Opinion ID: 1208799
Heading Depth: 1
Heading Rank: 4

Heading: The Testimony of Dr. Peter Gregor

Text: In the case before us, the majority holds that Dr. Gregor was both qualified to render an expert opinion regarding causation and that his opinion was reliable because it was formed through a scientific method called differential diagnosis. The majority, in adopting Syllabus Point 5, concludes that a medical opinion based upon a properly performed differential diagnosis is sufficiently valid to satisfy the reliability prong of Rule 702. I do not agree with the majority's holding, particularly because the majority confuses the terms, differential diagnosis and differential etiology. I believe Dr. Gregor simply was not qualified to render an expert opinion on the cause of the gastroenteritis from which Mr. San Francisco was suffering, and any opinions in this regard were unequivocally unreliable. While Dr. Gregor, a cardiologist, may have been qualified to testify as to the indications, diagnosis, and treatment of food poisoning since he evaluated Mr. San Francisco in the emergency room, I believe that he required more specialized knowledge and information in order to testify regarding the issue of external causation. Dr. Gregor admitted that, as a cardiologist, he was not an expert on etiology in foodborne illness. Despite this, the majority relies upon Westberry v. Gislaved Gummi AB, 178 F.3d 257, 262 (4th Cir.1999), a case recognizing that a differential diagnosis, or differential etiology, is a standard scientific technique of identifying the cause of the medical problem by eliminating the likely causes until the most probable one is isolated sufficient to meet the requirement of Rule 702. I agree with the contention set forth by the appellees, that the terms differential diagnosis and differential etiology are two separate conceptsa differential diagnosis being a medical process and differential etiology being a legal concept.
The majority defines the term differential diagnosis as a methodology employed by medical practitioners to determine by a process of elimination both the disease or condition from which a patient is suffering and the internal or external cause of the disease or condition. The majority, like many courts, have used the term in a way that differs from its dictionary definition and from its usage in the medical community. [5] As recognized by the Eleventh Circuit Court of Appeals in McClain v. Metabolife Intern., Inc., 401 F.3d 1233, 1252 (11th Cir. 2005): Differential diagnosis involves the determination of which one of two or more diseases or conditions a patient is suffering from, by systematically comparing and contrasting their clinical findings. BORLAND'S ILLUSTRATED MEDICAL DICTIONARY 240, (Douglas Anderson et al. ed., 29th ed.2000). This leads to the diagnosis of the patient's condition, not necessarily the cause of that condition. The more precise but rarely used term [for determining the cause of a condition] is differential etiology, which is a term used on occasion by expert witnesses or courts to describe the investigation and reasoning that leads to the determination of external causation, sometimes more specifically described by the witness or court as a process of identifying external causes by a process of elimination. See Mary Sue Henifin et al., Reference Guide on Medical Testimony, in REFERENCE MANUAL ON SCIENTIFIC EVIDENCE 439, 481 (Fed.Jud.Ctr.2d ed.2000). At one level, the confusion is terminology in only semantic. . . . [h]owever, at another level the confusion can mislead. 2 Faigman, Modern Scientific Evidence at § 20-1.1 at 541. The danger is that, in conflating these two concepts, a physician could, as here, be permitted to testify beyond his or her areas of expertise. [6] While the two methodologies may employ a similar process, that of deduction or elimination, the differences are more than nomenclature, they are substantive for [v]ery different skill sets are usually involved in these two determinations, [7] that of diagnosing a patient's condition and that of identifying the external cause of the condition. As one author has explained: The distinction between differential diagnosis and differential etiology may seem subtle, but it is actually quite profound. Although doctors receive substantial training on formulating a differential diagnosis, they receive very little training, if any, on how to conduct a differential etiology. Furthermore, doctors rarely perform differential etiology when treating patients. . . . If an elderly patient were to tell a doctor that she had shortness of breath, the doctor may use a differential diagnosis to eliminate heart disease, anemia, lung fibrosis, and emphysema as possible causes. [The doctor] may then conclude that the most likely cause of the shortness of breath is chronic bronchitis, an internal disease. The physician would rarely analyze external factors such as workplace conditions in practice, but patients often call in doctors to do so in litigation. Thus, if a court were to mistake a differential etiology analysis for a differential diagnosis analysis, the court could errantly overemphasize the physicians's qualification to give competent and relevant testimony . . . In contrast to a differential diagnosis, evaluating external causation is a process in which most physicians are inexperienced and uncomfortable. Spechler, supra, note 6, at 743-746. [8] Differential diagnosis involves a rigorous exercise in ruling out possible diagnoses and ruling in the most likely diagnosis. Differential etiology involves ruling out other possible external causes for the diagnosed condition and ruling in the mostly likely external cause. As one commentator has observed, suppose that the expert purported to rest the opinion solely or primarily on the timing the fact that the plaintiff contacted the illness shortly after exposure to the alleged causal factor.[ [9] ] There is a grave doubt whether such an opinion would even be admissible. The opponent would have two cogent arguments. Under amended Federal Rule 702(3), the opponent would urge that the expert has not followed accepted methodology in conducting the analysis. The opponent would have an even stronger argument that the opinion is inadmissible because it is not based upon sufficient facts or data. Inferring causation from the timing is an example of the classical logical fallacy, post hoc, ergo propter hoc  it is illogical to infer that event A caused condition B because A preceded B. Even if the judge generously admitted a differential etiology opinion with such a skimpy basis, that opinion certainly would not be adequate to support a finding of specific causation. Imwinkelried, supra, note 6, at 416-17 (internal footnotes omitted). [10]
In the case at hand, a reliable and properly conducted differential diagnosis of Mr. San Francisco's symptoms required Dr. Gregor to rule in or out pre-existing gastrointestinal problems, alcohol use, peptic ulcer disease, diverticulitis, and foodborne illness. A reliable and properly conducted differential etiology to determine an external cause of the diagnosed condition (foodborne illness) required Dr. Gregor to rule in or rule out a ham, home-cooked chicken strips, homemade beef stew, pork chops, potato salads, a Wendy's hamburger, and other items that Mr. San Francisco had eaten within the week preceding the onset of his symptoms as the cause of his symptoms. The appellees in their brief represent that Dr. Gregor in his deposition acknowledged that he was not aware of Mr. San Francisco's having eaten these foods, except for the Wendy's hamburger. How is it possible for a physician to rule out other possible foods as the cause of Mr. San Francisco's symptoms if he was unaware of what other foods had been eaten by Mr. San Francisco within the typical incubation period for E. Coli to develop into a verotoxin? Moreover, how could Dr. Gregor reliably conclude that the Wendy's hamburger was the cause of his diagnosis of Mr. San Francisco's symptoms if he did not consider that no other patrons of that same Wendy's restaurant had reported any illness from eating a Wendy's hamburger on the day that Mr. San Francisco developed his symptoms, including Mr. San Francisco's wife who ate a portion of her own allegedly underdone hamburger? The appellants represent that Dr. Gregor's testimony as to the diagnosis and causation of Mr. San Francisco's illness has a sufficient factual background based on Dr. Gregor's observations and treatment of the patient and that his testimony will assist the trier of fact. Observations and treatment as the basis for making a diagnosis and identifying a cause of a diagnosed condition fall far short of demonstrating that Dr. Gregor made a properly conducted and reliable differential diagnosis of Mr. San Francisco's symptoms and made a properly conducted and reliable differential etiology of the cause of Mr. San Francisco's symptoms. The appellants further contend: that Dr. Gregor noted that Mr. San Francisco vomited 1.8 liters while in the emergency room, which he considered very substantial; that after considering the patient's history, Dr. Gregor was able to rule out other causes for the illness by performing a differential diagnosis which included his findings of no preexisting gastrointestinal problems, no alcohol use, no peptic ulcer disease and no history of diverticulitis; that after a thorough clinical examination, Dr. Gregor was able to reach a diagnosis and opinion as to causation, based on his examination of the patient and his symptoms, the patient's medical history, his recent travel history and his food intake history [11] ; and that each of the items was specifically considered. In so doing Dr. Gregor testified, [i]f you ask me, do I think a hamburger at a restaurant with diarrhea, vomiting and fluid loss shortly thereafter was the cause of the hospitalization, I would say yes . . . It was the hamburger. The appellants' arguments are for the most part conclusory and do not show the procedures followed by Dr. Gregor in making a differential diagnosis of Mr. San Francisco's condition or in making a differential etiology of the cause of the condition. They only represent that Dr. Gregor reached a diagnosis and opinion as to causation, based on his examination of the patient and his symptoms, the patient's medical history, his recent travel history and his food intake history. An examination of the patient's symptoms and various histories does not amount to the formation of a reliable opinion as to diagnosis or the cause of the diagnosis based upon a properly conducted differential diagnosis and differential etiology. Moreover, Dr. Gregor in his testimony acknowledged that his identification of the cause of Mr. San Francisco's symptoms as being the Wendy's hamburger was because of the temporal relationship between the eating of the hamburger by Mr. San Francisco and his onset of the symptoms. As Imwinkelried noted in his Baylor Law Review article [i]nferring causation from the timing is an example of the classical logical fallacy, post hoc, ergo propter hoc it is illogical to infer that event A caused condition B simply because A preceded B. Imwinkelried, supra note 6, at 417 The majority opinion concludes that a differential diagnosis is a tested methodology, has been subject to peer review/publication, does not frequently lead to incorrect results, and is generally accepted in the medical community. Majority opin., p. ___ W.Va. ___, 656 S.E.2d 498 quoting Turner v. Iowa Fire Equip. Co., 229 F.3d 1202, 1208 (8th Cir. 2000). The majority further concludes that a medical opinion based upon a properly conducted differential diagnosis is sufficiently valid to satisfy the reliability prong of the Rule 702 inquiry under Dauber[t]/Wilt. Majority opin., p. ___ W.Va. ____, 656 S.E.2d 499. The majority opinion notably does not disclose why it believes that Dr. Gregor properly conducted a differential diagnosis in both diagnosing Mr. San Francisco's condition and determining the cause of his condition. For all of the above reasons, I would exclude the testimony of Dr. Gregor on the basis that it is unreliable. Because it is evident that a differential diagnosis is not relevant to the issue of causation, summary judgment was appropriate in this case. [12]