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Relevance of a Health Technology Assessment report: antimicrobial wound dressings for diabetic foot chronic wounds with local infection

Naomi Fearns, Susan Myles, Karen Macpherson, Alison Rodgers, Lynne Watret

This article discusses the challenges of implementing recommendations of a recent Health Technology Assessment report highlighting available evidence for the use of antimicrobial wound dressings (AWDs). Despite a lack of clear evidence to support their use, they are routinely used as part of management plans in local diabetic foot wound infection. Therefore, it would suggest that clinical judgement views there is a role for the continued use of AWDs. If so, in the interest of patient safety, there is a need for clear guidance on when to initiate, the duration of use and when to stop. The report provides recommendations that reflect this apparent disparity between theory and practice. The authors seek to stimulate discussion in this challenging area and to explore if there is a place for AWDs or are there alternative methods of preventing and treating local wound infection?

Healthcare Improvement Scotland produced the Health Technology Assessment (HTA) Report 13 on the use of antimicrobial wound dressings for chronic wounds, which has recently been published (Healthcare Improvement Scotland, 2015). The HTA report provides a great deal of information, which would be impossible to cover in one article. However, for the purposes of this discussion, the HTA recommendations and consensus statements will be highlighted for the attention of The Diabetic Foot Journal readership, to open up discussion on this important area.

The overarching research questions addressed in the HTA report were:

  • What is the clinical and cost effectiveness of different antimicrobial wound dressings (AWDs) and their safety, compared with other dressings and techniques, for treating localised wound infection in chronic wounds in adults?
  • What are the patient and organisational issues associated with the use of different AWDs in adult patients with chronic wounds?

The report was restricted to reviewing in vivo studies of chronic diabetic foot ulcers, pressure ulcers, leg ulcers and wounds healing by secondary intention. The three main chronic ulcer types constituted 90% of wounds. In vitro studies were excluded, as the focus of the work was on patient outcomes and consideration of the results on vitro studies would not remove uncertainties in the findings.

It is not within the remit of this article to discuss the roles of systemic antimicrobials or the multidisciplinary diabetic foot team.

Product choices consisted of AWDs listed in Part 5 of the British National Formulary (2015), which included iodine, silver, honey, polyhexamethlene biguanide (PHMB), dialkylcarbamoyl chloride (DACC) and glucose oxidase/lactoperoxidase.

The main finding from the clinical and cost-effectiveness aspect of the HTA was that there is insufficient clinical evidence to support the use of AWDs to treat local infection in chronic wounds. Despite this, they are currently used for this indication in NHS Scotland. This HTA has highlighted that the approach used varies between and within NHS health boards. There are no clear starting and stopping rules for AWDs, and the range of AWDs available for clinicians to use varies. This inconsistency can be frustrating for staff, and can be an additional burden to patients. There is a need for a more consistent approach until the clinical evidence becomes more informative.

This view raises a challenge since respondents in the HTA noted that they included the use of AWDs for both compromised and non-comprised perfusion in the management of diabetic foot ulcers.

“Chronic wounds often contain necrotic or sloughy tissue, which can harbour bacteria and act as a barrier to healing,” explained Vowden and Vowden (2011). Do the HTA (2015) findings present an argument for greater research into the role of safe and cost-effective alternative methods of reducing bacterial bioburden, which may replace or complement the use of AWDs for diabetic foot ulcers?

In light of this, rather than a major paradigm shift and opting for a ‘ban’ on the use of AWDs, perhaps the report may well support a view similar to Verheij (2009); namely to identify the small group of patients who really need antibiotic treatment and to explain, reassure and educate the large group of patients who do not.

The issues explored in the Health Technology Assessment Report 13 (Health Improvement Scotland, 2015) were facilitated by means of expert panel views; synthesis of quantitative and qualitative literature; clinician questionnaire; and focus group/patient interviews.

Specialist podiatrists and nurses were included in the HTA expert group. A clinician questionnaire was completed by 263 respondents. The majority of respondents were district nursing staff (31.9%) with podiatrists accounting for 20.5%.

Respondents’ clinical activity highlighted that the majority of patients were managed in primary care with 20% attending specialist outpatient clinics (i.e. podiatry, diabetic multidisciplinary teams and leg ulcer clinics).

Discussion
Dressing choice for diabetic foot ulcers can be challenging due to the complexity of wound types (perfusion, tissue type, deformity etc). It is not within the scope of this article to enter into discussion about wound assessment, however, Botros et al (2010) stressed the importance of completing a comprehensive diabetes assessment. Sood et al (2014) also stated that “wound characteristics must be addressed” before choosing a wound dressing.

“Dressing choice will generally change as the wound characteristics change during healing,” stated Bergin et al (2012). This may result in variations in practice, dependent on the knowledge base of clinicians and patient choice. However, it is important to ensure products are used appropriately and cost effectively (Jeffcoate et al, 2009). Dressing choice is further complicated since there is “little evidence to support the choice of any one dressing or wound application in preference to any other in attempts to promote healing of chronic ulcers of the foot in diabetic patients” (Apelqvist et al, 2012). If an AWD is considered appropriate, the clinician should be aware that “an antimicrobial dressing may reduce the level of bacteria at the wound surface, but will not eliminate a spreading infection” (Scottish Government, 2014). An active diabetic foot ulcer should, therefore, be referred to the multidisciplinary foot team (NICE, 2015).

One podiatrist noted: “When dealing with high-risk diabetic wounds, which can easily become infected with the risk of amputation (especially if that person has had a previous amputation), there is always the thought at the back of your mind that it’s safer to use antimicrobials to prevent infection as the possible consequences will be disastrous” (HTA, 2015). There did not appear to be agreement on what would prompt the process of prescribing AWDs for prophylaxis.

If the assumption is that AWDs will continue to be used, a rationale for use is required to support clinicians in safe practice. Chadwick (2013) suggested that “topical antimicrobials may be beneficial in certain situations”, for example, “where there are concerns regarding reduced antibiotic tissue penetration” to reduce the bacterial load. HTA (2015) respondents noted that in treating chronic wounds, they limited their use of AWDs to wounds showing signs and symptoms of infection. Botros et al (2010) recommended that ulcers should be evaluated at each visit for clinical signs of infection with appropriate follow-up microbiology if required.

There is, therefore, a need for education to ensure that signs and symptoms of wound infection in diabetic foot ulcers are clearly understood and this is differentiated and recognised between chronic wound types (European Wound Management Association, 2015, TRIEPodD-UK (2012).

 Duration of treatment, number of interventions and volume required should be taken into account for safe prescribing. This will prevent ongoing use of an AWD when not required, or the risk of potential side effects, which can result in delayed healing or desiccation to underlying structures, such as tendon and bone. This is an area that requires greater discussion.

This journal’s readership will be familiar with the much quoted ‘Vulcan study’ on the use of silver dressings on leg ulcers (Michaels et al, 2009). There was some debate that the study “did not use silver as recommended” (Leaper and Drake, 2011). There are a number of reviews on the use of silver dressings that have highlighted the lack of robust evidence to support their routine use (Botros et al, 2010; Storm-Versloot et al, 2010; Game et al, 2012; Health Improvement Scotland, 2012).

The Vulcan Study demonstrated that there is “little to be gained in using AWDs on wounds with no signs of clinical infection” (Scottish Government, 2014). Avoiding the use of silver may increase the chance of the clinician migrating to routine use of other types of AWDs. One podiatrist noted: ‘I feel that silver dressings when used appropriately can be very useful in diabetic foot ulcers. It is very unfortunate that there is very little evidence for their use, therefore, their use is restricted.’ (HTA 2015)

Clinicians’ responses from the report questionnaire noted that for diabetic foot ulcers — irrespective of compromised perfusion or not — iodine, silver and honey were most frequently chosen (Figure 1). This demonstrates that the respondents in this study continue to use AWDs, in the management of the diabetic foot ulcers.

Recommendations
The recommendations, consensus and non-consensus statements provide opportunities for discussion and collaborative working across all specialties to support cost-effective, safe, patient-centred care. The eight recommendations (Table 1) are relevant to all chronic wound ulcers. Greater detail regarding the literature review on diabetic foot ulcers and consensus statements are available in the HTA (2015).

Statements where consensus was reached
Consensus was reached that AWDs should be avoided in the absence of signs of clinical infection. Internationally recognised tools, such as Wound Bed Preparation and TIME, support a consistent systematic approach to wound assessment (Falanga, 2001; Schultz and Dowsett 2012; Ousey and Atkin, 2013). Stratifying chronic wounds with use of grading tools to promote a common language and inform care pathways is recommended. NICE (2015) has recommended the use of grading tools, such as SINBAD or TEXAS, for diabetic foot.

Where consensus could not be reached
There were two main themes where consensus could not be reached (Table 2). This demonstrated overall, that there is consensus on clinicians’ perception on what we should do, but conversely there was a lack of consensus on the detail of how to do it, in terms of which product should be used, when and for how long. This provides an opportunity to identify where consensus statements can be developed to provide a focus for further research and team work.

Challenges of making appropriate product choices
A wide range of AWDs are available, with each category having different levels of antimicrobial activity. Since the clinician is either prescribing or influencing a prescribing decision, it is essential that there is an understanding of the actions of the antimicrobial agent (Gottrup et al, 2013). The rationale why a particular clinician chooses to use an AWD in preference to an alternative method of reducing bacterial bioburden (e.g. debridement) should be consistent and clear, regardless of the patient environment or circumstances.

All AWDs, including the ‘preferred’ choices, iodine, silver and honey (Figure 1), have many presentations with base or ‘carrier’, such as a gel, foams or alginate. A clinical decision is, therefore, required to establish which presentation will be the most effective, to maximise interaction at the wound bed  and  manage different levels of exudate or manage odour or pain (Wounds UK, 2011) with “specific products chosen to reflect the overall treatment of the wound” (Wound Care Alliance, 2011).

Conversely, it is also crucial to ensure application of a product does not contribute to pain, odour and exudate due to the carrier or active antimicrobial.  These factors were also highlighted in the patient issues section of the HTA. These can have a major impact on patients’ wellbeing, if left uncontrolled.

The presence of slough, necrosis, exudate and tracking channels on the wound also have to be taken into account when a dressing choice is being made.

Some AWDs have the ability to debride the wound, as well as manage different levels of exudate. A sound rationale for choice of debridement “can be generated via the diagnosis of different kinds of tissue types and bioburden which cover the wound bed, the state of the wound edges and the periwound skin” (Strohall et al, 2013).

“There are a number of techniques for actively debriding a wound,” according to Wounds UK (2013). Respondents in the study questionnaire gave examples of Debrisoft® (Activa Healthcare), Versajet® (Smith & Nephew) and superabsorbers, which they used as alternatives to AWDs. It is essential that the most suitable choice of debridement is made for a particular wound, and the clinician has the competency skills to carry out the procedure (TRIEPodD-UK, 2012)

Duration of product use
The HTA identified consensus on “2-week” challenges of AWDs when a decision is made to commence. This should not be interpreted to mean that only 2 weeks is permitted when using an AWD, but rather “if used, there should be regular review of the efficacy of an antimicrobial wound dressing and it should be stopped after 2 weeks if there is limited or no benefit” (Scottish Government, 2014).  The HTA (2015) concurred with this view, with a consensus on discontinuing AWDs if symptoms of localised infection had been resolved; continuing for a further 2 weeks if symptoms are resolving; and a review management plan if symptoms were static or deteriorating.

Conclusion
The HTA produced both evidence-based and consensus recommendations to support best practice when AWDs are being considered. This also highlighted the need for robust research, as well as consideration of other factors that affect patient wellbeing when choosing a product.

Comments by some report respondents included the view that there was “overuse” and “inappropriate use” of AWDs. No clinician intentionally sets out to cause harm, however, variations in practice may indicate differences in views between healthcare professionals as to what is an appropriate treatment.

An algorithm or pathway, suitable for all chronic wound types, on the management of local wound infection, has been included as a consensus recommendation. An agreed framework could help inform content of local wound formularies and identify necessary requirements if there are any gaps in delivery of education or organisational changes.

The HTA report provides an opportunity  to clarify ‘appropriate use’ and provide robust guidance on the use of AWDs and alternative products to reduce the bacterial bioburden.

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