Wound Assessments to Measure Endpoints: An Update From the Wound Care Collaborative Community (WCCC)

Ongoing assessment of chronic wounds is fundamental for appropriate wound management, treatment, and outcomes.^1-5 Accurate and clinically reliable assessments are important in assessing progress towards healing, monitoring risk factors, evaluating the benefit of a therapy, supporting qualification, or clinical justification for advanced therapy and reimbursement.

In a retrospective analysis of 2768 wounds, the authors showed that the length by width method overestimates the area of the wound by over 44%.⁶ Other studies support this overestimation of wound size using L × W measurements.^5,7,8 Large wounds and irregularly shaped wounds exacerbate the inaccuracy.⁹ A comprehensive assessment should include precise dimensions of the wound surface area and examination of the wound bed appearance, tissue characteristics, and amount and color of exudate/drainage.⁹

Digital imaging-based measurement of the wound can be accomplished via various devices, technologies, and even imaging applications within a smartphone or tablet that can reduce the variability of human error when using ruler-type or tracing techniques for wound measurement assessment and increase accuracy over L × W assessments. Digital imaging allows us to record over time for comparison, analyze percentage change in area, and have a documented visual view of the wound and its tissue characteristics. Digital imaging using tools with validated high accuracy and low variability should be the standard method for wound measurements and assessments.

Advanced digital planimetry and 3D wound imaging modalities present the most reliable method to accurately assess and document wounds.^10-12 Beyond practical advantages—such as non-contact measurement, improved documentation, audit of trials, and reduction in clinic workflow/patient cycle time—3D assessments offer a robust method to assess complex wounds and monitor changes with ease and flexibility.

Beyond the basics of size, depth, and tissue quality of a wound assessment, the presence of bacterial loads that inhibit healing¹³ and the vascular status of the wound area can now be considered with imaging technology during evaluation of the wound. There are several devices on the market today with strong clinical evidence of effectiveness and validity^14-16 that can be a vital addition to wound assessment when knowledge of these parameters is needed.

Collectively, members of the WCCC Tools Work Group are gathering information on currently available devices that have the capability to measure PAR and/or PVR as a primary function of the device/application or as a secondary function along with other wound parameter measurements, such as presence of bacterial load, vascular status, tissue oxygenation, etc. Based on this collective work, we will be preparing recommendations to the FDA for devices that meet the criteria and have sufficient clinical validity of their device/application for use in clinical trials and clinical management for the measurement of PAR or PVR as a primary endpoint.

As a wound care community, it is our responsibility to determine the minimum standards for imaging devices that are used by clinicians, patients, caregivers, and health systems—both in clinical practice and clinical trials—that yield accurate, consistent, and reliable images for decision-making. For example, several lines of evidence have demonstrated that typical smart cameras may not be the appropriate vehicle to take an image for wound assessment. Our phones are not medical devices. Most cell phones have built-in software and/or hardware filters in their camera function to maximize the aesthetics of the day-to-day pictures we take and send to family and friends. These filters and the software processing modify the colors of the image, which can distort the color of wound tissue or diminish the edges of the wound, resulting in inaccurate sizing. We as phone users are largely unaware of these modifications, which may change with every software update our phone undergoes.

Understanding the extent of this limitation is within the scope of the WCCC, and its importance will only further increase as telemedicine use in wound care continues to expand. Several projects are evaluating the ability and reliability of these cameras to detect specific colors, such as the red to purple of erythema or red of granulation tissue that clinicians are remotely looking for in images acquired during telemedicine visits.

As the WCCC Tools Work Group collects and analyzes data on the features built into manufacturers’ wound imaging devices that address accuracy, repeatability, reduction of variance, etc., we will share with the wound care community our findings and will publish our evaluation and recommended criteria for imaging devices going forward. 

You can be part of this effort by visiting www.woundcarecc.org and becoming a WCCC member.

Presently, digital imaging tools with proven high accuracy and low variability are widely available, should be the standard method for all wound measurements, and are explicitly recommended. The WCCC will be preparing recommendations to the FDA for the specific devices that have sufficient clinical validity of their device/application for use in clinical trials and clinical management for the measurement of PAR or PVR as a primary endpoint. 

Advanced imaging capabilities, such as bacterial load detection imaging and perfusion imaging, have strong potential for more accurate and thorough physiological assessment and will be a future focus of the WCCC Tools Group.