15 Years Since Creanga v. Jardal Validated Medical Opinions Based on “Differential Diagnosis”

On this date in 2005, the Supreme Court decided Creanga v. Jardal, 185 N.J. 345 (2005). In a unanimous opinion by Justice Zazzali, the Court reversed the rulings of the Law and Appellate Division that excluded, as a net opinion, evidence given by plaintiff’s expert, Dr. Zarghami, based on “differential diagnosis.”

Here is how Justice Zazzali summarized the case at the start of his opinion:

“Plaintiff Mihaela Creanga claims that an automobile accident was the proximate cause of her premature labor and the resultant death of one of her twins. In support of her claim, she offered the expert opinion of her treating physician who stated that the accident caused the miscarriage. He based that opinion on a differential diagnosis of plaintiff’s injury, that is, he identified the accident as the proximate cause of plaintiff’s injury after the elimination of other alternatives. In reaching his conclusion, the physician considered various factors including his treatment of plaintiff before, during, and after the premature labor and plaintiff’s medical records.”

Because the only issue before the Supreme Court was the reliability of Dr. Zarghami’s methodology, it became necessary to determine “whether differential diagnosis is admissible as a general matter, and, specifically, whether Dr. Zarghami’s differential diagnosis is admissible.” If the answers were both affirmative, the final inquiry was whether the doctor’s testimony was a net opinion.

Justice Zazzali cited several definitions of ‘differential diagnosis.” One of those was “a patient-specific process of elimination that medical practitioners use to identify the ‘most likely’ cause of a set of signs and symptoms from a list of possible causes.” The process works by first “ruling in” all “plausible causes” that are “generally capable of causing the patient’s symptoms or mortality” (emphasis in original). Then, the expert “must rule out those causes that did not produce the patient’s condition by engaging in a process of elimination, eliminating hypotheses on the basis of a continuing examination of the evidence so as to reach a conclusion as to the most likely cause of the findings in that particular case,” using “sufficient diagnostic techniques to have good grounds for his or her conclusion.”

Justice Zazzali observed that differential diagnosis had been accepted in New Jersey toxic tort cases, in decisions of other states, and by federal courts. “Accordingly, because of the widespread acceptance of differential diagnosis in the medical community, the recognition of the technique in state and federal courts, and its compatibility with our rules of evidence and prior case law, we conclude that a trial court may admit an expert’s differential diagnosis into evidence.”

But it was not enough for the expert to utter the words “differential diagnosis.” It was necessary to show that he had properly conducted that procedure. The Court found that Dr. Zarghami had done so here.

Finally, Justice Zazzali disagreed that Dr. Zarghami had rendered a net opinion. He had given the “why and wherefore” of his conclusion, not just a bare opinion.

Nor was the presence of inconsistencies in his opinion grounds for excluding it. “To be sure, there may be inconsistencies in Dr. Zarghami’s testimony, but those inconsistencies go to the weight to be given by the fact-finder to Dr. Zarghami’s testimony, and not to its admissibility. In this context, it is the role of the jury–and not of the court on summary judgment–to consider any inconsistencies when it decides how much weight to assign to his testimony. In this appeal, the alleged inconsistencies do not render Dr. Zarghami’s opinion inadmissible.”

Differential diagnosis became best-known to the public through the television show “House,” which ran from 2004-12. In that same window, the Creanga case brought differential diagnosis to the fore in the real world, not just the television world.