Interpreting risk as evidence of causality: lessons learned from a legal case to determine medical malpractice.
Translating risk estimates derived from epidemiologic study into evidence of causality for a particular patient is problematic. The difficulty of this process is not unique to the medical context; rather, courts are also challenged with the task of using risk estimates to infer evidence of cause in particular cases. Thus, an examination of how this is done in a legal context might provide insight into when and how it is appropriate to use risk information as evidence of cause in a medical context. A careful study of the case of Goodman v. Viljoen, a medical malpractice suit litigated in the Ontario Superior Court of Justice in 2011, reveals different approaches to how risk information is used as or might be considered a substitute for evidence of causation, and the pitfalls associated with these approaches. Achieving statistical thresholds, specifically minimizing the probability of falsely rejecting the null hypothesis, and exceeding a relative risk of 2, plays a significant role in establishing causality of the particular in the legal setting. However, providing a reasonable explanation or establishing "biological plausibility" of the causal association also seems important, and (to some) may even take precedent over statistical thresholds for a given context.
Department of Medicine, Division of Emergency Medicine, McMaster University, Hamilton, Ontario, Canada.
Mathew
M
Mercuri
Institute for the History and Philosophy of Science and Technology, University of Toronto, Toronto, Ontario, Canada.
Brian S
BS
Baigrie
D000305:Adrenal Cortex Hormones / Q000009:adverse effects; D015984:Causality; D002547:Cerebral Palsy / Q000139:chemically induced; D004812:Epidemiologic Methods; D006801:Humans; D008318:Malpractice / Q000331:legislation & jurisprudence*; D009864:Ontario; D011336:Probability; D012306:Risk; D012720:Severity of Illness Index
D000305:Adrenal Cortex Hormones
Bayesian; causality; evidence; frequentist; risk