Differential diagnosis: Scientific methodology required to ‘rule out’ causes


In the case of United States v Bailey [2015 U.S. Dist. LEXIS 97288], the district court rejected the expert witness of the plaintiff on the ground that the testimony had failed to meet the requisite standard required under Rule 702 of the Federal Rules of Evidence. The Court used the differential diagnosis test which the expert medical testimony used by the plaintiff failed to satisfy. With the expert opinion being excluded, the Court allowed the defendants’ motion for a summary dismissal.


This case had been brought by the plaintiff against the United States military for being negligent in causing the death of her fiancé, Wilsey. Wilsey had been training with a combination of cardiovascular exercise, weight loss pills, purging and dieting to be able to meet the requirements that the United States military had in place for new recruits. A few months after his regimen started and showed signs of progress (allegedly under the supervision of the recruiting officer of the recruiting base at Ohio), the plaintiff found Wilsey unresponsive at his home. Upon being taken to a hospital, Wilsey was pronounced dead. No postmortem autopsy was conducted upon the request of the plaintiff. To prove negligence under Ohio law, the plaintiff needed to show that the United States military owed a duty of care and that duty was breached. In this case, the plaintiff was unable to prove either. She failed to prove that the cause of the death of her fiancé could be proximately linked to the negligent actions of the defendants. To prove causation, the plaintiff required the expert testimony to satisfy the requirements of Rule 702 which it failed to do.


The Court analyzed the testimony of Dr. Noftz (the expert medical witness offered by the plaintiff) to decide whether there was a link between the Wilsey’s approved regimen and the subsequent acute cardiac dysrhythmia that he suffered. Since the link between the two is such that would not be possible for a layperson to make, the case would hinge on the expert testimony that was presented by the plaintiff. The test that was laid down to assess medical causation testimony is the differential diagnosis test, an application of the Daubert test. This test was discussed in Best v. Lowe’s Home Centers, Inc. [563 F.3d 171,179 (6th Cir. 2009)]. In that case it was laid down that the medical expert had to (a) judge the nature of the injury caused as best as possible (b) using reliable methodology rule “in” a cause of injury which seems most probable (c) using similar scientific methodology to rule “out” other possible causes.

Dr. Noftz failed in his assessment to rule out other causes of cardiac arrest. Further, according to his own testimony, it was not possible for a definitive evaluation without a postmortem report or any data on Wilsey’s activities forty eight hours before his demise. Using the coroner’s report, medical reports and death certificate electrolyte imbalance can be ruled ‘in’ as a cause as argued by the plaintiff. However, Dr. Nortz failed to show how he could rule out other non-dietary causes of cardiac arrest using the evidence at his disposal. Thus, the Court held that the expert testimony had failed to satisfy the differential diagnosis test [Tamraz v. Lincoln Electric Co., 620F.3d 665 (6th Cir. 2010)] as laid down in a series of cases. Thus the expert testimony of Dr. Noftz was excluded and the suit was summarily dismissed.