Statistics Expert References International Data In Hip Implant MDL


Statistics Expert

Court: United States District Court for the Northern District of Texas, Dallas Division
Jurisdiction: Federal
Case Name: Re DePuy Orthopaedics, Inc.
Citation: 2016 U.S. Dist. LEXIS 194777

This case involves multidistrict litigation (MDL) against defendant device manufacturer, DePuy Orthopaedics, Inc. regarding the design, development, manufacture, and distribution of the Pinnacle Acetabular Cup System hip implants (Pinnacle device). The device, which was used to replace diseased hip joints, intended to remedy conditions such as osteoarthritis, rheumatoid arthritis, avascular necrosis, or fractures, and provide patients with pain-free natural motion over a longer period of time than other hip replacement devices.

There were 8,000+ cases in this MDL involving Pinnacle devices lined with metal, ceramic, or polyethylene in their sockets. The plaintiffs acted through a large group of plaintiffs’ lawyers that formed the Plaintiffs’ Steering Committee, which in turn was headed by the Plaintiffs’ Executive Committee, a small group from the Plaintiffs’ Steering Committee appointed by this Court to conduct discovery and other pretrial proceedings and identify common issues in the MDL.

On July 15, 2016, the court entered a scheduling order providing that 6 cases involving California plaintiffs Andrews, Davis, Metzler, Rodriguez, Standerfer, and Weiser be set for a third bellwether trial.

The plaintiffs retained an expert in statistics and biostatistics to offer opinions regarding the relative performance of artificial hip implants with different bearing surfaces. The expert opined that data from the National Joint Registry for England, Wales, and Northern Ireland suggested a Pinnacle metal-on-metal revision rate of 41% at 15 years post initial surgery. He further stated that combined data from an internal DePuy registry and its clinical studies suggested a Pinnacle metal-on-metal revision rate of 64% at 15 years post initial surgery.

DePuy Orthopaedics moved to exclude the opinions of the plaintiffs’ statistical expert witness. The defendant contended that the expert’s opinions were based on statistical extrapolations of existing data into future years versus an analysis of the actual revision rate at 15 years post primary surgery, for which no data was available. The defendant argued that the court’s previous review of this issue misunderstood the defendants to contest the accuracy of the statistics expert’s analysis, rather than the methodology. To the contrary, this court found in the previous bellwether, and affirmed here, that the plaintiff expert’s statistical methodology, the application of a fitted quadratic model to observed hazard rate data, was a common and well-accepted statistical method that can be subjected to testing, verification, and cross-examination.

In was held that the defendant’s position was more appropriately an attack made on the weight of the testimony at trial rather than its admissibility. Thus, the defendant’s motion to partially exclude the opinions and testimony of the plaintiffs’ statistics expert was denied.

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