Bar News - October 20, 2006
Medical Malpractice Law: A New Look at the Cerebral Palsy Defense
By: Kevin M. Leach and Randolph J. Reis
It has long been known that lack of oxygen at birth causes brain damage and cerebral palsy. Despite this traditional view, a 1986 New England Journal of Medicine article by Karin Nelson, M.D., and Jonas Ellenberg, M.D., claimed that lack of oxygen at birth rarely causes cerebral palsy. The article has been regularly used in the defense of cerebral palsy cases to argue that the actions of medical practitioners around the time of labor and delivery rarely, if ever, caused cerebral palsy. However, a recent medical journal article exposes serious flaws in the Nelson/Ellenberg methodology and gives new hope to victims of this devastating birth injury.
“The Temporal Stage Fallacy: A Novel Statistical Fallacy in Medical Literature,” was published in July 2006 in the journal Medicine, Healthcare and Philosophy and authored by David Shier, associate professor and Philosophy Department chair at Washington State University, and J. Lee Tilson, a shareholder and medical malpractice attorney with the law firm Sommers, Schwartz, Silver & Schwartz in Southfield, Mich. The article contends that the complex form of statistical inference, which Nelson and Ellenberg use to reach the conclusion that medical care during labor and delivery does not cause cerebral palsy, is entirely fallacious. In particular, the authors examine the flawed statistical reasoning of Nelson and Ellenberg, and how their methodology leads to the erroneous statistical conclusion that prenatal events are not predictors of cerebral palsy. While this proposition has not yet been tested in the courts, it is noteworthy for its importance and potential impact on this important area of medical malpractice litigation.
Nelson and Ellenberg examined about 50,000 pregnancies from 1959-1966 and followed the children to age seven, where possible. Of the 45,000 cases for whom age-seven outcomes were known, 189 had cerebral palsy. The authors identified 25 risk factors that occur in significantly larger proportions of the 189 cases of cerebral palsy than in the general population of the study, and then divided them into two temporal stages. Stage one risk factors were those that occurred before labor, such as maternal seizures or bleeding (non-doctor risk factors). Stage two risk factors were those that occurred after labor, such as low fetal heart rate in labor and time elapsed before first crying (doctor-oriented risk factors). A baby having cerebral palsy with only stage two risk factors would indicate that cerebral palsy was caused by physician error. The Nelson and Ellenberg study, however, dramatically minimized the number of cerebral palsy cases caused by stage two risk factors through a statistical maneuvering of numbers and risk factor categories, which gave the impression that physician-induced cerebral palsy cases were very small in number.
The article emphasized that Nelson and Ellenberg failed to explain that more cases of cerebral palsy could be accounted for by stage two factors than by all other factors if the stage two factor cases were “new” cases, and not part of the grouping comprising a mixture of stage one and stage two factors. According to the new criticism, about one in five of all cases of cerebral palsy in the whole population are accounted for by late factors alone, but the Nelson and Ellenberg reasoning would force the reader to reject the late factors as an insignificant predictor by their method of logistical regression.
Other problems exist with the Nelson and Ellenberg study. For instance, it is impossible for the data to support general conclusions about how fetal distress affects outcome, because the fetal monitoring technology necessary to observe most types of fetal distress was not available at the hospital in question at the time the data were collected.
The new article is untested by the courts, but its analysis sheds much needed light on an area of medical malpractice that has confused courts and medical practitioners alike. Its initial pronouncement affirms the long-held belief that what happens in labor and delivery may determine whether a baby develops cerebral palsy.
Attorneys Randolph J. Reis and Kevin M. Leach, of Reis & Leach in Manchester, specialize in the practice areas of medical malpractice and personal injury cases. To contact them with your comments, e-mail email@example.com and firstname.lastname@example.org.