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Reducing Noise with Trial Design to Improve Wound Healing Trials

The U.S. FDA maintains a very narrow definition of complete wound closure as skin reepithelialization without drainage or dressing requirements confirmed at two consecutive study visits two weeks apart. With this definition, it is often difficult to demonstrate the efficacy of a new product, and this challenge is amplified if the trial is not carefully designed from the start due to noise related to selection of appropriate patient population, standard of care and wound characteristics.

Failing to consider these factors can prevent sponsors from achieving statistically significant results that demonstrate efficacy and earn approval. Careful trial design, however, helps avoid these issues. By acknowledging these challenges early in the design process, sponsors benefit from greater study accuracy, improved results and a higher chance of success when seeking FDA approval.

Highly Specific Recruitment

Finding the ideal patient population for wound healing is a careful balance between identifying patients whose wounds are unlikely to heal on their own but may still heal with intervention and avoiding those with wounds too severe to heal during the proposed duration of the trial. The size of the wound, depth of the wound and overall severity affect wound closure success and timelines, so it is best to not only select patients with hard-to-heal wounds, but to also conduct a run-in period to assess wound healing before the trial begins.

This process involves identifying patients who agree to participate in a trial and then monitoring wound healing progress with the standard of care after a specified duration, usually two to four weeks. If we look at diabetic foot ulcer (DFU) patients, for example, the ideal patient population would be those with hard-to-heal wounds. In this case, patients who have less than 20% or 30% reduction in wound size over a four-week period with the standard of care would be ideal. This process does not impact study time but ensures a more targeted population and reduces noise related specifically to wound variation.

Consistent Standards of Care

Establishing and ensuring a consistent standard of care for trial patients, across all medical centers and regions, is one of the most difficult aspects of trial design. The definition of “standard of care” may vary depending on the clinic or country (for global studies) along with how closely the guidelines are followed. Part of this also rests on patient compliance with aspects such as offloading, or taking pressure off the wound. In some cases, there may be devices that help encourage compliance, but patient access must also be considered. To help minimize noise in this area, sponsors and researchers must clearly specify what is expected for the standard of care for all patients, meaning this must be established during the trial design phase.

In addition to these measures, an adaptive trial design allows you to take noise into account during the trial to adjust the sample size based on pre-established criteria. Adaptive clinical trials are accepted by the FDA but require the attention of an experienced research team or partner to properly maintain trial integrity. Amarex has experience with designing and leading successful wound healing studies and remains an advocate of adaptive clinical trials for many therapies and products.

Listen to Dr. Kazem Kazempour and Dr. Kush Dhody discuss the challenges of a successful wound healing trial on the “Speaking of Wounds” podcast hosted by Jaclyn Gaydos. Or contact Amarex to learn more about how we can help you achieve success with your clinical trials.


Demonstrating the efficacy of a new wound healing product remains challenging. Learn how reducing the potential noise in a clinical trial helps enable success.

You know the FDA definition of wound healing. And your product is ready for trials. But have you taken the necessary steps to reduce noise?

Reducing noise for your wound healing product begins in the trial design phase, but it doesn’t stop there. Jaclyn Gaydos, host of the “Speaking of Wounds” podcast, speaks with Amarex’s Dr. Kazem Kazempour and Dr. Kush Dhody about key challenges and potential solutions.

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