ABSTRACT
While medical experts often opine about causation in medical malpractice lawsuits, mapping the medical literature onto the probabilistic ‘more likely than not’ legal causation standard sometimes goes beyond medical expertise. In many medical malpractice applications, experts cannot utilize the logic of differential etiology and general and specific causation that are common in toxic tort cases, leaving experts without a principled framework for translating from the medical literature onto the legal causation standard. As a result, experts have used different – and sometimes incorrect – approaches to this translation. This is particularly true in stroke litigation, where parties, experts, and sometimes courts have struggled with whether the existing medical research is sufficient to prove legal causation. Using a counterfactual framework, this Essay illustrates the relationship between common epidemiologic effect measures in the medical literature and the probability of legal causation. This Essay also highlights common missteps made by experts, using stroke litigation as an exemplar, and provides guidance for using medical literature to inform causation opinions in medical malpractice litigation.
Hund, Lauren, Moving from Medical Risk to Medicolegal Causation: An Exemplar from Stroke tPA Litigation (February 2, 2026).
I read with great interest and was involved as an expert in at least one of your cited cases–Maxey vs Bosworth. The judge ruled against the Zivin paper, and I was only recently made aware of this. In looking at expert testimony, some is completely incorrect and some errors in testimony resulted from neurologists testifying against the statistical approach, which they didn’t understand. No statistician was involved. Stroke is a very complex disease, as the brain has thousands of functions and each stroke is different. Devising a measurement tool that allows us to determine causation is basically impossible, and all stroke trials are scored in large part by non physicians. On the other hand those of who treated stroke for 20 years before tPA, making ourselves familiar with the rarity of improvement in the first hour in the ED, could only be stunned as we watch patients begin to move a limb or talk–absolutely compelling. I would love to review with you the specific testimony about the Zivin papers in your cases. I am currently preparing a paper on this specific topic for review. I am also very concened the the journal which published the Zivin paper almost certainly had a statistician review the paper, but none of the legal challenges to the Zivin paper included a statistician.