A federal court recently granted summary judgment against Illinois plaintiffs who alleged that the blood clotting drug Trasylol caused the husband's kidney failure. See Miller v. Bayer Corp., No. 09-81262 (S.D. Fla., 7/3/13). (One of the remaining cases in the MDL.)

Plaintiff underwent double coronary artery bypass graft and aortic valve replacement surgery. At the time of his surgery, he was a former smoker with a lengthy medical history which included hypertension, hyper-lipidemia, chronic renal insufficiency, and coronary artery disease. The surgeon used Trasylol during the surgery to help control the bleeding. Plaintiff had signed an informed consent which enumerated the potential risks and benefits of cardiac surgery including infection, bleeding, heart damage, stroke, kidney damage, or even death.

After his surgery, Mr. Miller experienced a small acute left hemispheric stroke;  he also experienced a transient rise in his serum creatinine which peaked at 2.4 on postoperative day eight. (Creatinine is a waste product formed by the breakdown of a substance important for converting food into energy; if the kidneys are damaged and cannot function normally, the amount creatinine in the blood can increase.)

Plaintiffs sued for personal injuries allegedly caused by the use of the drug during surgery. Defendant moved for summary judgment as to each of Plaintiffs’ claims, asserting (1) under Illinois law, causation is an element of each of Plaintiff’s claims, and Plaintiffs’ expert’s causation testimony was inadmissible; (2) even if Plaintiffs’ expert’s testimony were admissible, their apparent claims failed because they were seeking damages for Mr. Miller’s stroke, and their expert was not qualified to render an opinion as to the cause of the stroke. Plaintiffs responded that despite some confusion, ultimately they were not seeking damages due to Mr. Miller’s stroke, but for his “acute renal failure”; that the expert was qualified to testify; and “the temporal connection" between Mr. Miller’s acute renal failure and the injection of Trasylol, together with the alleged absence of renal issues prior to the surgery and the fact that Trasylol is supposedly a nephrotoxic agent, were sufficient to support an opinion that Trasylol was a substantial contributing factor in causing Mr. Miller’s injuries. 

The court noted that expert medical opinion evidence is usually required to show the cause of an injury or disease because the medical effect on the human system of the infliction of injuries is generally not within the sphere of the “common knowledge of the lay person.” See Fuesting v. Zimmer, Inc., 421 F.3d 528, 536 (7th Cir. 2005), rev’d on other grounds by Fuesting v. Zimmer, Inc., 448 F.3d 936 (7th Cir. 2006); Ancho v. Pentek Corp., 157 F.3d 512, 519 (7th Cir. 1998); Goffman v. Gross, 59 F.3d 668, 672 (7th Cir. 1995); Wallace v. McGlothan, 606 F.3d 410, 420 (7th Cir. 2010). Claims for negligence, strict liability, breach of express warranty, breach of implied warranty, fraudulent misrepresentation, fraudulent concealment, violation of consumer protection statutes, wrongful death, and loss of companionship, as well as a survival claim  all will fail where a plaintiff has no evidence of specific causation. See Schrott v. Bristol-Myers Squibb Co., 403 F.3d 940 (7th Cir. 2005). To avoid summary judgment, the Plaintiffs therefore must come forward with evidence that would allow a reasonable jury to find causation. Causation must be established by provable facts; it cannot be based on guess, conjecture, surmise, possibility, speculation, or mere allegation. 

In summary, plaintiffs' expert opined that in all medical certainty causation of Mr. Miller’s alleged renal failure was likely multifactorial, with significant contributing factors including cardiopulmonary bypass surgery, associated blood pressure fluctuations, and the use of the medication.  The drug, he said, "in all medical certainty, was a significant contributing factor.” Additionally  he opined that the physicians caring for Mr. Miller “would not have used” this drug had they been aware of the association of mortality and acute kidney injury.  Plaintiffs argued the expert had conducted a legally sufficient differential diagnosis which emphasized the  "temporal connection between Mr. Miller’s acute renal failure and the injection of Trasylol, together with the absence of renal disease or issues prior to the surgery.

This court falls in the camp of those who conclude that a differential diagnosis, properly performed, constitutes a reliable methodology for determining medical causation under Daubert. See Guinn v. Astrazeneca Pharms. LP, 602 F.3d 145, 153 (11th Cir. 2010); Ervin v. Johnson & Johnson, Inc., 492 F.3d 901, 904 (7th Cir. 2007).  Readers will recall that we have explained how plaintiffs have mis-used the notion of differential diagnosis, jumping from a medical method to figure out what disease a patient has to a legal method to figure out why the patient has the disease.  In any event, the court noted that 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.  Instead, a court must examine whether the expert correctly applied the differential diagnosis methodology. 

As applied in several courts, the method requires an expert to rule in all the potential causes of a patient’s ailment and then by systematically ruling out causes that would not apply to the patient, the physician arrives at what is the likely cause of the ailment. Westberry v. Gislaved Gummi AB, 178 F.3d 257, 262 (4th Cir. 1999)).  Plaintiff experts routinely make a couple mistakes:  Expert testimony that rules in a potential cause of a patient’s symptoms that is not so capable is unreliable.  At the rule out step, the expert must at least consider the other causes that could have given rise to Plaintiffs’ injury.  Courts vary on whether the expert must rule out all possible alternative causes, or the most likely ones, or at least consider other factors that could have been the sole cause of the plaintiff's injury.  A differential diagnosis that fails to take serious account of other potential causes may be so lacking that it cannot provide a reliable basis for an opinion on causation.  And an expert must provide a reasonable explanation as to why he or she has concluded that any alternative cause suggested by the defense was not the sole cause of the plaintiff’s injury.

The court then noted that  a temporal connection between exposure to chemicals and an onset of symptoms, standing alone, is entitled to little weight in determining causation. See McClain v. Metabolife Int’l, Inc., 401 F.3d 1233, 1254 (11th Cir. 2005); Happel v. Walmart Stores, Inc., 602 F.3d 820 (7th Cir. 2010).  Temporal proximity is especially unreliable where conditions independent of exposure to the drug could have been the sole cause of the plaintiff’s injury, and the expert fails to explain the relative contribution of the drug to the injury.  Here, one flaw in the expert's methodology was his failure to account for or appropriately address numerous risk factors at both the rule in and rule out stage., factors which either alone or in combination could explain Mr. Miller’s alleged renal injury. These factors include, but were not limited to: pressure stabilizing medications; extended pre-surgical and post-operative hypertension; and pre-surgical chronic renal failure. Even to those factors which the expert did rule in, he either gave them short shrift at the rule-out stage, or dismissed them without discussion.  In neither his report nor deposition did the expert provide any explanation for why he concluded that Mr. Miller’s various risk factors other than exposure to Trasylol were not the sole cause of his injuries. In fact, during his deposition, he conceded several additional risk factors for Mr. Miller that he had failed to consider in rendering his opinion, and further testified that many of those risk factors, either alone or in concert, could have caused Mr. Miller’s transient creatinine rise. He was forced to admit that Mr. Miller, without Trasylol, “could have had the same postoperative course.”

Thus there was no way to determine that one factor had more of an effect than the others. That led plaintiff to argue that Trasylol somehow tipped the scales causing his renal injury (the so-called straw that broke the camel's back).  But after sorting through these opinions and the Plaintiffs’ response to Defendants’ Motion, the court found that exclusion of the expert was warranted because of the absence of a reliable methodology, the failure to provide a plausible explanation for why he concluded that Mr. Miller’s various risk factors other than exposure to Trasylol were not the sole cause of his renal injury. Under Illinois law, a party cannot create a genuine issue of fact merely by presenting an expert witness who is willing to express an unsupported opinion that favors the party’s position. See Lewis v. CITGO Petroleum Corp, 561 F.3d 698, 705 (7th Cir. 2009).