Toxicologic Pathology Forum*: Opinion on Assessing and Communicating Adversity for Implantable Medical Devices.

Medical devices are a product class encompassing many materials and intended uses. While adversity determination is a key part of nonclinical safety assessments, relatively little has been published about the unique challenges encountered when determining adversity for implantable medical devices. The current paper uses the Society of Toxicologic Pathology (STP)'s "Scientific and Regulatory Policy Committee Recommended ('Best') Practices for Determining, Communicating, and Using Adverse Effect Data from Nonclinical Studies," which were crafted for conventional bio/pharmaceutical products (small and large molecules, cell and gene therapies, etc), as a framework for making adversity decisions for medical devices. Some best principles are directly translatable to medical devices: (1) adversity indicates harm to the animal; (2) effects should be assessed on their merits without speculation regarding future or unmeasured implications; (3) adversity decisions apply only to the test species under the specific conditions of the nonclinical study; and (4) adversity decisions and supporting evidence should be clearly stated in reports. However, unique considerations also apply for evaluating implanted medical devices, including testing of multiple articles in the same animal and the unavoidable tissue trauma during device implantation. This opinion piece offers suggestions for applying previously published STP best practice recommendations for assigning adversity to implantable medical devices.