In Roper v. Secretary of Health and Human Services, the petitioner claimed that the tetanus vaccine caused her to develop chronic gastroparesis. The plaintiff’s expert had published in a medical journal a report of the plaintiff’s medical case and the cases of four other individuals who suffered from gastroparesis. One case developed gastroparesis after tetanus vaccination (the petitioner herself); one experienced gastroparesis after hepatitis B vaccination; one after anthrax vaccination; and two after episodes of Lyme Disease. The expert and his colleagues concluded in the article that the five cases provide strong evidence that gastroparesis can develop in response to an inflammatory condition such as Lyme Disease or a vaccination.
The expert posited this medical theory based on his practice of medicine. The special master found that the medical theory was reasonable, in part because the expert specialized in disorders of the type from which the petitioner suffered, and because in his practice the expert saw more patients with gastroparesis than all but a small handful of physicians. However, the special master’s decision may not have been based solely on the expert’s experience and the five reported cases. In addition, the expert’s article noted that the tetanus vaccine had been found in the past to be a likely cause of the nervous system disorders Guillain-Barre Syndrome and brachial neuritis, and that neurologic disorders had also been reported after hepatitis B and anthrax vaccinations.
The Roper decision therefore shows that case reports authored by the plaintiff’s own expert in a peer-reviewed scientific journal can render support to a medical theory under Althen’s Prong 1. However, publication of case reports alone might be insufficient to satisfy the prong. In Roper, there was additional evidence supporting the theory and the peer-reviewed publication. The special master might have been willing to consider evidence outside the precise disease-scenario alleged in the case – i.e., to consider neurologic injuries associated with hepatitis B and anthrax vaccination, as providing some support for the claim that tetanus vaccination can cause gastroparesis. A question for future cases is how much and what kind of other evidence would be relevant?
In general, therefore, we are left to wonder whether a medical theory based merely on case reports would be enough to prove Prong 1 of the Althen test of causation. And if more evidence is needed, what additional evidence would be necessary or sufficient? Is there some kind of balancing test at work? This is a situation to watch for in other cases.