A federal judge's decision to exclude expert testimony may force hundreds of plaintiffs to drop their claims against Pfizer Inc. that the anti-inflammatory drug Celebrex caused them to suffer heart attacks or strokes.
The judge said that two of the plaintiffs' experts in the multi-district litigation had failed to produce scientifically reliable evidence that the most common dosage of 200 milligrams a day could cause heart attacks or strokes. Lawyers estimated that the ruling could affect between a third and half of pending cases.
"If the court’s gatekeeping function means anything," wrote U.S. District Judge Charles R. Breyer, "it must mean that these unreliable opinions are not admissible to prove general causation at 200 mg/d."
More than 3,000 plaintiffs have filed suit against Pfizer, alleging that Celebrex taken for arthritis caused them or a family member to suffer a heart attack or stroke. The drug's recommended dose is 200 milligrams a day for arthritis and 400 milligrams a day for rheumatoid arthritis.
Evidence of any link between Celebrex at 200 milligrams and cardiovascular disease is scant. No controlled trials have found any association and most observational studies likewise have found no statistically significant association.
Despite this, the plaintiffs' cardiology expert, Dr. Neil Doherty, testified "to a reasonable degree of medical probability" that the 200 milligram dose of Celebrex could increase the risk of heart attacks. Judge Breyer harshly criticized Doherty's basis for reaching his conclusion.
"He reaches his opinion by first identifying his conclusion – causation at 200 mg/d – and then cherry-picking observational studies that support his conclusion and rejecting or ignoring the great weight of the evidence that contradicts his conclusion," Judge Breyer wrote. "Dr. Doherty’s opinion does not reflect scientific knowledge, is not derived by the scientific method, and is not 'good science.'"
Judge Breyer said that Dr. Doherty is not qualified to give weight to certain observational studies over others because he is a clinical cardiologist who devotes 95 percent of his time to patients, not research. "He only became interested in Celebrex and [cardiovascular] risk after he was retained by plaintiffs in this litigation," Judge Breyer wrote.
Plaintiffs' second expert, neurologist Dr. Maryilyn Rymer, also offered her opinion that Celebrex at the 200 milligram dosage can cause strokes. Again, Judge Breyer found that this expert's opinion lacked any scientific foundation. "Dr. Rymer, as does Dr. Doherty, ignores the vast majority of the evidence in favor of the few studies that support her conclusion," Judge Breyer said.
Given his conclusion that neither expert's opinion was scientifically sound, Judge Breyer granted Pfizer's motion to exclude their testimony. "The opinion of Dr. Doherty and Dr. Rymer … is not based on a scientific valid methodology," the judge wrote. "Instead, these experts ignore the great weight of the observational studies that contradict their conclusion and instead rely on the handful that appear to support their litigation-created opinion."
Pfizer was not successful in asking the judge to exclude expert testimony that 400 milligram doses of Celebrex could cause heart attacks or strokes. The judge said that this request was defeated by a long-term clinical trial that was halted after 33 months because it showed a significant risk of heart attack, stroke and heart failure at 400 milligrams.
Judge Breyer described this study as representing the "gold standard" of epidemiologic evidence and said it therefore supports plaintiffs' experts' testimony that Celebrex at 400 milligrams is capable of causing heart attacks or strokes.
In so ruling, he rejected Pfizer's argument that the study's early termination meant it could not be used as the basis for expert opinion. The study was halted, he noted, because the evidence of harm from the drug was so great. "To exclude reliance on such studies under these circumstances would mean the more harmful the drug, the more difficult it is to prove harm."
Judge Breyer also ruled:
- He would not exclude plaintiffs' expert testimony that Celebrex is capable of causing strokes. Even though few Celebrex studies focused on strokes, the expert testified that the mechanism and risk factors for strokes are the same as for heart attacks. Judge Breyer said that, on the record before him, he could not conclude that this testimony "is scientifically invalid and inadmissible."
- He would deny Pfizer's motion to exclude testimony that Celebrex is capable of causing heart attacks or strokes earlier than after 33 months of continuous use.
- He would deny plaintiffs' motion to exclude the meta-analyses of data performed by Pfizer's experts. Plaintiffs' arguments, he said, go to the weight to be given this evidence, not to its scientific basis.
The case is In Re: Bextra And Celebrex Marketing Sales Practices And Product Liability Litigation, MDL No. 1699 (N.D. Calif. Nov. 19, 2007).