A New Jersey federal court granted summary judgment to Baxter Healthcare Corporation (Baxter) last month based on a familiar legal concept rarely applied in the Garden State – warning causation. In Baker et al. v. APP Pharmaceuticals LLP et al., No. 3:09-05725 (D.N.J., Aug. 21, 2012), the Court held that even if the warning label at issue was inadequate, which it was not, it could not have proximately caused the plaintiff’s injury because the prescribing physician was already aware of the product’s risks, chose not to read its label, and stood by his decision to administer the therapy. The Court’s decision in Baker provides additional support for pharmaceutical manufacturers seeking to demonstrate a lack of proximate causation.

In Baker, plaintiff Evangeline Baker alleged that the administration of heparin, an anticoagulant manufactured by Baxter that prevents blood clots, caused her to develop heparin-induced thrombocytopenia (HIT) as well as heparin-induced thrombocytopenia and thrombosis (HITT), ultimately resulting in the amputation of her leg. Despite the fact that heparin’s FDA-approved labeling contained information about HIT and HITT in the “Warnings” section, the plaintiff alleged that Baxter failed to adequately warn of the dangers of the product.

At the outset, the Court addressed why the “super-presumption” afforded by the New Jersey Products Liability Act (PLA) to FDA-approved prescription drug labels was not rebutted in this case. Under the PLA, a plaintiff may rebut the presumption of adequacy of a drug label with evidence of “intentional misconduct by the manufacturer.” Bailey v. Wyeth, Inc., 37 A.3d 549, 569 (N.J. Super. Ct. Law Div. 2008). Here, the plaintiff was not able to demonstrate that Baxter deliberately concealed relevant information from the FDA – known as “the Perez exception” – nor did she offer any evidence that Baxter manipulated the post-market regulatory process for profit – known as “the McDarby exception.” See Perez v. Wyeth Labs., Inc., 734 A.2d 1245, 1259 (N.J. 1999); see also McDarby v. Merck & Co., Inc., 949 A.2d 223, 256 (N.J. Super. Ct. App. Div. 2008). Consequently, the Court found that Baxter was entitled to summary judgment because its warning was adequate under the PLA.

While the Court’s analysis could have ended there, it went on to explain that even if Baxter’s warning had been inadequate, summary judgment would still be appropriate because the warning was not the proximate cause of the plaintiff’s injury. In doing so, the Court laid out a roadmap for a successful warning causation defense.

In New Jersey, pharmaceutical defendants often times do not assert the warning causation defense due to New Jersey’s “heeding presumption.” That rule provides that, if an adequate warning had been given, the prescribing physician presumptively would have read and heeded it, and, thus, would not have prescribed the drug to the plaintiff. To meet his or her burden, a plaintiff must “show that adequate warnings would have altered [his or her] doctors’ decision to prescribe the drug.” In this case, however, the Court found that the presumption was adequately rebutted by the testimony of the prescriber.

First, the prescriber stated that he regularly used heparin in his cardiac surgery practice, was familiar with its risks and benefits, including the risk of HIT, and “stood by his decision to administer heparin to Mrs. Baker.” Second, he admitted that he does not read the label of drugs he frequently prescribes, including heparin. Finally, the prescriber “never testified that he would have consulted a black box warning or ‘Dear Doctor’ letter, or that he ever reviewed the Physicians’ Desk Reference when prescribing heparin. Therefore, a different warning would not have made a difference in Mrs. Baker’s treatment or outcome because [the prescriber] would not have reviewed it.” Thus, as the learned intermediary, the physician’s conduct broke the chain of causation between Baxter and the plaintiff.

In a state overflowing with pharmaceutical litigation, warning causation has been effectively applied in surprisingly few cases. The in-depth analysis of Baker provides support for a causation defense that pharmaceutical defendants will want to evaluate as part of their defense strategy in failure to warn cases.