Chronic wounds: advanced wound dressings and antimicrobial dressings

Evidence from the full NICE guideline: Diabetic foot problems

Alginate dressings versus foam dressings: 1 low‑quality randomised controlled trial (RCT: n=60) found there was no statistically significant difference between complete ulcer healing at 8 weeks for diabetic foot ulcers treated with an alginate dressing or a foam dressing.

Hydrofibre dressings versus saline gauze dressings: 2 very low‑quality RCTs (n=51) found there was no statistically significant difference between ulcer healing, the number of adverse events or the number of complications for diabetic foot ulcers treated with a hydrofibre dressing or a saline gauze dressing.

One very low‑quality RCT (n=20) found diabetic foot ulcers treated with a hydrofibre dressing healed significantly faster than those treated with a saline gauze dressing (mean healing time 127 days compared with 234 days, p<0.001).

Hydrocolloid dressings versus alginate dressings: 1 low‑quality RCT (n=134) found there was no statistically significant difference between ulcer healing, ulcer healing time, number of adverse events or number of complications for diabetic foot ulcers treated with a hydrocolloid dressing or a calcium alginate dressing.

Hydroactive dressings versus hydrophilic dressings: 1 very low‑quality RCT (n=40) found there was no statistically significant difference between ulcer healing time or the change in ulcer size for diabetic foot ulcers treated with a hydroactive dressing or a hydrophilic dressing.

Other dressings: 1 moderate‑quality RCT (n=229) found there was no statistically significant difference between ulcer healing, healing time, number of amputations, adverse events or complications for diabetic foot ulcers treated with a hydrofibre dressing, iodine‑impregnated dressing or a non‑adherent dressing.

One moderate‑ to low‑quality RCT (n=50) found there was no statistically significant difference between adverse events and ulcer cure rates for people treated with soft silicone dressing or a Vaseline gauze dressing over 12 weeks.

See the diabetic foot problems, appendix F and appendix I for more details.

Conclusion: The guideline development group concluded that evidence surrounding different types of dressings for diabetic foot ulcers was often limited or inconclusive. The group proposed that more RCTs should be undertaken to monitor and evaluate the cure rates of foot ulcers resulting from diabetes, rates and extent of amputation (major or minor), health‑related quality of life, adverse events and hospital admission rates and length of stay. However, alternative methodologies may also be considered in the case of treating a complex wound.

The guideline development group considered that patient decisions, dressing availability, wound severity and factors such as infection control were all issues that contribute to decisions about the choice of dressing. It therefore considered it was inappropriate to recommend specific types of dressing. The group did however acknowledge that the lowest cost dressings may not necessarily be the most appropriate dressings for patient needs and therefore reflected this in the recommendations.

Cochrane overview: Dressings for treating foot ulcers in people with diabetes

This Cochrane overview (Wu et al. 2015) summarised data from 13 systematic reviews of 17 RCTs looking at the effectiveness of dressings for healing foot ulcers in people with diabetes. Collectively, the trials compared 10 types of dressings with each other, making a total of 37 comparisons (11 supported by direct data and 26 supported by indirect data only). All the included reviews were considered to be of moderate to high quality.

For comparisons informed in part by direct data, the reviews reported no clear evidence of a difference between the following dressings in terms of wound healing:

Hydrogel dressings were found to be statistically significantly more effective than basic wound contact dressings for complete wound healing (3 RCTs, n=198: direct data, relative risk [RR] 1.80, 95% confidence interval [CI] 1.27 to 2.56: low‑quality evidence), as were foam dressings (2 RCTs, n=49: direct and indirect data, odds ratio [OR] 4.32, 95% CI 1.56 to 9.85: very low‑quality evidence). Foam dressings were more effective than alginate dressings (2 RCTs, n=50: direct and indirect data, OR 3.61, 95% CI 1.30 to 8.30: very low‑quality evidence).

Conclusion: The Cochrane review concluded that there is currently no robust evidence that any advanced dressing type is more effective than basic wound contact dressings for healing foot ulcers in people with diabetes. The authors noted that there is imprecision around the estimates for all the comparisons because few RCTs were available and these trials generally had small numbers of participants. Also, in the 3 comparisons in which direct evidence of a difference was reported, the evidence was considered to be low or very low quality. Therefore, the findings are reported to be uncertain and not optimal in terms of informing practice.

It has been suggested that different dressings may be more appropriate for specific wound states or stages of healing, implying that complete healing may not be an appropriate treatment aim for all interventions. For example, foam and alginate products may be used to manage periods of heavy exudate, while antimicrobial dressings may help to resolve infection (see the wound management products section of the BNF). Most of the RCTs discussed in the Cochrane review focused on wound healing as the primary outcome and presented relatively few data on secondary outcomes. The authors noted that more research is needed on benefits that may be achieved with different types of dressings and how additional outcomes of importance to decision‑makers (including service users) such as exudate management, resolution of infection and adverse effects may best be measured. They concluded that practitioners may want to consider the unit cost of dressings, their management properties and the person's preference when choosing dressings.

Evidence from the full NICE guideline: Management of pressure ulcers

Hydrocolloid dressings versus gauze dressings: In 4 RCTs (273 ulcers), hydrocolloid dressings were found to be statistically significantly more effective than gauze dressings in terms of the proportion of pressure ulcers completely healed (RR 2.53, 95% CI 1.70 to 3.78: low‑quality evidence). Benefits appeared to be more pronounced in people with spinal cord injury than in the general population. Gauze dressings caused significantly more harm than hydrocolloid dressings in terms of skin irritation (1 RCT, 100 ulcers: OR 0.11, 95% CI 0.03 to 0.44: low‑quality evidence), pain at dressing removal (1 RCT, 34 ulcers: OR 0.09, 95% CI 0.02 to 0.45: low‑quality evidence) and discomfort (1 RCT, 34 ulcers: OR 0.07, 95% CI 0.02 to 0.32: low‑quality evidence). Mortality was statistically significantly higher in the gauze dressings group (3 RCTs, 156 ulcers: RR 0.24, 95% CI 0.07 to 0.89: very low‑quality evidence).

Hydrocolloid dressings versus foam dressings: There was no statistically significant difference between hydrocolloid dressings and foam dressings for the proportion of people whose ulcers were completely healed (3 RCTs, 157 ulcers: very low‑quality evidence), mortality (1 RCT, 60 ulcers: very low‑quality evidence) or adverse events (2 RCTs, 100 ulcers: very low‑quality evidence).

Hydrocolloid dressings versus polyurethane film dressings: There was no statistically significant difference between hydrocolloid dressings and polyurethane film dressings for ulcer healing outcomes (very low‑quality evidence). Mean comfort and odour scores were marginally better in the polyurethane dressings group (1 RCT, 72 ulcers: mean differences −0.20, 95% CI −0.33 to −0.07 and −0.40, 95% CI −0.64 to −0.16 respectively: very low‑quality evidence).

Hydrocolloid dressings versus hydrogel dressings: Hydrogel dressings were statistically significantly more effective than hydrocolloid dressings for the proportion of pressure ulcers completely healed in 1 RCT (129 ulcers: RR 0.46, 95% CI 0.25 to 0.84: very low‑quality evidence). The guideline development group discussed that in clinical practice hydrogel dressings and hydrocolloid dressings were not necessarily an appropriate comparison because there would be different clinical indications for each dressing.

Hydrocolloid dressings versus alginate dressings: In 1 RCT (110 ulcers), there was no statistically significantly difference between hydrocolloid and alginate dressings for the proportion of people whose ulcers were 40% healed (very low‑quality evidence). However, the mean percentage reduction in ulcer area was higher in the alginate group (mean difference −26.50%, 95% CI −42.38% to −10.62%: low‑quality evidence). The guideline development group considered that comparing alginate dressings with hydrocolloid dressings was not a relevant comparison because they are used in clinical practice for different clinical indications.

Foam dressings versus gauze dressings: In 2 RCTs (74 ulcers), there was no statistically significant difference between gauze and foam dressings in terms of the proportion of people whose ulcers were completely healed and reduced mortality (very low‑quality evidence).

Foam dressings versus hydrogel dressings: In people undergoing palliative care, there were no statistically significant differences between foam and hydrogel dressings in terms of the proportion of ulcers completely healed (1 RCT, 38 ulcers: very low‑quality evidence) and most other outcomes assessed (very low‑quality evidence).

Polyurethane film dressings versus gauze dressings: Polyurethane film dressings were statistically significantly more effective than gauze dressings for the proportion of pressure ulcers completely healed (2 RCTs, 53 ulcers: OR 0.08, 95% CI 0.02 to 0.31: low‑quality evidence).

Hydrogel dressings versus gauze dressings: No statistically significant differences were found between hydrogel and gauze dressings (very low‑quality evidence).

Alginate dressings versus silver‑containing alginate dressings: There were no statistically significant differences between alginate and silver‑containing alginate dressings (very low‑quality evidence).

See the pressure ulcers, appendix I and appendix G for more information on the evidence to support the use of wound dressings for managing pressure ulcers in adults and children.

Economic analyses: The NICE guideline development group considered 3 economic analyses that included gauze dressings. None of these studies found gauze dressings to be cost effective. Comparators included alginate, hydroactive dressings and hydrocolloid dressings.

Regarding other dressings, 11 economic studies were considered but the guideline development group did not consider that the economic evidence was strong enough to identify a cost‑effective type of dressing. They considered unit costs relevant to the UK, but noted that the major resource implications come from the frequency that each dressing requires changing. This is likely to depend on a range of factors, such as location of the ulcer, the amount of exudate and patient acceptability. The frequency of dressing change can also have a substantial impact on quality of life.

Conclusion: Overall, the quality of clinical evidence was graded low to very low. Most of the studies had very serious limitations. In the studies that found a clinical effect, most of the results had serious to very serious imprecision, indicating high uncertainty in the results. The guideline development group noted that there were some problems with the comparisons in studies, such as non‑clinically relevant comparisons and dressings not used in current UK clinical practice.

The guideline development group found there was little clinical benefit of gauze dressings and these are not recommended for pressure ulcers. There are adverse events associated with gauze dressings that the guideline development group identified as important, such as increased pain at dressing removal, skin irritation and discomfort.

The guideline development group did not consider that the evidence allowed for a recommendation to be made about the use of a specific type of dressing. This was because of the lack and quality of evidence, as well as the importance of considering the function of the dressing and specific patient factors. The group emphasised that the effectiveness of each dressing would depend on the type of pressure ulcer and, therefore, chose to recommend a dressing that promotes the optimum healing environment, rather than a specific type of dressing.

The guideline development group considered it was important to take into account the following factors when choosing a dressing:

In addition, it was noted that a wound can deteriorate because of dressing changes and this is a specific issue with regards to sacral ulcers that are likely to become frequently soiled. The frequency of dressing changes was also noted to affect the healing of a wound, and can be detrimental to the effectiveness of the dressing.

Cochrane review: Hydrogel dressings for treating pressure ulcers

This Cochrane review (Dumville et al. 2015a) included 11 RCTs (n=523), including 3 that were not in the NICE guideline on pressure ulcers. The RCTs compared hydrogel dressings with 6 different comparators, including basic wound contact dressings, hydrocolloid dressings, other hydrogel dressings and foam dressings. However, the trials were poorly reported so only limited data were available for analysis and no meta‑analyses could be performed.

When data were available, there was no evidence of a statistically significant difference between hydrogel and alternative dressings in terms of complete wound healing (the primary outcome) or adverse events (low‑ or very low‑quality evidence).

The included RCTs were small (n=10 to n=143). Therefore, they were considered to be statistically underpowered to detect treatment differences, if they existed, and the findings were imprecise. In addition, the trials had short follow‑up times (3 to 12 weeks) and were at high or unclear risk of bias.

Conclusions: The authors concluded that the systematic review did not find reliable evidence that hydrogel dressings either increase or decrease the healing of pressure ulcers compared with other dressings. They noted that practitioners may therefore elect to consider other characteristics such as costs and symptom management properties when choosing between dressings.

Cochrane review: Alginate dressings for pressure ulcers

This Cochrane review (Dumville et al. 2015b) included 6 RCTs (n=336), including 3 that were not in the NICE guideline on pressure ulcers. The RCTs compared alginate dressings with 6 other interventions, including hydrocolloid dressings and silver‑containing alginate dressings. Overall, the body of literature was very limited: each comparison was informed by only 1 RCT.

Few data were available for the primary outcome, complete wound healing: 1 small RCT (n=36) found no evidence of a statistically significant difference between 2 brands of alginate dressings (very low‑quality evidence). One study (n=110: also discussed in NICE's full guideline on pressure ulcers, see earlier for details) reported a statistically significant reduction in ulcer area and the mean number of dressing changes with alginate dressings followed by hydrocolloid dressings compared with hydrocolloid dressings alone (very low‑quality evidence). There was no evidence of a difference between the groups in any other secondary outcomes reported, including adverse events and wound infection.

The RCTs included in the Cochrane review were small and considered to be underpowered to detect differences between the dressings, if they existed. Follow‑up times were short (4 to 8 weeks in 5 RCTs and unclear in the sixth RCT) and the evidence was of low or very low‑quality and at risk of bias. The authors also noted that there may be comparisons that are important to decision‑makers for which trials have not been conducted.

Conclusions: The authors concluded that the relative effects of alginate dressings compared with alternative treatments are unclear. Decision‑makers may wish to consider aspects such as cost of dressings and the wound management properties offered by each dressing type, for example, exudate management.

Meta‑analysis: Dressings for preventing pressure ulcers

This meta‑analysis (Huang et al. 2015) included 35 RCTs or quasi‑RCTs (n=5,401), 30 of which compared the number or incidence of pressure ulcers in people receiving standard care plus dressings with those in people receiving standard care alone. The other 5 trials compared dressings without a control group and were analysed separately.

Compared with standard care alone, the risk of developing pressure ulcers was statistically significantly reduced in people who used hydrocolloid dressings (7 trials, n=494: RR 0.20, 95% CI 0.12 to 0.36, p<0.001), foam dressings (11 trials, n=2,090: RR 0.17, 95% CI 0.12 to 0.26, p<0.001) and film dressings (3 trials, n=307: RR 0.50, 95% CI 0.32 to 0.76, p=0.001). Statistically significantly fewer people in the foam dressings group developed pressure ulcers compared with the hydrocolloid dressings group (4 RCTs, n=467: RR 0.16, 95% CI 0.07 to 0.38, p<0.001).

The included trials have limitations. For example, a number were sponsored by manufacturers, variables (age, comorbidities, medications, length of stay, resources and the extent that best practice to prevent pressure ulcers was implemented) were often not controlled, and it is unclear whether participants in the dressing and control groups were at similar risk of developing pressure ulcers. Also, study durations and follow‑ups were short, meaning the number of pressure ulcers developed may have been underestimated. Pressure ulcers commonly occur on the sacrum, coccyx and heels, and these are the most challenging areas to protect because dressings tend to slip, bunch up or get soiled. However, they were not evaluated in the studies.

Conclusions: Hydrocolloid, film and foam dressings were found to prevent pressure ulcers compared with standard care. However, although the authors stated that the methodological quality of the included studies was assessed using the Cochrane Collaboration tool and the risk of bias is reported, the quality of the evidence is not graded. Also, the authors noted that dressings do not replace best practices, such as turning and repositioning, skin care, good nutrition and continence management. In people who are at risk of pressure ulcers, NICE guidance on preventing and managing pressure ulcers recommends repositioning, ensuring nutrition and hydration are adequate, using pressure redistribution devices and considering barrier creams for preventing pressure ulcers.

Evidence from the full SIGN guideline: Management of chronic venous leg ulcers

In the SIGN guideline, recommendations on non‑adherent dressings and compression bandaging are based on a 2006 Cochrane review (Palfreyman et al. 2006) that has now been superseded by the Cochrane reviews below. The 2006 Cochrane review identified 42 RCTs (n=3,001) in which simple non‑adherent dressings were compared with hydrocolloid (9 RCTs, n=928), hydrogel (2 RCTs, n=134) and foam dressings (3 RCTs, n=253). The evidence found did not suggest that hydrocolloid dressings are more effective than simple non‑adherent dressings used beneath compression bandages. There was insufficient evidence for other comparisons. No evidence was identified on the effectiveness of different dressings in people unable to tolerate multilayer compression bandaging.

Recommendations on silver dressings are based on a Cochrane review (Vermeulen et al. 2007) and the later VULCAN trial (Michaels et al. 2009). The Cochrane review included 3 RCTs (n=847) comparing silver dressings with foam or alginate dressings, or best practice for treating infected wounds (not only venous leg ulcers). Two RCTs (n=129 and n=99) showed no difference between products and 1 reported statistically significantly faster healing rates but did not report complete healing (n=619). All 3 RCTs were small and of short duration. They could not be combined in a meta‑analysis because they considered different wounds, dressings and end points.

VULCAN (n=213) was a pragmatic, publicly funded RCT, which compared a range of silver dressings with a range of non‑adherent dressings (in addition to standard compression) and found no statistically significant differences in median time to complete healing or healing rates at 3, 6 and 12 months. See below for more information on this study.

Conclusion: SIGN concluded that simple non‑adherent dressings are recommended in the management of venous leg ulcers; silver dressings are not.

Cochrane review: Alginate dressings for venous leg ulcers

This Cochrane review (O'Meara et al. 2015) included 5 RCTs (n=295). One RCT compared different alginate dressings (n=20), 3 compared alginate and hydrocolloid dressings (n=215), and 1 compared alginate and simple non‑adherent dressings (n=60). No statistically significant differences were found between the groups for any comparison, for any healing outcome. Adverse event profiles were generally similar between treatment groups. The overall risk of bias was high for 2 RCTs and unclear for 3 RCTs and the quality of the evidence was reported to be very low.

Conclusions: The authors concluded that there is no evidence to suggest that there are any differences in terms of wound healing between different alginate dressings, or between alginate dressings and hydrocolloid dressings, or alginate dressings and non‑adherent dressings. Good‑quality evidence is required from well‑designed RCTs before any definitive conclusions regarding the efficacy of alginate dressings (or other dressings included in the Cochrane review) for managing venous leg ulcers can be drawn and recommendations about their use can be made.

Cochrane review: Foam dressings for venous leg ulcers

This Cochrane review (O'Meara and Martyn-St James 2013) included 12 RCTs (n=1,023) reporting 14 comparisons. No statistically significant differences were found between:

Six RCTs were considered to be at overall high risk of bias, and the remaining 6 RCTs were considered to be at overall unclear risk of bias. The evidence was generally of low quality. The exception to this was for the outcome of complete healing for the comparison of foam and hydrocolloid dressings, where the evidence was of moderate quality.

Conclusion: The authors stated that there is no evidence to suggest that foam dressings are better or worse than any other primary wound contact dressings for healing venous leg ulcers when applied beneath compression systems. Good‑quality evidence from well‑designed RCTs is needed before definitive conclusions about the efficacy of foam dressings (or other dressings included in the Cochrane review) for managing venous leg ulcers can be drawn, and recommendations about their use can be made.

Cochrane review: Topical agents or dressings for pain in venous leg ulcers

In this Cochrane review (Briggs et al. 2012) no trials were identified comparing different dressings for relieving pain in venous leg ulceration.

The Cochrane review found 2 RCTs (n=470) that evaluated ibuprofen slow‑release foam dressings for persistent venous leg ulcer pain. In 1 RCT (n=348), compared with local best practice, statistically significantly more participants in the ibuprofen dressing group achieved more than a 50% reduction in pain between day 1 and day 5 (RR 1.63, 95% CI 1.24 to 2.15; number needed to treat 6, 95% CI 4 to 12). In the second RCT (n=122), compared with an identical non‑ibuprofen foam dressing, there was no statistically significant difference in the proportion of participants experiencing slight to complete pain relief on the first evening of treatment. Limited data were available to assess healing rates or adverse events.

Conclusions: The authors concluded that there is some evidence that foam dressings containing ibuprofen provide pain relief for some people with painful venous leg ulcers. However, they state that variability in the pain assessment method and the reporting of pain outcomes across trials, coupled with the potential bias associated with unblinded outcome assessment, makes interpretation of the current evidence base for topical ibuprofen in the management of chronically painful leg ulcers difficult. Also, the release of ibuprofen into the wound bed depends on the presence of wound exudate and, therefore, these dressings are not suitable for people with venous leg ulcers that that have low levels of, or no, exudate.

Chronic venous ulcers: a comparative effectiveness review of treatment modalities

The Agency for Healthcare Research and Quality (AHRQ 2014) in the USA has systematically reviewed the literature on the effectiveness and safety of advanced wound dressings, systemic antibiotics and surgical interventions in people with chronic venous leg ulcers. One of the key questions in the review considered the benefits and harms of dressings that regulate wound moisture with or without active chemical, enzymatic, biologic or antimicrobial components in conjunction with compression systems compared with compression systems alone.

In terms of the proportion of ulcers healed, no statistically significant difference was found between the groups for:

Definitive conclusions could not be drawn for these comparisons because of limitations in study quality, imprecise estimates and heterogeneity in study designs (insufficient strength of evidence).

Hydrocolloid dressings were not found to be statistically significantly more effective than compression alone in terms of the proportion of chronic venous ulcers healed. The results from the 3 RCTs (n=361) addressing this comparison were imprecise and subject to some bias (low strength of evidence).

Silver dressings did not statistically significantly improve wound healing compared with non‑silver dressings (VULCAN trial, n=213; moderate strength of evidence). See below for more information on silver dressings.

Conclusions about the effects of advanced wound dressings on pain or quality of life could not be made due to inconsistent reporting of these outcomes. Also, conclusions about the effect of advanced wound dressings on the condition of the wound bed could not be made because of heterogeneity in study designs and inconsistency in evaluating and reporting on the condition of the wound bed.

Evidence was lacking on the effects of advanced wound dressings on maceration, contact dermatitis, venous or arterial impairment and cellulitis.

Conclusion: The AHRQ concluded that there was a general lack of well‑designed, well‑controlled studies, as well as a lack of a standard case definition, or approaches to managing confounders and interactions. For advanced wound dressings, there was no impact on wound healing when compared with compression therapy alone.

Meta‑analyses: Silver dressings for venous leg ulcers (Greer et al. 2013 and Leaper et al. 2013)

A study by Greer et al. (2013) evaluated the benefits and harms of advanced wound care therapies for non‑healing diabetic, venous and arterial ulcers. Most of the comparisons have been covered by the systematic reviews outlined above but the paper includes a meta‑analysis of 2 RCTs (including VULCAN; n=255) on silver dressings for venous leg ulcers. This found that there was no statistically significant difference between silver dressings and non‑silver dressings. The RCTs were reported to be fair quality using a modification of the Cochrane approach to determining risk of bias and a scale of good, fair or poor.

A second, manufacturer‑sponsored study by Leaper et al. (2013) evaluated the effects of a specific brand of silver dressing (Biatain Ag) on hard‑to‑heal venous leg ulcers (defined as clinical signs of infection [exudates, pain, discoloration and odour] and/or less than 20% ulcer size reduction over 4 weeks). The study included 4 RCTs (n=1,055), some of which included people with pressure ulcers, diabetic ulcers or arterial ulcers. Leaper et al. (2013) excluded people without venous or mixed aetiology leg ulcers and those who had been treated with an active comparator or gauze (n=370) from the meta‑analyses.

Leaper et al. (2013) found that, in meta‑analyses of data from the 4 RCTs (n=685) compared with control (foam or alginate dressings, or local best practice including passive and non‑antimicrobial dressings), silver dressings statistically significantly:

The meta‑analysis has many limitations that affect its interpretation. For example, it did not report the quality of the evidence or assess the risk of bias, only 1 brand of silver dressings was assessed and, as well as sponsoring the study, the manufacturer of that brand of dressing was involved in authoring the paper. Also, complete data were not reported for all outcomes (for example, numbers of patients and 95% confidence intervals).

Conclusion: The authors noted that the included RCTs on silver dressings are heterogeneous with study designs and populations varying considerably (for example, age, ulcer size, type of ulcer and presence of infection). Also, the RCTs may have been too short to reliably assess complete healing, the outcome which is likely to be most relevant to patients. They concluded there is evidence that silver dressings can improve outcomes at 4 weeks when used for treating hard‑to‑heal venous leg ulcers.

More information on the evidence for silver dressings is available in the infected wounds section of this evidence summary.

Cost effectiveness of silver dressings for venous leg ulcers

Economic modelling of data from the VULCAN trial found that silver dressings were associated with an incremental cost of £97.85 compared with control dressings when used for treating venous leg ulcers. The additional cost of silver dressings was partly due to an increased cost of dressings, but also due to a greater number of dressing changes in the silver dressings group. Although experts involved in the production of this evidence summary advised that it reflected standard practice at the time it was undertaken, this study (and its cost‑effectiveness analysis) has been criticised for its relevance and generalisation to everyday clinical care; for example, participants in the study did not necessarily have wounds that were infected or at high risk of becoming infected (Gottrup and Apelqvist 2010).

Jemec et al. (2014) used data from the meta‑analysis by Leaper et al. (2013) to evaluate the cost effectiveness of a specific brand of silver dressings (Biatain Ag) compared with non‑silver dressings for treating hard‑to‑heal venous leg ulcers in UK primary care for 4 weeks.

The study estimated that the initial 4 weeks of treatment in primary care was more expensive for the group treated with silver dressings (£623.52) compared with non‑silver dressings (£533.60). However, because of a shorter time to wound healing (13.8 weeks compared with 16.7 weeks) and less need for referral for specialist care, the average total treatment cost per person was lower for silver dressings (£1,326.57) compared with non‑silver dressings (£1,468.14) with a cost saving of £141.57 (95% CI £7.24 to £275.97). It is unclear how the outcome time to wound healing was obtained from the outcomes presented by Leaper et al. (2013) (primarily reduced ulcer area).

Conclusion: The limitations of the study by Leaper et al. (2013) subsequently limit the quality of the cost‑effectiveness analysis and affect its application to practice. Also, Jemec et al. (2014) only assessed use of silver dressings for 4 weeks and cost effectiveness of use for shorter and longer periods is not known. The study by Leaper et al. (2013) used Biatain Ag dressings and costs may differ for other silver dressings. Jemec et al. (2014) also assumed that all ulcers would heal, whereas in practice some ulcers may become re‑infected or worsen, and other complications may occur.

Cochrane review: Dressings and topical agents for arterial leg ulcers

This Cochrane review (Forster and Pagnamenta 2015) found no studies on wound dressings that met the inclusion criteria.

Conclusion: There is insufficient evidence to determine whether the choice of dressing (or topical agent) affects the healing of arterial leg ulcers.

Cochrane review: Topical silver for treating infected wounds

This Cochrane review (Vermeulen et al. 2007), which has already been considered in the venous leg ulcers section of this evidence summary, identified only 3 RCTs (n=847) with a short follow‑up of 4 weeks. Silver‑containing foam and alginate dressings did not statistically significantly increase complete ulcer healing compared with standard foam dressings or best local practice after up to 4 weeks of follow‑up, although a greater reduction in ulcer size was observed with the silver‑containing foam.

Conclusion: The authors of the Cochrane review noted that the 3 RCTs were small and of low power, and did not use measures of wound infection as outcomes. Therefore, they concluded that, although the methodology of the included RCTs was acceptable, there was insufficient evidence to recommend the use of silver dressings in the treatment of infected or contaminated wounds.

Meta‑analysis: Silver treatments and dressings for leg wounds and ulcers

This meta‑analysis (Carter et al. 2010) included 10 RCTs (n=1,356) that assessed silver treatments and silver dressings for healing leg wounds and ulcers. Meta‑analyses found no statistically significant difference between silver dressings and control dressings in complete wound healing (7 RCTs, n=1,118), although reduction in wound size was greater with silver dressings (5 RCTs, n=1,000; mean difference 10.29%, 95% CI 3.86% to 16.71%).

Although they noted that all of the RCTs on silver dressings had quality or bias issues, none were considered by the authors to be poor quality. However, this study assessed the quality of the evidence using an atypical approach that included reporting quality, external validity, bias, confounding and power, using differing methodologies. This means the quality of the meta‑analysis is questionable.

Conclusion: The authors concluded that the results provide some evidence that silver dressings improve wound healing, in terms of reduction in wound size, in the short term. However, there was no evidence that silver dressings are effective for complete wound healing and measures of infection were not assessed. Also, the included RCTs had limitations, including lack of blinding or allocation concealment, use of inappropriate analyses, incomplete reporting, lack of generalisability to real world populations, differences in baseline characteristics and loss of patients to follow‑up.

Cochrane review: Topical silver for preventing wound infection

This Cochrane review (Storm-Versloot et al. 2010) on topical silver products (dressings or creams) for preventing wound infection identified 26 RCTs (n=2,066), 20 of which considered burns. Six RCTs compared sulfadiazine cream with silver dressings, 2 in partial thickness burns (n=132) and 4 in full‑thickness or severe burns (n=267). One RCT (n=27) showed statistically significantly fewer infections with silver dressings compared with silver sulfadiazine, the remaining 5 found no evidence of a difference.

Six RCTs compared silver sulfadiazine or silver dressings with non‑silver dressings for acute, chronic or mixed wounds. Most comparisons found no statistically significant differences in infection rates, although 1 RCT (n=292) in a variety of wounds found statistically significantly fewer infections with silver sulfadiazine plus hydrocolloid dressings compared with paraffin‑impregnated gauze dressings. An RCT in acute wounds (n=209) found significantly more infections with silver sulfadiazine compared with neomycin sulphate. One RCT (n=434), which compared silver‑containing hydrofibre dressings with calcium alginate dressings in people with diabetic foot ulcers, found a statistically significant reduction in healing time with silver dressings.

Most of the trials were small and of poor quality, with many demonstrating a high or uncertain risk of bias.

Conclusion: Overall, the authors of the Cochrane review considered that there was insufficient evidence to support the use of silver‑containing dressings or creams because, generally, they did not promote wound healing or prevent wound infections.

Cochrane review: Honey as a topical treatment for wounds

This Cochrane review (Jull et al. 2015) compared honey applied topically by any means, alone or in combination with other dressings or components, compared with dressings or other topic agents. A diverse range of acute and chronic wounds was considered.

This Cochrane review found there is high‑quality evidence (2 RCTs, n=992) that honey dressings heal partial thickness burns more quickly than conventional dressings (polyurethane film dressings, paraffin gauze, sterile linen, framycetin‑impregnated tulle or left exposed). However, it is unclear if there is a difference in rates of adverse events (very low‑quality evidence) or infection (low‑quality evidence).

There is very low‑quality evidence (4 RCTs, n=332) that burns treated with honey heal more quickly than those treated with silver sulfadiazine. High‑quality evidence from 6 RCTs (n=462) found that there is no difference between these treatments in the overall risk of healing within 6 weeks, but an increased risk of adverse events with silver sulfadiazine.

There is low‑quality evidence (2 RCTs, different comparators, n=140) that honey heals a mixed population of acute and chronic wounds more quickly than silver sulfadiazine or sugar dressings. Honey healed infected post‑operative wounds more quickly than antiseptic washes followed by gauze and was associated with fewer adverse events (1 RCT, n=50: moderate‑quality evidence).

Very low‑quality evidence from another small RCT (n=40) suggests that honey may heal pressure ulcers more quickly than saline soaks. The effect of honey relative to comparators is unclear for venous leg ulcers (2 RCTs, n=476; low‑quality evidence), diabetic foot ulcers (2 RCTs, n=93; low‑quality evidence) and mixed chronic wounds (2 RCTs, n=150; low‑quality evidence).

The patient populations and comparators studied were heterogeneous and the evidence was affected by bias and imprecision, and was generally low quality.

Conclusion: The authors of the Cochrane review concluded that honey appeared to heal partial thickness burns and infected post‑operative wounds more quickly than comparators. However, the comparators used may not be relevant to current practice, reducing the relevance and generalisability of the results. Evidence for differences in the effects of honey and comparators when used for other wounds is of low or very low quality and does not form a robust basis for decision‑making.

Systematic review: Iodine in wound care

This systematic review (Vermeulen et al. 2010) included 27 RCTs (number of participants not reported) that reported on chronic and acute wounds, burn wounds, pressure sores and skin grafts. No meta‑analyses could be performed because of heterogeneity in wound care products, wound types and outcomes.

Most RCTs reportedly showed no substantial differences in beneficial or adverse effects between iodine (mainly povidone or cadexomer iodine) and comparators. Results did not differ between different types of wounds.

In RCTs that found a statistically significant difference, iodine was found to be superior to non‑antiseptic dressings (paraffin dressings, dextranomer and zinc paste) and other antiseptic agents (such as silver sulfadiazine or chlorhexidine dressings), but inferior to a local antibiotic (rifamycin) in reducing bacterial count and/or wound size. The number of RCTs and participants for comparisons are not clearly reported in the paper.

In 3 RCTs, no effect of iodine on thyroid function was seen. However, the authors noted that the design of the RCTs included in the systematic review may not have been appropriate to assess adverse events.

Trial quality was assessed using a Cochrane Collaboration checklist and additional criteria and, overall, was found to be limited. Many of the RCTs were over 10 years old at the time of the systematic review (2010) and not performed to present‑day standards. Comparators used may not reflect current practice.

Conclusion: The authors concluded that iodine does not appear to be inferior to other antiseptic agents and does not impair wound healing. However, there is a need for high‑quality RCTs addressing the effectiveness and safety of iodine to treat or prevent wound infection, in order to clearly determine its place in present‑day wound care.