal factors) led to that diagnosed condition.
It seems to me that the courts are frequently getting this standard medical methodology wrong. Therefore, it is time to have experts testify specifically to the nature of differential diagnosis and its outcome – i.e., the diagnosed disease or disorder – and the nature of causation assessment – i.e., the factor(s) which led to that disorder – and its outcome. Otherwise, medical experts are being permitted to misuse the methodology of medicine – the differential diagnostic process – to arrive at a causal conclusion, thereby misleading the courts. Click here to see my diagram of these two processes to demonstrate their distinct characteristics and methodologies.
Lastly, I believe that this topic needs to continue to be explained and I would invite anyone who is interested to contact me about co-writing a scholarly legal (Law Review) article on this topic. I can be reached at 301-519-0300 or by email at email@example.com.