Clinical Summary: A Multicenter, Randomized, Controlled, Clinical Trial Evaluating Dehydrated Human Amniotic Membrane in the Treatment of Venous Leg Ulcers

The annual cost of venous leg ulcers – the most common ulceration of lower extremities – amounts to $14.9 billion, yet as many as half of these ulcers fail to achieve healing in 6 months using standard compression therapy. In recent years, the use of amniotic membranes to treat chronic and complex wounds has increased substantially. This randomized controlled trial specifically examines the use of dehydrated human amnion and chorion allograft (dHACA) plus standard of care in the treatment of venous leg ulcers.

The endpoints of this open-label randomized controlled trial included the proportion of ulcers healed in 12 weeks, as well as incidence of adverse events and 40% ulcer closure at 4 weeks. Researchers included 60 patients from 8 wound care centers across the US to compare wound healing in the control group, where standard of care alone was used, with 2 test groups, where dHACA was applied either weekly or biweekly in addition to standard of care treatment. The authors of the study concluded that dHACA applied either weekly or every 2 weeks in addition to standard of care led to significantly improved healing outcomes in venous leg ulcers, constituting a safe and effective care option.

With venous leg ulcers accounting for as many as 60-80% of all leg ulcers, they pose a major burden to the healthcare system, and patients have endured poor healing rates with standard treatments. Amniotic membrane has been increasingly used in many facets of wound healing to improve outcomes in recent years. These structural extracellular matrices consist of collagen types IV, V, and VII, along with growth factors and proteins that support multiple stages of the wound healing process. Improved donor screening, processing, and storage practices have made the use of amniotic products increasingly safe and available to practitioners. In particular, the dHACA used in this study is aseptically processed while preserving its natural structure and biologic activity. Thus, this study sought to assess the effectiveness and safely of this dHACA product (AmnioBand Membrane; MTF Biologics) used in concert with standard of care when compared to standard of care treatment alone.

The study was institutional review board-approved and registered and was designed as a multicenter prospective, open-label randomized controlled trial. Researchers employed a 2-side log-rank test with a 60-subject sample size spread across 8 US wound care centers. Each of 3 groups (1 control and 2 test groups) included 20 subjects, with the control group receiving only standard of care treatment, while each of the control groups received application either weekly or biweekly of the dHACA product in addition to standard of care. The study focused on a primary hypothesis that healing rates at 12 weeks would be equal across all groups.

The dHACA product used in this study (AmnioBand Membrane; MTF Biologics) is an aseptically processed amnion and chorion donated human tissue product regulated under the FDA regulations for homologous use of human tissue. Its intended clinical use is as a wound covering for treatment of venous leg ulcers, burbs, diabetic wounds, and traumatic wounds. The allograft is tested for sterility during the tissue processing and packaging processes, and placenta with amnio and chorion has been donated by mothers who have had healthy, full-term births and passed rigorous screening both before and after donation. The amnion and chorion tissues are then minimally processed, allowing the extracellular matrix to maintain its structural properties, and chemical disinfection is completed through the use of peracetic acid plus ethanol solution without terminal sterilization. Finally, the dHACA is dehydrated and sealed into its packaging. The final product has a shelf life of 3 years and is available both as a single-use, dry disk or a sheet in multiple sizes to cover a variety of wounds sizes.

Screening for study participants included a physical examination, along with collection of patient demographics, and medical and ulcer history. Vitals were recorded and ulcers were assessed using the Silhouette three-dimensional laser camera system by Aranz. An arterial doppler was used or ankle-brachial index measurements taken, and the ulcer was debrided as needed, then treated with compression therapy. Each enrolled patient underwent 14 days of standard compression therapy. After evaluation for all inclusion and exclusion criteria, remaining subjects were blindly randomized into either the control group, the one-weekly dHACA plus standard of care group, or the biweekly dHACA plus standard of care group.

Patients were seen on a weekly basis, regardless of treatment allocation, to assess compression bandage integrity, update any medical history, record adverse or serious adverse events, and asses infection and closure of the ulcer. Every subject received the standard of care treatment at each visit, which included ulcer cleaning and debridement as appropriate, application of a multilayer bandage, and instructions to the patient on limb elevation and care of bandaging. In addition, those in the two test groups received an application of a wound-specific size dHACA over the test ulcer, either at every visit for the weekly group, or every other visit for the biweekly group. Placement of the dHACA was followed by application of a nonadherent dressing, followed by a multilayered compression bandage.

During visits, investigators also took digital photos of the ulcer site, and patients whose ulcers were observed to be healed returned 2 weeks later for a confirmation visit to have vitals taken, photograph the wound, and confirm closure. Furthermore, each closed wound underwent randomized, blinded validation by a team of 3 plastic surgeons to confirm closure. For wounds to be considered closed, 2 out of 3 plastic surgeons must deem the wound closed.

Treatment sites were monitored throughout the study for appropriate data collection and clinical practices, and compiled data was analyzed by an independent statistician (Strategic Solutions, Inc., Bozeman, MT) using SPSS Version 26 (IBM Corp., Armonk, NY). Statistical testing was 2-sided and performed with a significance level of 0.05.

From November 2015 to January 2019, 101 patients were screened for eligibility in the study. Of these, 41 were deemed ineligible, while the remaining 60 were enrolled, with 20 subjects randomized into each group. Baseline variables showed no significant differences between groups, though the biweekly dHACA group showed a numerically larger difference in initial wound area compared with other groups, and the standard of care group presented with a somewhat higher duration of care than other groups. All 60 subjects enrolled in the study received their allocated intervention, and none exited the trial or were lost to follow-up.

The results of the study showed a significantly greater number of healed venous leg ulcers at 12 weeks among the weekly and biweekly dHACA groups compared with the standard of care group. In total, 30% of the standard of care group achieved wound closure at 12 weeks, while 75% of both the weekly and biweekly dHACA groups achieved closure in this time frame. Additionally, 65% of venous leg ulcers saw a percentage area reduction greater than or equal to 40% at 4 weeks in the standard of care group, while 80% of ulcers in the weekly dHACA group and 70% of ulcers in the biweekly dHACA group achieved 40% or greater area reduction at 4 weeks.

During the study, 38 adverse events were recorded, including 9 serious adverse events. The most common events were infection, followed by development of a new ulcer, but no adverse events were related to the study allograft or procedure, and all were resolved with appropriate treatment. There were no amputations or deaths in any of the groups.

According to the study authors, there are few published peer-reviewed, multicenter, prospective, randomized, controlled trials on the use of skin substitute products in the treatment of venous leg ulcers, though the published studies that do exist demonstrate greater healing outcomes with the use of these products compared with standard compression therapy.

The dHACA used in this study is unique, as it has not undergone the terminal sterilization process used on most other commercially available dehydrated amniotic allografts. Such processes are reported to disrupt the collagen fibers and basement membrane, which are essential to the wound healing properties of amniotic tissue. The study itself also displayed robust statistical analysis and low attrition rate. Despite a rather large number of adverse events, as is typical to any venous leg trial, all adverse events were followed to resolution, and none resulted in amputation, death, or withdrawal from the study. The authors posit that the main limitation of the study was the inability to blind patients and investigators due to the nature of the treatment protocols used in each group.

Among the most significant findings was the demonstration of no significant differences in outcomes between the weekly and biweekly dHACA application groups. This suggests that fewer graft applications may be used without affecting the portion of patients who will experience progression to wound healing. The researchers concluded that this study demonstrates the efficacy and safety of the dHACA, regardless of treatment frequency, in achieving greater healing of venous leg ulcers compared with standard of care treatment alone, suggesting that dHACA treatment “should be considered as an adjunct to standard of care of nonhealing venous leg ulcers.”

To learn more, explore the CME course, "A Stepwise Approach to Managing the Spectrum of VLUs: Examining the use of Aseptically Processed Human Allograft Tissue," from the Wound Care Learning Network.

REFERENCE

Serena, TE, MD; Orgill, DP, MD, Ph.D.; Armstrong, DG, DPM, MD, PhD; et al. A multicenter, randomized, controlled, clinical trial evaluating dehydrated human amniotic membrane in the treatment of venous leg ulcers. Plast Reconstr Surg. 2022;150(5):1128-1136. doi: 10.1097/PRS.0000000000009650