INTRODUCTION

In patients with diabetes mellitus, diabetic foot ulcers (DFUs) are the fastest-growing chronic complication with an annual incidence of 2.4% to 2.6% and prevalence of 4% to 10% worldwide.1 Even after a DFU has healed, recurrence is common: Approximately 40% of patients have a recurrence within the first year after ulcer healing, almost 60% within 3 years, and 65% within 5 years.2 Management of patients with DFUs follows a holistic approach, with standard-of-care treatments including regular debridement, offloading, metabolic control, treatment of comorbidities, local ulcer care, regular foot care, and vascular assessment. Despite improved outcomes following standard treatment, more than half of DFUs become infected, with approximately 20% of moderate or severe diabetic foot infections leading to some level of amputation.2 Hicks et al3 reported 30-day readmission rates of more than 20% for patients with DFUs with an average inpatient stay of 9 days, resulting in more than double the cost of care per patient from US $28,977 to US $79,315.3

In addition to standard practice in DFU care, a range of adjuvant therapies are used.4 However, evidence to support many adjuvant therapies in DFU care is either lacking or is of poor quality.5 In this study, the authors sought to demonstrate the effectiveness of one such adjuvant treatment option—the autologous multilayered leukocyte, platelet, and fibrin (MLPF) patch (3C Patch System, Reapplix Inc), which has been shown to promote DFU healing.6

The MLPF patch releases cells, cytokines, and growth factors involved in tissue repair, angiogenesis, and inflammation,7 which are paramount to wound healing. Through a unique process of centrifugation of autologous blood using a wound management system that includes a single-use medical device, a triple-layered leukocyte, platelet, and fibrin patch composed of distinct parallel layers is formed.7 The MLPF patch has been shown to be safe and effective in several clinical trials,8–10 including a large, randomized controlled trial (RCT) with 269 participants.6 Outcomes of this RCT showed a statistically significant effect of the MLPF patch on the incidence of healing, time to healing, and wound area changes in comparison with standard of care in a relevant hard-to-heal patient population, including patients with vascular issues and deep ulcers with probe to bone.6 Based on these data, the International Working Group on the Diabetic Foot recommends use of the MLPF patch as an adjunctive treatment in difficult-to-heal noninfected DFUs, in conjunction with best standard of care.11 Based on thorough data reviews,12–14 CMS recently released a national coverage decision15 to cover the use of platelet-rich plasma systems with an FDA-cleared wound indication, including the MLPF patch, for the treatment of chronic, nonhealing diabetic wounds.

Real-world data (RWD) refers to data collected from sources others than RCTs that can be used to support clinical interpretation of how products act in a diverse patient population, thus providing a line of complementary real-world evidence.16–18 The main objective of this retrospective data analysis was to describe the effectiveness of the MLPF patch when used in the real-world clinical setting of two amputation preventive centers in the US.

METHODS Study Design and Objective

In this retrospective observational study, the authors used chart data from patients’ paper and electronic health records to investigate real-world experiences and clinical outcomes of the use of the MLPF patch as an adjunctive treatment in addition to best standard of care (following guidance from the International Working Group on the Diabetic Foot11 and the CMS national coverage decision13,15). Based on the retrospective nature of this work, the study received waiver authorization from the WCG Institutional Review Board, Puyallup, Washington, US.

The main objective of this study was to describe the healing progression of chronic, hard-to-heal DFUs treated with the MLPF patch in a challenging patient population with comorbidities that represent the majority of patients attending the facility centers.

Patient Population

Patients were included in this retrospective analysis if they were treated with at least one application of the MLPF patch at the discretion of the treating physician at the PULSE Amputation Prevention Center or Casa Colina Hyperbaric Medicine & Wound Care Center between September 2021 and October 2022. The sample included adult patients (18 years and older) who had a diagnosis of diabetes and presented with a chronic DFU that had failed to progress along a timely repair sequence during treatment despite sharp debridement, local wound care, and adequate offloading.

MLPF Patch Procedure

The MLPF patch was produced from 18 mL of the patient’s blood as described by the manufacturer (Reapplix Inc). The process included drawing blood into the 3C Patch vacuum device and inserting the device into the proprietary centrifuge. The automated blood processing took approximately 20 minutes on average and included the three phases of centrifugation, coagulation, and compaction.19 After this process was complete, the provider removed the patch from the vacuum device and applied it to the wound. Each MLPF patch was fully autologous, readily transferable to the patient, and displayed a three-layered structure of leukocytes, platelets, and fibrin that resulted in cell and growth factor being released into the wound bed. The MLPF patches were generally applied to DFUs on a weekly basis, depending on patient availability and clinical need as assessed by the treating physician. All MLPF patch production and application procedures were conducted by a healthcare professional.

Data Extraction

Researchers extracted data related to patients’ demographics (sex, age), clinical profile and comorbidities (presence of chronic kidney disease, neuropathy, glycated hemoglobin [HbA1c] level, peripheral vascular disease [PVD], revascularization data, prior amputation, other comorbidities), and DFU (Wagner grade, foot infection, wound size, wound age, wound location, and secondary wound dressings used) from paper and electronic health records by the clinical research coordinator and checked for accuracy by coauthors. Wounds were classified by the treating physician according to the WIfI classification system based on Wound (W), Ischemia (I), and foot Infection (fI).20 Likewise, complete wound closure data were extracted at the follow-up. All data were deidentified and entered into an Excel spreadsheet (Microsoft Corp) before data analysis.

Data Analysis

Descriptive statistics were performed for baseline and outcome data, with nominal values and percentages for categorical variables and the mean and range (min-max) for continuous variables. Healing rate, time until complete epithelialization, and wound area change during treatment were analyzed. Ulcer healing over time was evaluated by Kaplan-Meier analysis. Further, a subgroup analysis of data was conducted based on WIfI-based amputation risk stratification. A Student t test was used to compare differences between groups (healers vs nonhealers). P < .05 was considered statistically significant. Analysis was performed using Excel for Windows and GraphPad Prism version 9.4.1 for Windows (GraphPad Software).

RESULTS

A total of 36 patients with 38 DFUs that were treated at least once with an MLPF patch between September 2021 and October 2022 were included in this retrospective analysis. Patient demographics and baseline characteristics are summarized in Table 1. Patients selected for MLPF patch treatment by the treating physician all had chronic nonhealing diabetic wounds that had failed to respond to conventional wound care, despite weekly sharp debridement, local wound care, and adequate offloading.

Table 1. - PATIENT DEMOGRAPHICS AND CHARACTERISTICS AT BASELINE (N = 36) Variable Mean (Range) or n (%) Age, y 62.5 (36–89) Sex, male 29 (81) Diabetes type II 36 (100) Body mass index, kg/m2 27.5 (19.4–49.5) HbA1c, n = 18 7.9 (5.6–10.6) CKD 9 (25) Dialysis 6 (17) Neuropathy 31 (86) PVD 28 (78) Prior revascularization 20 (56) Prior amputation 15 (42)

Abbreviations: CKD, chronic kidney disease; HbA1c, glycated hemoglobin; PVD, peripheral vascular disease.

The key outcomes evaluated were the percentage of DFUs obtaining complete wound closure within 12 and 20 weeks of the first application and during the extended follow-up. Average time to complete closure was compared among groups based on risk of amputation as predicted by WIfI classification. The authors also analyzed wound area changes from first to last MLPF patch application visits.

Patient Characteristics

All patients included in this retrospective RWD analysis had a diagnosis of type 2 diabetes, and 29 patients (81%) were male. Average age was 61.4 years (range, 36–89 years), and average body mass index was 29.2 kg/m2 (range, 19.4–49.5 kg/m2). Average HbA1c was 7.9 (range, 5.6–10.6; limited data set available, n = 18). Peripheral vascular disease was diagnosed in 27 patients (78%). Twenty patients (56%) had previously undergone a peripheral vascular procedure, and 30 patients (83%) were on anticoagulation medication. Further, 6 patients (17%) were on hemodialysis, and 15 patients (42%) had undergone a prior amputation. No history of antibiotic treatment was noted for 19 patients (53%). Systemic I.V. antibiotic treatment had previously been provided to nine patients (25%), and oral treatment to eight patients (22%).

Wound Characteristics

Wound characteristics are presented in Table 2. The average wound size was 4.9 cm2 (range, 0.12–39 cm2), and average wound duration was 9.5 months (range, 1–60 months). Wounds were located at the plantar foot in 15 cases (39%), toe in 5 cases (13%), transmetatarsal amputation site in 5 cases (13%), lateral foot in 5 cases (13%), lower leg in 6 cases (16%), and heel in 2 cases (5%). According to Wagner grade, 3 wounds (8%) were classified as grade 1, 34 (89%) as grade 2, and 1 (3%) as grade 3. Using the WIfI classification, from 38 treated wounds, 12 patients (32%) were predicted to have a low risk, 15 (39%) to have a moderate risk, and 11 (29%) to have a high risk of amputation.

Table 2. - WOUND CHARACTERISTICS AT START OF MLPF PATCH TREATMENT (N = 38) Characteristics Mean (Range) or n (%) Wound size, cm2 4.9 (0.12–39) Wound age, mo 9.5 (1–60) Wagner wound grade  1 3 (8)  2 33 (89)  3 1 (3) WIfI classification-based risk for amputation  Low 12 (32)  Moderate 15 (39)  High 11 (29) Wound locations  Plantar foot 15 (39)  Toe 5 (13)  Transmetatarsal amputation 5 (13)  Lateral foot 5 (13)  Lower leg 6 (16)  Heel 2 (5)

Abbreviations: MLPF, multilayered leukocyte, platelet, and fibrin; WIfI, Wound, Ischemia, and foot Infection.

Several devices were used for DFU offloading. Total contact casting was used in 11 cases (29%), postoperative shoes in 10 cases (26%), wheelchair in 10 cases (26%), Cam/Unna Boot in 2 cases (5%), podiatric felt in 3 cases (8%), and no offloading was specified in 2 cases (5%).

The MLPF patches were applied weekly, with between 1 and 20 applications (mean, 8.4 applications) per patient. The patch was used with different types of secondary dressings according to the individual needs. No adverse effects as a result of MLPF patch use were observed.

Healing Outcomes

Results for wound outcomes are presented in Figure 1 and Table 3. For area change, data from 35 of 38 wounds were analyzed: two outliers were detected (merged with adjacent wounds), and for one wound, only one data point was available. The results indicate that the MLPF patch used in conjunction with sharp debridement, local wound care, and offloading resulted in complete closure of most wounds during the treatment and follow-up phase (Figure 1).

Figure 1.:

PERCENT OF WOUNDS CLOSED (N = 38)

Table 3. - WOUND OUTCOMES (N = 38) Outcome Mean (Range) or n (%) Healed within 12 wk 9 (24)  Average time to heal, d 51 (27–69) Healed within 20 wk 23 (61)  Average time to heal, d 91 (27–140) Healed overall 30 (79)  Average time to heal, d 109 (27–183) Wound size, cm2 (P = .66)  Healed 5.2  Not healed 3.8 Wound age, mo (P = .38) Healed 10.2 Not healed 6.8

The treatment phase was defined as the length of time between the first and last MLPF patch application and varied by patient. After 12 weeks, complete healing and epithelialization were noted in 9 wounds (24%), with an average time to healing of 51 days (range, 27–69 days). After 20 weeks, 23 wounds (61%) were closed, with an average time to heal of 91 days (range, 27–140 days). Within the extended follow-up (ranging from 20 to 50 weeks), 30 wounds (79%) healed with an average time to heal of 109 days (range, 27–183 days).

The authors compared wounds that healed versus those that did not heal (Table 3). Average wound age was 10.2 months for wounds that healed and 6.8 months for wounds that did not heal (P = .38). The average initial wound size was 5.2 cm2 for healed wounds and 3.8 cm2 for wounds that did not heal (P = .66).

Results from subgroup analysis based on risk for amputation (WIfI) are presented in Figure 2. The group of patients with a predicted low risk of amputation experienced a high healing rate (92%). The moderate- and high-risk groups both experienced the same healing rate (73%), despite the high-risk patients having a greater number of prior amputations and infections.

Figure 2.:

COMPLETE HEALING, PRIOR AMPUTATION, AND PREVIOUS INFECTION IN DFUs WITH LOW, MODERATE, AND HIGH RISK OF AMPUTATION BASED ON WIfI CLASSIFICATION (N = 36)Abbreviations: DFU, diabetic foot ulcer; WIfI, Wound, Ischemia, and foot Infection.

Figure 3 represents the percentage of wounds closed as a function of time (Kaplan-Meier survival curve) stratified by WIfI subgroups. In the groups of patients classified as having low and moderate risk of amputation, the first patient to heal did so after 27 and 48 days, respectively. In DFUs classified as high-risk, the first patient healed after 109 days.

Figure 3.:

PERCENTAGE OF WOUNDS CLOSED BASED ON WIfI CLASSIFICATION SUBGROUPS (N = 38)Abbreviation: WIfI, Wound, Ischemia, and foot Infection.

Figure 4 provides individual patient data on wound size (wound area at first and last MLPF patch applications, or complete closure if obtained at the following intended treatment visit). Two wounds were excluded from area analysis because they merged with neighboring wounds during treatment. Overall, 30 wounds (79%) decreased in size during the treatment phase, and 24 wounds (63%) decreased more than 50%. Of the 30 wounds that healed, 8 closed completely during the active MLPF patch treatment phase, 15 healed after active treatment but within 20 weeks of the first application, and 7 healed during follow-up.

Figure 4.:

WOUND AREA AT FIRST AND LAST DAY OF MLPF PATCH APPLICATIONAbbreviation: MLPF, multilayered leukocyte, platelet, and fibrin.

Five patients (13.9%) had a total of eight hospitals stays during treatment or follow-up with an average length of stay of 2.5 days. There were no amputations in the treated patients during the treatment and follow-up periods. No device-related adverse events were found during the study or follow-up; however, one patient reported discomfort with venipuncture and requested the treatment to be discontinued.

DISCUSSION

The results of this retrospective RWD analysis indicate significant healing benefits associated with weekly MLPF patch applications for hard-to-heal DFUs, confirming existing evidence.6 In the present study, 61% of DFUs healed within 20 weeks, which is a higher number than was reported in the RCT in which 34% of DFUs healed in the per-protocol population.6 This difference may be explained by the standardized workflows the authors have established in the study centers and in carefully selecting adherent patients who can benefit from MLPF patch treatment. This RWD contrasts with the more strictly defined inclusion and exclusion criteria used in the RCT.

Peripheral vascular disease and consequent low ankle-brachial index (ABI) values are well-known risk factors for concomitant cardiovascular diseases and increased mortality in patients with diabetes who present with DFUs.21 In this study, 78% of patients were diagnosed with PVD. However, the authors did not stratify collected data by ABI values because patients with DFUs often have vascular conditions that are complex. In addition, there are some important limitations with ABI measurements, especially in patients with neuropathy, with a risk of falsely elevated ABIs underestimating the severity of PVD.22

To compare study group outcomes, the authors stratified DFUs according to the WIfI classification system. This system scored highest for prospective use in clinical management for the expert assessment and reassessment of peripheral arterial perfusion.20,22 The majority of patients had low to moderate risk of amputation based on WIfI classifications and responded well to MLPF patch treatment. Of 38 wounds, 30 healed in total, either during the treatment phase, after active MLPF patch treatment but within 20 weeks of the first application, or during the follow-up period.

The number of MLPF patch applications varied by patient. Variations were partly due to patient availability and interest in continued treatment and partly due to assessment of wound progress. In some cases, a few MLPF patch applications helped to improve healing sufficiently to eventually achieve complete wound closure. These observations align well with the concept of overcoming wound chronicity by the addition of growth factors and immune cells that are known factors involved in an acute wound healing response.

Although RWD analysis is a recognized and validated methodology to support real-world evidence, working with secondary data increases the measurement complexity in comparison with primary data collected in RCTs involving a selected study population.16–18,23 The strength of this retrospective study is the analysis of a challenging patient population with comorbidities and hard-to-heal DFUs, which represents most patients attending the facility centers. The authors obtained helpful information to complement existing evidence for MLPF patch treatment with the centers’ own experiences.

Observations made in clinical trials6,8–10 that the procedure to generate MLPF patches from the patient’s blood sample is safe, simple, quick, and easy to implement in clinical practice were confirmed in this study. The patch was utilized with different types of secondary dressings according to the individual needs, and no adverse effects were observed as a result of MLPF patch use.

Thirty-day readmission rate has increasingly become a key quality metric. Identifying a treatment that can manage patients with hard-to-heal DFUs is critical to addressing the associated cost burden.3 In the present study, 5 of 36 patients (13.9%) were readmitted to the hospital in the first 30 days with a total of 8 admissions (1.6 per patient). In contrast, Hicks et al3 reported 30-day readmission rates of more than 20% for patients with DFUs, with average inpatient stays of 9 days. In that study, 35 of 150 patients were readmitted within 30 days (23.3%), with a total of 43 readmissions and an average duration of 9.0 days. Thus, 40% fewer patients experienced a readmission within 30 days in the present study compared with the findings of Hicks et al3 (13.9% vs 23.2%), and the average admission duration was 72% shorter (2.5 vs 9.0 days). These significant reductions in 30-day readmission rate and average length of stay suggest that MLPF patch use in patients with hard-to-heal DFUs will have a dramatic economic impact. These study experiences might help clinicians in their efforts to implement use of the MLPF patch in daily clinical practice of treatment of hard-to heal DFUs.

Limitations

A main limitation of this retrospective RWD study is that only two centers in the US participated, and a relatively small number of patients with hard-to-heal DFUs were involved. There are some inherent limitations in RWD because the data describe a limited number of patients in a variable population. Therefore, extrapolation of RWD to other populations and clinical settings should be done cautiously and be supported by controlled clinical data. As such, RWD describe actual clinical use, and clinical efficacy should be assessed in combination with available RCT data.

CONCLUSIONS

The MLPF patch actively modulates the wound environment of hard-to-heal DFUs to release stimulating growth factors and signals from activated thrombocytes and leukocytes within the MLPF patch.24 In a real-world clinical setting of two amputation preventive centers in the US, treatment with the MLPF patch resulted in wound progression and wound healing in the majority of treated wounds in a patient population with type 2 diabetes and hard-to-heal DFUs that had failed conventional wound treatment. Thus, the MLPF patch should be considered a viable adjunctive treatment for DFUs. With the noted reduction in 30-day readmission rates and shorter admission duration, MLPF patch use will have a dramatic economic impact on the care of patients with hard-to-manage DFUs.

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