In re: Onglyza (Saxagliptin) and Kombiglyze (Saxagliptin and Metformin) Products Liability Litigation

(Editor’s Note: The excerpt in Evidence: Practice, Problems, and Rules, Best, 4th Ed., uses the incorrect citation 95 F.4th 339 (2024).) Bristol-Myers Squibb, AstraZeneca, and McKesson (collectively, the companies) (defendants) manufactured diabetes drugs containing saxagliptin. After a study called SAVOR found a 27 percent increase in hospitalization for heart-failure rates in participants taking saxagliptin versus participants taking a placebo, saxagliptin users who suffered from heart failure (the saxagliptin users) (plaintiffs) sued the companies, alleging that their drugs caused heart failure. Regarding causation, the saxagliptin users presented expert testimony from one expert, Dr. Parag Goyal. Goyal relied on SAVOR and did not address four other studies that used human data and did not find any statistically significant connection between saxagliptin and heart failure. Goyal also relied on animal studies in his opinion. To reach his conclusions on causation, Goyal used Bradford Hill, a methodology for analyzing causal links. However, Goyal cherry-picked data in his analysis and also changed his analysis on two of the Bradford Hill factors after issuing his report. At a Daubert hearing, Goyal acknowledged the results of the other human studies and that those studies were reasonably designed. Goyal also acknowledged that he was unqualified to make diagnoses based on animal studies. The district court granted the companies’ motion to exclude Goyal’s testimony and then their motion for summary judgment. The saxagliptin users appealed.