Aqueous oxygen peroxide treatment of VLUs in a primary care-based randomised, double-blind, placebo-controlled trial

Review of the Current Evidence for Topical Treatment for Venous Leg Ulcers

OBJECTIVE

The development of a venous leg ulcer (VLU) represents the most severe clinical manifestation of a chronic venous disease. Despite major progress, there is a limited understanding of VLU pathogenesis and wound healing biology. Treatment of VLUs remains a serious challenge for physicians of different specialties. This communication focuses on describing the rationale and scientific basis for topical wound care in the management of VLUs.

METHODS

A literature review was performed to summarize methods with proven efficacy in VLU management. A systematic literature search was also performed to identify new evidence from the randomized controlled trials published within 2014-2021. The scientific challenges, clinical practice concerns, economic obstacles, and possible directions for further research have been discussed.

RESULTS

Hundreds of topical products have been advertised for the treatment of VLUs. Published data on topical treatment of venous ulcers is insufficient, scattered, weak, and has significant methodological flaws. Forty-three randomized controlled trials on topical treatment of VLUs have been published within 2014-2021. Clinical practice guidelines need to be updated. Major gaps in knowledge have been identified, and suggestions for future research directions have been provided.

CONCLUSIONS

The American Venous Forum Research Committee would like to bring attention to topical wound care for VLUs as a critical gap in knowledge, and encourage scientists, practitioners, and industry to collaborate to fill this gap.

Wound cleansing for treating venous leg ulcers

BACKGROUND

Leg ulcers are open skin wounds that occur below the knee but above the foot. The majority of leg ulcers are venous in origin, occurring as a result of venous insufficiency, where the flow of blood through the veins is impaired; they commonly arise due to blood clots and varicose veins. Compression therapy, using bandages or stockings, is the primary treatment for venous leg ulcers. Wound cleansing can be used to remove surface contaminants, bacteria, dead tissue and excess wound fluid from the wound bed and surrounding skin, however, there is uncertainty regarding the effectiveness of cleansing and the best method or solution to use.

OBJECTIVES

To assess the effects of wound cleansing, wound cleansing solutions and wound cleansing techniques for treating venous leg ulcers.

SEARCH METHODS

In September 2019 we searched the Cochrane Wounds Specialised Register; the Cochrane Central Register of Controlled Trials (CENTRAL); Ovid MEDLINE (including In-Process & Other Non-Indexed Citations); Ovid Embase and EBSCO CINAHL Plus. We also searched clinical trials registries for ongoing and unpublished studies, and scanned reference lists of relevant included studies as well as reviews, meta-analyses and health technology reports to identify additional studies. There were no restrictions with respect to language, date of publication or study setting.

SELECTION CRITERIA

We considered randomised controlled trials (RCTs) comparing wound cleansing with no wound cleansing, or RCTs comparing different wound cleansing solutions, or different wound cleansing techniques.

DATA COLLECTION AND ANALYSIS

We screened studies for their appropriateness for inclusion, assessed their risk of bias using the Cochrane 'Risk of bias' tool, and used GRADE methodology to determine the certainty of evidence. Two review authors undertook these tasks independently, using predetermined criteria. We contacted study authors for missing data where possible.

MAIN RESULTS

We included four studies with a total of 254 participants. All studies included comparisons between different types of cleansing solutions, and three of these reported our primary outcomes of complete wound healing or change in ulcer size over time, or both. Two studies reported the secondary outcome, pain. One study (27 participants), which compared polyhexamethylene biguanide (PHMB) solution with saline solution for cleansing venous leg ulcers, did not report any of the review's primary or secondary outcomes. We did not identify any studies that compared cleansing with no cleansing, or that explored comparisons between different cleansing techniques. One study (61 participants) compared aqueous oxygen peroxide with sterile water. We are uncertain whether aqueous oxygen peroxide makes any difference to the number of wounds completely healed after 12 months of follow-up (risk ratio (RR) 1.88, 95% confidence interval (CI) 1.10 to 3.20). Similarly, we are uncertain whether aqueous oxygen peroxide makes any difference to change in ulcer size after eight weeks of follow-up (mean difference (MD) -1.38 cm², 95% CI -4.35 to 1.59 cm²). Finally, we are uncertain whether aqueous oxygen peroxide makes any difference to pain reduction, assessed after eight weeks of follow-up using a 0 to 100 pain rating, (MD 3.80, 95% CI -10.83 to 18.43). The evidence for these outcomes is of very low certainty (we downgraded for study limitations and imprecision; for the pain outcome we also downgraded for indirectness). Another study (40 participants) compared propyl betaine and polihexanide with a saline solution. The authors did not present the raw data in the study report so we were unable to conduct independent statistical analysis of the data. We are uncertain whether propyl betaine and polihexanide make any difference to the number of wounds completely healed, change in ulcer size over time, or wound pain reduction. The evidence is of very low certainty (we downgraded for study limitations and imprecision). The final study (126 participants) compared octenidine dihydrochloride/phenoxyethanol (OHP) with Ringer's solution. We are uncertain whether OHP makes any difference to the number of wounds healed (RR 0.96, 95% CI 0.53 to 1.72) or to the change in ulcer size over time (we were unable to conduct independent statistical analysis of available data). The evidence is of very low certainty (we downgraded for study limitations and imprecision). None of the studies reported patient preference, ease of use of the method of cleansing, cost or health-related quality of life. In one study comparing propyl betaine and polihexanide with saline solution the authors do not report any adverse events occurring. We are uncertain whether OHP makes any difference to the number of adverse events compared with Ringer's solution (RR 0.58, 95% CI 0.29 to 1.14). The evidence is of very low certainty (we downgraded for study limitations and imprecision).

AUTHORS' CONCLUSIONS

There is currently a lack of RCT evidence to guide decision making about the effectiveness of wound cleansing compared with no cleansing and the optimal approaches to cleansing of venous leg ulcers. From the four studies identified, there is insufficient evidence to demonstrate whether the use of PHMB solution compared with saline solution; aqueous oxygen peroxide compared with sterile water; propyl betaine and polihexanide compared with a saline solution; or OHP compared with Ringer's solution makes any difference in the treatment of venous leg ulcers. Evidence from three of the studies is of very low certainty, due to study limitations and imprecision. One study did not present data for the primary or secondary outcomes. Further well-designed studies that address important clinical, quality of life and economic outcomes may be important, based on the clinical and patient priority of this uncertainty.

Improving the quality of clinical research on chronic wound infection treatment: expert-based recommendations

OBJECTIVE:

To produce recommendations for the design of reliable and informative clinical investigations in chronic wound infection.

METHOD:

A multidisciplinary panel of international experts from four countries (Italy, UK, Ireland and the US) were involved in a detailed, semi-structured discussion on how to better select and describe a target population, interventions and outcomes, and which infection-related criteria to apply in order to achieve a high-quality trial. Consent among the experts was measured using the Delphi method and GRADE Working Group suggestions. The project was fully supported by AISLeC 2016 (Italian Nursing Society for Wound Care Study).

RESULTS:

In total, 37 recommendations achieved substantial agreement among the experts; 10 concerned the most appropriate description and selection of a target population, four related to interventions and 15 to outcomes. A further eight statements about critical methodological points were approved.

CONCLUSION:

Developing recommendations in a systematic manner through a representative group of experts could generate tools for improving the design of clinical trials in this challenging area.

Publicly Reported Wound Healing Rates: The Fantasy and the Reality

Significance: We compare real-world data from the U.S. Wound Registry (USWR) with randomized controlled trials and publicly reported wound outcomes and develop criteria for honest reporting of wound outcomes, a requirement of the new Quality Payment Program (QPP). Recent Advances: Because no method has existed by which wounds could be stratified according to their likelihood of healing among real-world patients, practitioners have reported fantastically high healing rates. The USWR has developed several risk-stratified wound healing quality measures for diabetic foot ulcers (DFUs) and venous leg ulcers (VLUs) as part of its Qualified Clinical Data Registry (QCDR). This allows practitioners to report DFU and VLU healing rates in comparison to the likelihood of whether the wound would have healed. Critical Issues: Under the new QPP, practitioners must report at least one practice-relevant outcome measure, and it must be risk adjusted so that clinicians caring for the sickest patients do not appear to have worse outcomes than their peers. The Wound Healing Index is a validated risk-stratification method that can predict whether a DFU or VLU will heal, leveling the playing field for outcome reporting and removing the need to artificially inflate healing rates. Wound care practitioners can report the USWR DFU and VLU risk-stratified outcome measure to satisfy the quality reporting requirements of the QPP. Future Directions: Per the requirements of the QPP, the USWR will begin publicly reporting of risk-stratified healing rates once quality measure data have met the reporting standards of the Centers for Medicare and Medicaid Services. Some basic rules for data censoring are proposed for public reporting of healing rates, and others are needed, which should be decided by consensus among the wound care community.

Sustained antimicrobial activity and reduced toxicity of oxidative biocides through biodegradable microparticles

The spread of antibiotic-resistant pathogens requires new treatments. Small molecule precursor compounds that produce oxidative biocides with well-established antimicrobial properties could provide a range of new therapeutic products to combat resistant infections. The aim of this study was to investigate a novel biomaterials-based approach for the manufacture, targeted delivery and controlled release of a peroxygen donor (sodium percarbonate) combined with an acetyl donor (tetraacetylethylenediamine) to deliver local antimicrobial activity via a dynamic equilibrium mixture of hydrogen peroxide and peracetic acid. Entrapment of the pre-cursor compounds into hierarchically structured degradable microparticles was achieved using an innovative dry manufacturing process involving thermally induced phase separation (TIPS) that circumvented compound decomposition associated with conventional microparticle manufacture. The microparticles provided controlled release of hydrogen peroxide and peracetic acid that led to rapid and sustained killing of multiple drug-resistant organisms (methicillin-resistant Staphylococcus aureus and carbapenem-resistant Escherichia coli) without associated cytotoxicity in vitro nor intracutaneous reactivity in vivo. The results from this study demonstrate for the first time that microparticles loaded with acetyl and peroxygen donors retain their antimicrobial activity whilst eliciting no host toxicity. In doing so, it overcomes the detrimental effects that have prevented oxidative biocides from being used as alternatives to conventional antibiotics.

STATEMENT OF SIGNIFICANCE

The manuscript explores a novel approach to utilize the antimicrobial activity of oxidative species for sustained killing of multiple drug-resistant organisms without causing collateral tissue damage. The results demonstrate, for the first time, the ability to load pre-cursor compounds into porous polymeric structures that results in their release and conversion into oxidative species in a controlled manner. Until now, the use of oxidative species has not been considered as a candidate therapeutic replacement for conventional antibiotics due to difficulties associated with handling during manufacture and controlling sustained release without causing undesirable tissue damage. The ultimate impact of the research could be the creation of new materials-based anti-infective chemotherapeutic agents that have minimal potential for giving rise to antimicrobial resistance.