Relative Risk of Two in Medical Malpractice Cases

Counsel for plaintiffs and defendants in toxic tort cases are well aware of the need to show a sufficiently large relative risk, greater than two, to have sufficient evidence to satisfy the burden of proof on proximate causation between a known causal exposure and a specific plaintiff’s injury.  As Judge Jack Weinstein wrote 30 years ago, “[a] government administrative agency may regulate or prohibit the use of toxic substances through rulemaking, despite a very low probability of any causal relationship.  A court, in contrast, must observe the tort law requirement that a plaintiff establish a probability of more than 50% that the defendant’s action injured him. … This means that at least a two-fold increase in incidence of the disease attributable to Agent Orange exposure is required to permit recovery if epidemiological studies alone are relied upon.” In re Agent Orange Product Liab. Litig., 597 F. Supp. 740, 785, 836 (E.D.N.Y. 1984), aff’d 818 F.2d 145, 150-51 (2d Cir. 1987)(approving district court’s analysis), cert. denied sub nom. Pinkney v. Dow Chemical Co., 487 U.S. 1234 (1988).

In toxic tort cases, the risk ratio at issue allegedly results from a higher incidence of the disease in exposed persons compared to the incidence in unexposed persons.  A similar risk ratio issue occurs in medical malpractice cases when a healthcare provider negligently fails to administer a therapy, or fails to administer a therapy in a timely fashion, to the detriment of the plaintiff.  In instances in which the therapy is almost always efficacious, the risk ratio of a bad patient outcome will be very high, and the corresponding probability that the bad outcome would have been avoided by proper or timely therapy will be close to 100 percent.  On the other hand, for some therapies, even timely administration is efficacious in a limited number of cases, less often than the 50-plus percent of cases that would support a proximate cause opinion between the allegedly negligent failure to administer therapy and the patient’s bad health outcome.

Unfortunately, the relative risk issue goes unlitigated in many cases, in New York and elsewhere. One recurring malpractice claim involves the alleged failure to administer clot-busting drugs to ischemic stroke patients.  One such drug, tissue plasminogen activator (t-PA), which was approved by the Food and Drug Administration in 1996, can substantially reduce brain damage if administered within three hours of stroke onset.  Even if administered within the crucial therapeutic time window, however, t-PA will benefit only about 30 percent of patients, and there is no medical “fingerprint”that identifies who has benefitted from the t-PA. In Samaan v. St. Joseph Hospital, 670 F.3d 21 (1st Cir. 2012), the First Circuit acted on its gatekeeping responsibilities to perscrutate the risk evidence and found that it fell short of what is required by Federal Rule of Evidence 702, and the “more likely than not” standard for civil cases. See also Smith v. Bubak, 643 F.3d 1137, 1141–42 (8th Cir.2011) (rejecting relative benefit testimony and suggesting in dictum that absolute benefit “is the measure of a drug’s overall effectiveness”); Young v. Mem’l Hermann Hosp. Sys., 573 F.3d 233, 236 (5th Cir.2009) (holding that Texas law requires a doubling of the relative risk of an adverse outcome to prove causation), cert. denied, ___ U.S. ___, 130 S.Ct. 1512 (2010).

Samaan and the cases cited by the First Circuit are hardly unique; the size of the relative risk issue has helped the defense prevail in other t-PA and similar malpractice cases around the country. Kava v. Peters, 450 Fed.Appx. 470, 478-79 (6th Cir. 2011) (affirming summary judgment for defendants when plaintiffs expert witnesses failed to provide clear testimony that plaintiff specific condition would have been improved by timely administration of therapy); Bonesmo v. The Nemours Foundation, 253 F.Supp. 2d 801, 809 (D.Del. 2003); Joshi v. Providence Health System of Oregon Corp., 342 Or. 152, 156, 149 P. 3d 1164, 1166 (2006) (affirming directed verdict for defendants when expert witness testified that he could not state, to a reasonable degree of medical probability, beyond 30%, that administering t-PA, or other anti-coagulant would have changed the outcome and prevented death); Ensink v. Mecosta County Gen. Hosp., 262 Mich.App. 518, 687 N.W.2d 143 (Mich.App. 2004) (affirming summary judgment for hospital and physicians when patient could not greater than 50% probability of obtaining a better result had emergency physician administered t-PA within three hours of stroke symptoms); Merriam v. Wanger, 757 A.2d 778, 2000 Me. 159 (2000) (reversing judgment on jury verdict for plaintiff on grounds that plaintiff failed to show that defendant failure to act were, more likely than not, a cause of harm). In Michigan, the holding of the t-PA and similar medical malpractice cases has been codified by statute:

“In an action alleging medical malpractice, the plaintiff has the burden of proving that he or she suffered an injury that more probably than not was proximately caused by the negligence of the defendant or defendants. In an action alleging medical malpractice, the plaintiff cannot recover for loss of an opportunity to survive or an opportunity to achieve a better result unless the opportunity was greater than 50%.”

Mich. Comp. Laws § 600.2912a(2) (2009).  But see O’Neal v. St. John Hosp. & Med. Ctr., 487 Mich. 485, 791 N.W.2d 853 (Mich. 2010) (affirming denial of summary judgment when failure to administer therapy (not t-PA) in a timely fashion more than doubled the risk of stroke). In one unpublished Kentucky case, involving t-PA, the court seemed to acknowledge the general principle, but became confused as to whether 30 percent, was a reasonable probability. Lake Cumberland, LLC v. Dishman, 2007 WL 1229432, *5 (Ky. Ct. App. 2007) (unpublished) (citing without critical discussion an apparently innumerate opinion of expert witness Dr. Lawson Bernstein).

Despite the success of medical malpratice defense counsel in litigating dispositive motions in t-PA cases, the issue seems to go unnoticed in New York cases. For instance, in Gyani v. Great Neck Medical Group, a stroke victim sued on various allegations of medical malpractice, including failure to administer t-PA.   N.Y. S.Ct. for Nassau Cty, 2011 WL 1430037 (April 4, 2011). The trial court denied summary judgment on proximate cause grounds, and noted that

“[t]he plaintiffs’ expert ultimately opines that the failure to administer t-PA allowed Gyani’s stroke to go untreated and progress to the point of her being locked-in permanently which would not have happened had t-PA been administered.”

From the court’s opinion, it would appear that defense counsel never pressed beyond this conclusory opinion, devoid of quantified relative risk. Behind the curtain of “ultimate” opinion is an expert without a meaningful basis for his opinion.  It is time to pull the curtain.

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