Opinion ID: 76908
Heading Depth: 1
Heading Rank: 4

Heading: Hashim Hakim, M.D.

Text: 93 Dr. Hakim is a medical doctor specializing in the practice of neurology; he is a clinician and not a medical researcher. He treated Plaintiff Thornburg and then saw the other three Plaintiffs on referral from Plaintiffs' counsel. He offered opinions at the Daubert hearing about the general toxicity of Metabolife and about its effects on the individual Plaintiffs, including that Metabolife caused ischemic strokes in three Plaintiffs and a heart attack in the other. 94 Hakim followed a methodology similar to O'Donnell's in determining the general toxicity of Metabolife. He relied in significant part on ephedrine's classification as a sympathomimetic, the PPA analogy, the Haller and Benowitz study, and the Hemorrhagic Stroke Project. To the degree to which Hakim and O'Donnell shared the same methodology about the general toxicity of Metabolife, their opinions share the same fate. Their opinions lack sufficient reliability to satisfy Daubert. Furthermore, like O'Donnell, Hakim failed to offer the type of evidence that could support his methodology, so his opinions are subject to the same conclusions that the court made about O'Donnell's opinions. The only question then about Hakim's testimony is whether the additional bases for his opinions, which O'Donnell's did not have, can overcome the defects in the methods they shared. The answer is no.
95 Hakim used the differential diagnosis approach to rule out all causes for Plaintiffs' injuries, except Metabolife 356. Under certain circumstances, circumstances that ensure reliability, this approach may offer an important component of a valid methodology. This approach, however, will not usually overcome the fundamental failure of laying a scientific groundwork for the general toxicity of the drug and that it can cause the harm a plaintiff suffered. 96 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. DORLAND'S ILLUSTRATED MEDICAL DICTIONARY 240, (Douglas M. 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 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 (Federal Judicial Center, 2d ed.2000). The etiology of a disease is the cause or origin of the disease, and in this case Plaintiffs allege that Metabolife is the etiology of their medical problems. 9 97 To support this theory, Hakim testified that he employed the differential diagnosis method. He took medical histories from Plaintiffs, examined them, and did some tests. After taking these steps, he concluded that he could rule out all the usual causes for Plaintiffs' injuries and therefore inferred that Metabolife caused the injuries. He assumed that Metabolife could cause these injuries using the same evidence offered by O'Donnell, the deficiencies of which the court has demonstrated at length. 98 A valid differential diagnosis, however, only satisfies a Daubert analysis if the expert can show the general toxicity of the drug by reliable methods. As the Court of Appeals for the Ninth Circuit explained: 99 The first step in the diagnostic process is to compile a comprehensive list of hypotheses that might explain the set of salient clinical findings under consideration.... The issue at this point in the process is which of the competing causes are generally capable of causing the patient's symptoms or mortality. Expert testimony that rules in a potential cause that is not so capable is unreliable.... It is important to realize that a fundamental assumption underlying [differential diagnosis] is that the final, suspected `cause' ... must actually be capable of causing the injury. 100 Clausen v. M/V NEW CARISSA, 339 F.3d 1049, 1057-58 (9th Cir.2003) (internal citations omitted). Thus, an expert does not establish the reliability of his techniques or the validity of his conclusions simply by claiming that he performed a differential diagnosis on a patient. As the Court of Appeals for the Fifth Circuit has explained: 101 No one doubts the utility of medical histories in general or the process by which doctors rule out some known causes of disease in order to finalize a diagnosis. But such general rules must ... be applied fact-specifically in each case. The underlying predicates of any cause-and-effect medical testimony are that medical science understands the physiological process by which a particular disease or syndrome develops and knows what factors cause the process to occur. Based on such predicate knowledge, it may then be possible to fasten legal liability for a person's disease or injury. 102 Black v. Food Lion, Inc., 171 F.3d 308, 314 (5th Cir.1999) (emphasis added). 103 Here, neither O'Donnell nor Hakim have offered a reliable explanation of the physiological process by which Metabolife causes heart attacks and ischemic strokes, i.e., establish general causation. Their PPA analogy does not show it. The medical articles do not explain it. In the absence of such a foundation for a differential diagnosis analysis, a differential diagnosis generally may not serve as a reliable basis for an expert opinion on causation in a toxic tort case.
104 In defending his methodology, Hakim also testified about case reports that he found in the medical literature. The case studies involve reports by doctors about patients whom the doctor suspects suffered a serious adverse reaction to ephedrine. These reports are anecdotal, meaning that they are based on descriptions of unmatched individual cases rather than on controlled studies. DORLAND'S, supra, at 76. Because they are anecdotal, case studies lack controls and thus do not provide as much information as controlled epidemiological studies do.... Causal attribution based on case studies must be regarded with caution. Henifin, supra, at 475. 105 We in fact discussed the value of case reports in Rider, explaining that: 106 Much of the plaintiffs' expert testimony relied on case reports in which patients suffered injuries subsequent to the ingestion of Parlodel. Although the court may rely on anecdotal evidence such as case reports, ... courts must consider that case reports are merely accounts of medical events. They reflect only reported data, not scientific methodology.... Some case reports do contain details of the treatment and differential diagnosis. Even these more detailed case reports, however, are not reliable enough, by themselves, to demonstrate the causal link the plaintiffs assert that they do because they report symptoms observed in a single patient in an uncontrolled context. They may rule out other potential causes of the effect, but they do not rule out the possibility that the effect manifested in the reported patient's case is simply idiosyncratic or the result of unknown confounding factors. As such, while they may support other proof of causation, case reports alone ordinarily cannot prove causation. 107 295 F.3d at 1199 (internal citations omitted). Simply stated, case reports raise questions; they do not answer them. 108 This analysis of the value and limitations of case reports is important in this case for two reasons. First, it explains something about Hakim's differential diagnosis method. If he had taken his findings and opinions about these four Plaintiffs and submitted them to a medical journal for publication, they would simply be case reports — anecdotal information, nothing more. Second, in light of all the other failures of proof on the reliability of their methods, Plaintiffs' experts cannot now redeem their opinions with this type of anecdotal evidence. They do not offer the underlying toxicological data in a scientifically reliable form to satisfy Daubert. Anecdotal evidence will not cure that failure. 109
110 Finally, in reaching his opinions that Metabolife 356 in fact caused each of the Plaintiff's injuries, Hakim claims to have used a challenge/de-challenge/re-challenge methodology. To explain this methodology during the Daubert hearing, Hakim testified that while treating Plaintiff Thornburg he noticed a pattern. When she took Metabolife 356, she had strokes, but when she did not take it, she did not have strokes until she started it again. In essence, the stroke occurred during the challenge stage when she took the drug. The de-challenge occurred when she came off the drug and did not have a stroke, and the re-challenge occurred when she started taking the drug again and had another ischemic event. But this theory has a serious flaw. 111 In April of 2000, Hakim decided that Metabolife had caused Thornburg's strokes and told her to stop taking it. In June of 2000, after being off Metabolife for two months, she had another ischemic event. In other words, according to his challenge/de-challenge/re-challenge theory, she had another ischemic event during the de-challenge phase. During the hearing, Hakim attempted to explain away that inconsistency by saying that the ischemic event during the de-challenge phase occurred because of the lingering effects of ephedrine. To bolster this opinion he resorted to another medical analogy — the analogy of alcohol causing liver damage. Nothing in the evidence, however, supports the dubious analogy that the ephedrine causes strokes and heart attacks like alcohol causes cirrhosis of the liver. 112 Furthermore, [t]he temporal connection between exposure to chemicals and an onset of symptoms, standing alone, is entitled to little weight in determining causation. Moore, 151 F.3d at 278. It is also subject to the problem of assuming what the witness is trying to prove. This pitfall will most likely arise when, as here, there are not scientific controls in place. 113 As this court explained in Rider , de-challenge/re-challenge tests are still case reports and do not purport to offer definitive conclusions as to causation. 295 F.3d at 1200. Their value is directly related to the degree of scientific control used in the testing. Because there were insufficient controls employed in Hakim's crude challenge/de-challenge/re-challenge methodology, and Hakim's own testimony established that Thornburg suffered ischemic events when she was not taking Metabolife 356, this methodology does not provide the necessary indicia of reliability to his final opinions on causation.
114 Again, like O'Donnell, Hakim failed to offer the type of evidence that could support the methodology he employed in reaching his opinions. Even considering the three additional methodologies he used, we must conclude that Hakim failed to rely upon reliable sources and data and that his overall methodology falls short of those standards otherwise utilized by experts testifying as to causation in a toxic tort case. It was therefore error to admit his testimony to establish general or individual causation at trial.