FDA’s Still Fledgling MDDT Program

Pre-qualified device evaluation tools have not yet been popular.

Image source: Jane Kelly/Shutterstock

FDA released its final guidance on Medical Device Development Tools (MDDT) in August 2017, following the draft of November 2013. MDDT’s are pre-qualified methods, materials, or measurements that can be used to assess, at least in part, the effectiveness, safety, or performance of a medical device for regulatory submission purposes. The idea behind MDDTs is that the evaluation of a device for market entry (i.e., 510(k) or PMA) would be streamlined if the things that were necessary to perform the evaluation were known in advance to have been proven appropriate. Once a tool was qualified by FDA, it would be accepted without further proof that it was appropriate, thereby reducing the regulatory burden. The burden reduction would be especially true if a tool was going to be used multiple times. As noted in an FDA webinar, CDRH reviewers should accept a qualified MDDT for the already identified context of use without the need to reconfirm the appropriateness of the tool. As shown on the MDDT web page, two MDDTs have been qualified to date, both of which are patient questionnaires in the cardiovascular arena.

FDA identified three types of MDDTs that could be qualified:

  • Clinical Outcome Assessments. Survey instruments that measure how a patient feels or functions (e.g., the questionnaires noted above).
  • Biomarker Tests. Tests or instruments used to detect or measure a biomarker.
  • Non-Clinical Assessment Models. An in vitro, ex vivo, or in vivo (animal) model or method that measures or predicts device function or performance.

The latter category in some ways overlaps the voluntary standards area, but the guidance notes that MDDT is not meant to replace the standard development and recognition process nor FDA’s issuance of device-specific guidance documents. It can be noted here that many performance standards disclaim, sometimes subtlety, that the results generated using the standard are comparable to clinical performance. For example, ASTM F2942, which addresses testing of vascular stents, is an FDA Recognized Consensus Standard. The scope of F2942 includes the statement: “This guide does not provide the in vivo physiologic deformation conditions for a vascular stent.” It is further noted that additional considerations that could influence the results include the test boundary conditions, and vessel calcification, vessel taper, eccentric lesions, loading excursions, and vessel remodeling. This reflects the challenges of properly simulating not only “average” in vivo conditions but also the breadth of in vivo conditions.

Besides the relationships to standards, MDDTs can also have a relationship with the recently announced Expanded Abbreviated 510(k) per its draft guidance, which proposes that testing against specific predetermined criteria, using predetermined test methods, could replace direct comparison of a new device to its predicates.

Qualification of an MDDT is not a simple matter. It begins with a proposal phase that requires a description and justification for the tool, its context of use, its readiness, and its potential role in device evaluation. Two optional steps are the incubator phase and the pre-qualification phase. The goal of the incubator phase is for FDA to work with submitters to foster the development of tools that have the potential to significantly improve public health. The pre-qualification phase is to allow FDA to provide feedback on what evidence would be needed to support qualification. Finally, the qualification phase involves the submission of material that can support a determination that, for a specific context of use, the tool is appropriate based on the evidence and justifications provided.

While only two MDDTs have been qualified, there may be more in the pipeline, but the pipeline is opaque. It may also be the case that reaching the level of assurance that FDA envisions may be technically challenging. This might make the MDDT process itself too burdensome, rather than providing an avenue for burden reduction.

William A. Hyman

William A. Hyman is a professor emeritus in the department of biomedical engineering at Texas A&M University and adjunct professor of biomedical engineering at the Cooper Union. Reach him at [email protected].

500 characters remaining
While the FDA doesn't discuss MDDTs in progress, the sponsor is free to do so. One such example is an effort to validate an in vitro human tissue MDDT for animal free testing of personal lubricants. This is one example of a broader effort to reduce animal testing when other testing can achieve the same objective. See <https://www.piscltd.org.uk/personal-lubricant/> and <http://iivs.org/2017/08/21/collaborative-effort-aims-to-replace-rabbit-test-for-personal-lubricant-products/>