Diagnosis by medical expert witness not the same as causation testimony: Oklahoma District Court

Commenting on the difference between diagnosis and etiology, the Oklahoma District Court recently ruled that although a medical expert witness might have sufficient qualification to testify about the treatment or diagnosis of a particular ailment, it does not necessarily qualify him to testify as an expert as to the cause of the disease.

Details of the case

Plaintiff Helen Shrum filed this lawsuit against Defendant Novartis Pharmaceuticals Corporation, alleging that the Defendant’s drugs named Aredia and Zometa had caused her to develop osteonecrosis of the jaw (ONJ). Plaintiff designated one of her treating oral surgeons as a case-specific medical expert witness to testify as to causation. Defendant moved to exclude the expert’s causation testimony on the grounds that he lacked the appropriate qualifications and did not use a reliable methodology in concluding that Aredia and Zometa were the cause of Plaintiff’s ONJ.

Expert witness or Fact witness?

Firstly the Court noted that this case was unusual in that the purported expert testified at deposition that he had not actually been retained by Plaintiff as an expert witness, understood that he was merely a fact witness, and did not consider himself an expert on ONJ or bisphosphonate drugs like Aredia or Zometa.

Despite this testimony, Plaintiff insisted that the expert was qualified to give case-specific opinion testimony on the cause of her ONJ. As support, Plaintiff pointed to the expert’s experience as a board certified oral and maxillofacial surgeon, his clinical practice, his treatment of other patients with bisphosphonate induced ONJ, his review of the relevant medical literature, and a talk he gave to the oncology group at his medical center on the topic of bisphosphonate induced ONJ.

Analysis by the Court

Holding the Plaintiff’s evidence to be unpersuasive, the Court said although the contested medical expert witness‘ experience presumably qualified him to testify as an expert with respect to the treatment or diagnosis of ONJ, it did not necessarily qualify him to testify as to the cause of Plaintiff’s ONJ. “The ability to diagnose medical conditions is not remotely the same as the ability to deduce in a scientifically reliable manner, the causes of those medical conditions.” – cited the Court from a previous decision.

Also, to perform a reliable differential diagnosis, the medical expert witness must have made an accurate diagnosis, reliably ruled in all possible causes of the disease, and reliably ruled out the rejected causes, said the Court. In this case the expert failed to scientifically rule out the other potential causes of Plaintiff’s ONJ, such as smoking, chemotherapy, and periodontal disease; instead relying only on his experience as an oral surgeon and the failure of Plaintiff’s condition to respond to treatment to rule out these other potential causes. This was particularly insufficient in the Tenth Circuit, which had held that a differential diagnosis was most useful when the party relying on it had offered additional corroborating evidence.

Therefore since the expert was not qualified to opine as to the specific cause of Plaintiff’s ONJ and did not use a scientifically reliable method in forming his opinion, his causation testimony warranted exclusion.

Final ruling on admissibility of the medical expert witness

Pursuant to the above analysis, the Defendant’s Daubert motion to exclude the medical expert witness’ testimony was granted by the Court and summary judgment was ordered on all of Plaintiff’s claims except sanctions.

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