A randomized controlled trial of larval therapy for the debridement of leg ulcers: Results of a multicenter, randomized, controlled, open, observer blind, parallel group study Elizabeth Mudge, MSc1; Patricia Price, PhD2; Walkley Neal, PhD1; Keith G. Harding, MB, ChB1 1. Wound Healing Research Unit, Cardiff University School of Medicine, 2. Student Experience and Academic Standards, Cardiff University, Cardiff, United Kingdom

Reprint requests: Ms. E. Mudge, Wound Healing Research Unit, Cardiff University School of Medicine, Upper Ground Floor, Room 21, Heath Park, Cardiff CF14 4XN, United Kingdom. Tel: +44 029 20 74 41 00; Fax: +44 02920746334; Email: [email protected] This study is registered in a clinical trial database as follows—Eudra CT: 2007005775-34 Eudra CT (European Union Drug Regulating Authorities Clinical Trials) is the European clinical trials database of all clinical trials of investigational medicinal products. Manuscript received: February 25, 2013 Accepted in final form: September 9, 2013 DOI:10.1111/wrr.12127

ABSTRACT It has been known for centuries that the application of larvae is useful to heal certain wounds by facilitating debridement of necrotic tissue,1 yet the efficacy of larval therapy continues to be debatable. This study compared the clinical effectiveness of a larval therapy dressing (BioFOAM) with a standard debridement technique (Purilon gel; hydrogel) in terms of time to debridement of venous (VLU) or mixed arterial/ venous (MLU) leg ulcers. Data analyses were conducted on 88 subjects. Sixty-four subjects completed the full study. Of these, 31 of the 32 (96.9%) patients who completed treatment in the larvae arm debrided fully, compared with 11 of the 32 (34.4%) patients who completed the hydrogel arm. In addition, 42 (48%) ulcers fully debrided within the 21-day intervention phase, 31 (67.4%) from the larvae arm (n = 46), and 11 (26.2%) from the hydrogel arm (n = 42), which was statistically significant (p = 0.001) in support of larvae. A statistically significant difference was also observed between treatment arms with regard to numbers of dressing changes during the intervention phase of the study (p < 0.001) in that subjects in the larvae arm required significantly fewer dressing changes(mean = 2.83) than those in the hydrogel arm (mean = 5.40). There were no statistically significant differences in the clinical condition of the wound bed and surrounding skin by intervention. Subjects in the larvae arm experienced more ulcer-related pain or discomfort than subjects in the hydrogel arm (p < 0.001). This study provided good evidence to show that larval therapy, in the form of a BioFOAM dressing, debrided VLU and MLU considerably more quickly than a hydrogel, although the possibility of resloughing should be closely monitored.

It has been known for centuries that the application of larvae is useful to heal certain wounds by facilitating debridement of necrotic tissue,1 yet the efficacy of larval therapy continues to be debatable. It is estimated that 1.2–3.2 per 1,000 individuals in the United Kingdom have an active leg ulcer that requires treatment.2 The burden of care for chronic wounds to the National Health Service is great, with costs associated with the care of such patients running to £14.74–18.37 million.3 In addition to this financial cost, the cost to patients in terms of impact on daily living and quality of life cannot be underestimated.4 Chronic wounds often contain necrotic or sloughy tissue, which can harbor bacteria and act as a barrier to healing.5 Such an environment increases the risk of malodor and infection. Bacterial biofilms are increasingly recognized to play a critical role in the chronicity of wounds.6–8 Medicinal larvae have been shown to prevent the growth or the removal of bacterial biofilm from material used for surgical implants9,10 as well as from pig skin explants in vitro.11 This seems to be mediated by a nuclease secreted by larvae.12 Debridement, defined as the removal of sloughy, necrotic, or damaged tissue from a wound until the surrounding healthy tissue is exposed, Wound Rep Reg (2014) 22 43–51 © 2013 by the Wound Healing Society

is one of the cornerstones of good wound practice and is vital for reducing the bacterial burden within the wound13,14 and thus considered essential for optimizing wound healing.15 According to the definition of debridement,16 the removal of biofilm, alongside devitalized tissue and slough, can be considered part of the debriding activity of larvae. Several different debridement techniques are used in practice, yet research evidence on debridement is limited and systematic reviews have found no randomized controlled trial (RCT) that has shown that debridement speeds healing or that it reduces infection in chronic wounds. Furthermore, there is no RCT evidence to support any particular method of debridement, although there is some evidence to support the use of hydrogels.17,18 Hydrogels promote wound debridement by rehydration of nonviable tissue, thus facilitating the process of natural autolysis: amorphous hydrogels are the most commonly used and are thick, viscous gels.19 They are considered to be a standard form of management for sloughly or necrotic wounds. Arguably, surgical removal of slough and necrotic tissue is a more rapid means of debridement, but provision for this option is limited by the availability of appropriately trained personnel and the suitability of patients for anesthesia. 43

RCT of larval therapy for leg ulcer debridement

Clinical experience suggests that larval therapy can achieve debridement more swiftly than wound dressings. One RCT of larval therapy, involving only 12 patients with VLU20 found that larval therapy resulted in quicker debridement compared with a hydrogel. A Health Technology Assessment-funded trial (VenUS II) investigating larval therapy for VLU compared free-roaming larvae, larvae contained in bags (BioBags, Biomonde, Barsbüttel, Germany), and hydrogel showed that larval therapy significantly reduced the time to debridement compared with hydrogel. The therapeutic action underlying larval debridement therapy can be described as multifactorial with larvae exerting a beneficial effect on the healing of sloughy and infected wounds.21 The activity is primarily due to the mechanical and physiological properties of the larvae and is assisted by the enzymatic/chemical components of the therapy. Larvae thrive on proteinacious material, which they digest extracorporally and subsequently take up as their food. Proteolytic activities contained in larval secretions were described by Hobson et al. in 1931,22 Vistnes et al. in 1981,23 and Schmidtchen et al. in 2003.24 More recently, one key enzyme, insect-specific serine proteinase with a chymotrypsin-like activity, was isolated from secretions of Lucilia sericata larvae and shown to degrade venous leg ulcer slough ex vivo.25,26 The impact of L. sericata larvae on the wound healing process and granulation tissue formation has been shown, in particular by modifying fibroblast adhesion to collagen and fibronectin,27 and there is further evidence of synergism between larval excretions that have been shown to influence the antibacterial activity of different antibiotics.28,29 Although anecdotal clinical evidence suggests that larvae therapy is successful, there are limited data from RCTs to support the claim in clinical practice. In order to improve the efficiency of this treatment and cope with the exudate produced by wounds, a new approach to larval therapy was developed in which the larvae are contained within a bag made of fine mesh together with polyurethane foam cut into small pieces. It was postulated that this method of delivery may also increase ease of use and reassure patients that all the larvae are contained within the dressing. This new approach to larval therapy required evaluation within an RCT framework and was the intervention under investigation in this study.

AIM This study aims to compare the clinical effectiveness of a larval therapy dressing (BioFOAM, BioMonde Ltd, Bridgend, United Kingdom) with a standard debridement technique using a hydrogel (Purilon, Coloplast A/S, Peterborough, United Kingdom) in terms of time to debridement of venous (VLU) or mixed arterial/venous (MLU) leg ulcers, as part of standard practice. Sample

People with leg ulcers diagnosed as either of venous leg ulcer (VLU) or mixed etiology leg ulcer (MLU) quantified by an ankle brachial pressure index equal to or greater than 0.5 mmHg and which contained over 25% slough/necrotic material were identified and recruited via hospital wards (inpatients), outpatients, community leg ulcer clinics, and community nurse caseloads. 44

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The sample size calculation was based on data from a previous study.30 It was estimated that 60% of subjects would achieve debridement in the larvae group vs. 25% in the hydrogel group. Using this assumption, it was calculated that 31 subjects would be required in each group to complete the study. Allowing for 28% attrition rate, a total of 88 subjects were therefore recruited, based on alpha at 0.05 and to achieve 80% power. The proposed sample size of 31 for each group gave a power of 81.2%.This computation assumed that the difference in proportions was 0.35 (0.60 vs. 0.25). Treatment

The wound bed was cleaned with saline solution, and Sudocrem (Forest Laboratories UK Limited, Dartford, United Kingdom) was applied to the surrounding skin. A larval therapy dressing or hydrogel was then applied to the wound, a secondary dressing (Interpose: Frontier Therapeutics Ltd., Blackwood, United Kingdom) was applied on top. The dressings were kept in place by a simple retention bandage, e.g., Tubifast (Mölnlycke Health Care Ltd, Dunstable, United Kingdom) and followed with compression therapy. The bandaging systems used were Profore® and Profore Light (Smith & Nephew Healthcare, Hull, United Kingdom). Procedure

Following fully informed written consent, subjects were randomized to one of two groups: larval therapy or hydrogel together with appropriate compression. Randomization was stratified by size. A reference ulcer containing at least 25% slough and/or necrotic tissue, ≥ 2 cm2 in area and at least 5 cm from any other ulcer was identified. Subjects were reviewed every 3–4 days: until debridement was complete or up to a maximum of 21 days, whichever came soonest. At each visit, the wound bed and surrounding skin was assessed. Blinded assessors evaluated whether or not the wound was debrided, and photographs were also taken for later confirmatory analysis blinded to treatment arm. The endpoint (“debridement”) was defined as a “clean wound bed that no longer required a debriding agent.” A final evaluation visit was scheduled for 7–14 days after the subject’s last study visit. The final review allowed observation of the wound to ascertain whether resloughing had occurred. In routine clinical practice, a maintenance dose of larval therapy is advised once wound debridement is completed. This maintenance dose was not used in the study as the use of a comparator maintenance dose for a hydrogel was not deemed to be routine practice. Statistical methods

Demographic data were presented to ensure that the randomization resulted in equivalent groups at baseline. Data analysis was conducted on an “intention-to-treat” basis using the last value carried forward method with strict adherence to the protocol. The primary analysis compared the time to complete debridement of the reference ulcer between the randomized groups. A Kaplan–Meier survival curve was constructed for time to debridement for the two groups. Statistical significance levels were set at p = 0.05 (for the primary analysis Wound Rep Reg (2014) 22 43–51 © 2013 by the Wound Healing Society

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RCT of larval therapy for leg ulcer debridement

Time to Debridement 1.0

Proportion Debrided

0.8

Purilon

0.6

0.4 Randomization Arm BioFOAM

0.2

BioFOAM

Purilon BioFOAM-censored Purilon-censored

0.0 0

2 4 6 Total Number of Visits (Excluding Follow-up Visit)

n = 64), the percentage of ulcers in the larvae arm that fully debrided during the intervention was 96.9% (n = 31 out of 32) compared with only 34.4% (n = 11 out of 32) from the hydrogel arm. Debridement was further analyzed by ulcer size, ulcer duration, and ulcer etiology at baseline. A statistically significant difference was noted for wound size at baseline (p = 0.003); the majority of ulcers classified as large in size (>25–100 cm2) did not debride during the study intervention phase. No statistically significant differences were noted for duration of ulcer or etiology of ulcer at baseline in terms of wound debridement. Sixty-four subjects completed the full study (meeting the 80% power target). Twenty-six subjects were withdrawn (29.5%), 14 from the larvae arm and 10 from the hydrogel arm (see Figure 2). The most frequent reasons for withdrawal were “infection/increased slough” (hydrogel n = 9, larvae n = 3) and “pain/discomfort” (hydrogel n = 1, larvae n = 8). The other reasons for withdrawal in the larvae arm (n = 3) were due to the patient removing the dressing or requesting no further treatment.

Figure 1. Kaplan–Meier survival curve demonstrating time to debridement for both study arms. Log-rank (Mantel–Cox) test: X 2 = 36.414, df = 1, p < 0.001.

with alpha at 0.05). Secondary endpoints related to pain experience, the condition of the wound bed and surrounding skin, and cost data were analyzed on an exploratory basis. Ethics

All necessary permissions were obtained from Oxfordshire Independent Research Ethics Committee and local research and development departments. Participation was entirely voluntary, and patient care was not affected in any way by their decision to participate or not to participate. The study was conducted in full accordance with the world medical association Declaration of Helsinki Ethical Principles for Medical Research Involving Human Subjects (52nd WMA General Assembly, Edinburgh, Scotland, October 2000), the Good Clinical Practice Consolidated Guideline approved by ICH and SIs 1031 (2004), 1928 (2006) and any applicable national and local laws and regulations.

RESULTS Data analyses were conducted on 88 subjects, of these 46 (52%) were randomized to the larvae arm and 42 (48%) were randomized to the hydrogel arm. Allocation to the two treatment arms was relatively equal when analyzed by crosssectional wound area at baseline, and there was no statistical difference between the two groups. Forty-two (48%) ulcers fully debrided within the 21-day intervention phase, 31 (67.4%) from the larvae arm (n = 46), and 11 (26.2%) from the hydrogel arm (n = 42). The difference between the two study arms in terms of numbers of ulcers fully debrided during the intervention phase was statistically significant (p = 0.001) indicating greater incidence of debridement in the larvae arm (see Figure 1 and Table 1). Furthermore, when the percentage of ulcers that debrided were compared by excluding withdrawn patients (cohort Wound Rep Reg (2014) 22 43–51 © 2013 by the Wound Healing Society

Table 1. Incidence of debridement during study intervention (baseline to day 21) analyzed on the basis of intention to treat Ulcer completely debrided during intervention Yes No Total

Randomization arm Larvae

Hydrogel

Total

31 (67.4%) 15 (32.6%) 46 (100%)

11 (26.2%) 31 (73.8%) 42 (100%)

42 (47.7%) 46 (52.3%) 88 (100%)

X 2 = 14.938, df = 1, p < 0.001.

Figure 2. Flow of subjects through the study.

45

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Table 2. Baseline demographics by intervention by treatment arm

Gender Male Female Age range 31–40 years 41–50 years 51–60 years 61–70 years 71–80 years Above 81 years Treatment location Subject’s own home Community Acute setting Nursing home Research clinic Level of mobility Walks unaided Walks aided Wheelchair bound Totally immobile

Larvae (n = 46)

Hydrogel (n = 42)

Total (n = 88)

19 27

19 23

38 (43.2%) 50 (56.8%)

1 5 2 8 14 16

1 4 4 4 14 15

2 9 6 12 28 31

9 6 15 0 16

10 4 19 1 8

19 10 34 1 24

23 21 2 0

25 15 1 1

48 36 3 1

Demographic and other baseline characteristics

The distribution of baseline demographics between the groups was very similar by intervention. There was a higher proportion of female (56.8%) to male (43.2%) subjects, which would be expected in this cohort of patients. The majority of the subjects (67.0%) were aged 71 years and above. Treatment setting varied between the sites but was evenly matched between the treatment arms. The majority of subjects (95.5%) were able to walk (see Table 2).

Ulcer characteristics at baseline

Baseline ulcer characteristics were evenly matched between the treatment arms. The median duration of study ulcers at baseline was 7.5 months. The median duration of ulcers for the larvae arm (n = 46) was 7.0 months, and the median duration of ulcers for those in the hydrogel arm (n = 42) was 8.0 months; there was no statistically significant difference between the groups for this variable (p = 0.752). For 70.5% of the subjects, the ulcer under investigation was a new lesion. There was equivalent presentation of ulcers on the right and left limbs, with the majority being of venous etiology (87.5%). Shin (55.7%) and ankle (38.6%) were the most common location of ulceration and medial (42.0%) and lateral (36.4%) were the most common aspect. The majority of ulcers (80.7%) were described as shallow in depth that was defined as involving dermal tissue (see Table 3). 46

Appearance of wound bed at baseline

There were no significant differences in the clinical condition or appearance of the wound bed at baseline by intervention. The majority of ulcers were not odorous (88.6%), with 81.8% having slough covering more than half of the wound bed and 85.2% having granulation tissue covering less than half of the wound bed. A “moderate” amount of exudate was present on 67.1% of the ulcers and the periulcer skin was described as “erythema” in 48.9% of cases. Appearance of wound bed at final evaluation

There were no statistically significant differences in the clinical condition or appearance of the ulcers by intervention at the final evaluation. At the final evaluation visit, the wound bed, for the majority of ulcers, remained as not odorous (72.6%); however, the percentage that were odorous had increased from 11.4% at baseline to 27.4% at final evaluation. The percentage of ulcers having slough covering more than half of the wound bed had reduced from 81.8% at baseline to 41.2% at final evaluation. The number of ulcers with granulation tissue covering over half of the wound bed had increased from 14.8% at baseline to 41.2% at final evaluation. The amount of

Table 3. Baseline ulcer characteristics by intervention by treatment arm Larvae Hydrogel Total n = 46 n = 42 n = 88 (%) Ulcer history New ulcer Recurrent ulcer Ulcer etiology Venous Mixed Position of ulcer Left leg Right leg Location of ulcer Calf Ankle Shin Foot Aspect of ulcer Anterior Posterior Medial Lateral Depth of ulcer (data were missing for depth of ulcer for one subject) Superficial (not involving dermis) Shallow (involving dermis)

32 14

30 12

62 (70.5) 26 (29.5)

40 6

37 5

77 (87.5) 11 (12.5)

20 26

26 16

46 (52.3) 42 (47.7)

1 19 26 0

4 15 23 0

5 (5.7) 34 (38.6) 49 (55.7) 0

6 2 19 19

8 3 18 13

14 5 37 32

8

8

16 (18.2)

38

33

71 (80.7)

(15.9) (5.7) (42.0) (36.4)

Wound Rep Reg (2014) 22 43–51 © 2013 by the Wound Healing Society

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RCT of larval therapy for leg ulcer debridement

Table 4. Clinical description of ulcers by intervention at final evaluation

Wound malodor Yes No Slough/necrosis 25–50% > 50% Granulation 0–50% > 50% Exudate None Minimal Moderate Heavy Copious Condition of periulcer skin† Healthy Erythema Maceration Eczematous Other‡

Larvae Baseline n = 46

Larvae Final n = 43*

Hydrogel Baseline n = 42

Hydrogel Final n = 42

Total at baseline n = 88 (%)

Total Final n = 85 (%)

3 43

12 31

7 35

11 30

10 (11.4) 78 (88.6)

23 (27.4) 61 (72.6)

6 40

24 19

10 32

26 16

16 (18.2) 72 (81.8)

50 (58.8) 35 (41.2)

41 5

24 19

34 8

26 16

75 (85.2) 13 (14.8)

50 (58.8) 35 (41.2)

0 11 31 4 0

0 17 19 7 0

0 9 28 5 0

4 17 19 1 1

0 20 (22.7) 59 (67.1) 9 (10.2) 0

4 34 38 8 1

(4.7) (40.0) (44.7) (9.4) (1.2)

11 22 7 13 19

14 20 11 9 15

9 21 8 12 16

18 18 4 8 11

20 43 15 25 35

32 38 15 17 26

(37.6) (44.7) (17.6) (20.0) (30.6)

(22.7) (48.9) (17.0) (28.4) (39.8)

*Three subjects did not present these data for a final evaluation. † The number of “other” periulcer skin conditions exceeded the number of subjects as more than one condition could be offered. ‡ The descriptors for “other” periulcer skin conditions included atrophy blanche, dry and flaky, edema, hemosiderin, maceration, and scaring.

exudate noted at the final evaluation was generally lower than at baseline, the number of ulcers with no exudate had risen from 0% to 4.7%, and those ulcers with “minimal” exudate had increased from 22.7% at baseline to 40% at final evaluation. The most common descriptor for periulcer skin remained as “erythema,” although the percentage of wounds described with erythema was marginally lower at final evaluation (44.7%) than at baseline (48.9%) (see Table 4). Figures 3 & 4 show the progression of wound debridement during the study intervention.

Ulcer-related pain

Pain was measured using a self-administered visual analog scale (VAS) at each treatment visit. Subjects were requested to draw a line on the scale that best described the level of pain they had experienced during the previous week. The mean pain score for the whole cohort was 36.11 (range 0–100, SD 28.13), where a score of “0” represented “no pain” and a score of “100” represented “worst pain.” The mean baseline VAS pain score for subjects in the larvae arm (n = 46) was 41.54 (SD 28.80) and the mean baseline VAS score for subjects in the hydrogel arm (n = 42) was 30.17 (SD 26.44). The mean VAS pain scores at the final evaluation visit had decreased for Wound Rep Reg (2014) 22 43–51 © 2013 by the Wound Healing Society

all subjects in both study arms; for subjects in the larvae arm (n = 43), it was 19.26 (SD 21.48), and the mean VAS score for subjects in the hydrogel arm (n = 40) was 21.80 (SD 27.98). There was a statistically significant difference between overall mean VAS pain score at baseline compared with overall mean VAS pain score at the final assessment (p < 0.001, t-test = 4.826, df = 82) indicating that overall pain experience was lower at the final evaluation. Incidence of pain was further analyzed to establish whether ulcer duration at baseline had an influence on the severity of pain reported on the VAS scale. The mean pain score for subjects with ulcer duration ≤12 months was slightly higher at 37.44 (SD 29.66) indicating greater pain when compared with the mean pain score for subjects with ulcer duration >12 months, which was 33.41 (SD 25.00). No statistically significant difference in pain score was noted for duration of ulceration (t-test 0.629, df = 86, p = 0.531). Incidence of pain was further analyzed to establish whether ulcer etiology at baseline had an influence on the severity of pain reported on the VAS scale. The mean pain score for subjects with VLU was 35.77 (SD 28.37) indicating less pain in this group when compared with the mean pain score for subjects with MLU, which was 38.35 (SD 27.53). No statistically significant difference in pain score was noted for ulcer etiology (t-test −0.305, df = 86, p = 0.761). 47

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further assessed 7–14 days after completion of the study. Of the 31 ulcers in the larvae arm that debrided during the intervention, only nine (29%) had remained debrided at the follow-up visit, compared with seven (73%) of the ulcers in the hydrogel arm. The difference between the groups was statistically significant (p = 0.011) indicating that a greater number of ulcers in the larvae arm that had been classified as having fully debrided during the intervention had resloughed within a fortnight of the intervention. Patient adherence to and level of comfort of study intervention

Figure 3. Ulcer at baseline.

During the study, intervention phase (visit 2 to visit 7) participants were requested to complete Likert-type scale questions in which they were asked to describe the amount of time that they wore the study dressings, the level of comfort experienced in wearing the dressings and bandages, how comfort compared with previous treatments, and the subjects overall satisfaction compared with previous treatment. The majority of subjects stated that they wore the dressings and bandages for more than 3/4 of the time and rated the treatment as comfortable or very comfortable. However, a higher proportion of subjects in the larvae arm rated the treatment as uncomfortable or very uncomfortable. When asked to compare comfort of the study treatment with previous treatment, the majority of subjects rated comfort as “about the same”; however, more subjects in the larvae arm described the study treatment as “less comfortable,” and more subjects in the hydrogel arm described the study treatment as “more comfortable” than the previous treatment. The majority of subjects in both treatment arms described their overall satisfaction with the study treatment as “more satisfied.”

Dressing changes and number of treatment visits

Nurse rating of experience of study intervention

A statistically significant difference was observed between treatment arms with regard to numbers of dressing changes during the intervention phase of the study (p < 0.001) in that subjects in the larvae arm required significantly fewer dressing changes than those in the hydrogel arm. The mean number of dressing changes for subjects in the larvae arm was 2.83 (SD 1.102), whereas the mean number of dressing changes for subjects in the hydrogel arm was 5.40 (SD 1.795). The maximum number of dressing changes required for debridement in the larvae group was 4 (i.e., ulcer debrided by visit 5); the majority (n = 24) only required one (n = 15) or two (n = 9) larvae dressing applications. In the hydrogel group, three subjects’ ulcers were debrided at visit 3 and five subjects’ ulcers were debrided at visit 4; however, the majority of ulcers in this group (n = 19) had not debrided by the end of the study intervention phase and thus required in excess of seven dressing changes. The difference in number of treatment visits between the groups was also statistically significant (p < 0.001) in that those in the larvae arm required less treatment visits overall.

During the study intervention phase (visit 2 to visit 7), nurses were requested to complete Likert-type scale questions in which they were asked to rate the ease of application and ease of removal of the treatment. The majority of nurses rated the

Incidence of reappearance of slough

The incidence of reappearance of slough or necrotic tissue in those ulcers that had fully debrided (n = 42, [larvae arm n = 31, hydrogel arm n = 11]) during the intervention was 48

Figure 4. Ulcer 4 days post larvae application. Wound Rep Reg (2014) 22 43–51 © 2013 by the Wound Healing Society

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ease of application and the ease of removal of the study treatment as “very easy” or “easy.”

DISCUSSION Debridement of the wound bed is considered essential for optimizing wound healing, and although it is common practice, there remains little consensus with regard to methods and standards of debridement and to the specific role that debridement plays in the wound healing process. The principal finding of this study was that the use of larvae in the form of a dressing debrided VLU or MLU by removal of slough and necrotic tissue from the wound bed in a statistically significantly (p < 0.001) shorter period of time than a hydrogel. Furthermore, when withdrawn subjects were removed from the calculations, the percentage of ulcers that debrided in the larvae arm were 96.9% compared with only 34.4% from the hydrogel arm. These results imply that if pain relief, patient education and treatment concordance are appropriately managed the potential for larvae therapy to be effective and efficient at debridement of sloughy/necrotic tissue would be enhanced. The process of confirmation of debridement was robust; debridement of the wound bed was verified by a blinded assessor at the treatment visit and confirmed by two independent blinded assessors who substantiated that debridement had occurred by observation of photographs of the study ulcers. Wound debridement was further analyzed by ulcer duration, ulcer size, and ulcer etiology at baseline; neither ulcer duration (> 12 months, ≤ 12 months) nor etiology (VLU and MLU) showed statistically significant differences in rate of debridement; however, a significantly higher number of “large” ulcers (>25–100 cm2) did not debride during the study intervention (p = 0.003). The incidence of reappearance of slough or necrotic tissue was verified at a final evaluation visit conducted 7–14 days after completion of the study intervention. Less than half of the ulcers had remained debrided at this follow-up evaluation visit, and the difference between the groups was statistically significant (p = 0.011) indicating that a greater number of ulcers in the larvae arm had resloughed within a fortnight. In routine clinical practice, a maintenance dose of larvae dressing is recommended after debridement has been confirmed; however, this was not possible for use in this study as there was not a comparable maintenance dressing for the hydrogel. Randomization into the study was stratified by wound size (small 2–10 cm2, medium >10–25 cm2, and large >25– 100 cm2), and the two treatment arms were balanced at baseline to confirm consistency between these groups. The study population overall was comparable from a demographic point of view, and demographic data corresponded with previously reported studies using leg ulcer patients in the UK.31,32 Baseline ulcer characteristics were also evenly matched between both treatment arms. Arterial etiology leg ulceration was excluded from the study as bleeding can occur when using larval therapy and compression therapy would also be precluded in this group of patients. Previous research of larvae therapy had indicated that pain should be anticipated.30 Subjects’ pain experience was therefore assessed at each treatment visit. Those in the larvae arm experienced ulcer-related pain or discomfort more frequently Wound Rep Reg (2014) 22 43–51 © 2013 by the Wound Healing Society

RCT of larval therapy for leg ulcer debridement

than subjects in the hydrogel arm. More subjects were withdrawn from the study as a result of pain than for any other criteria. Incidences of pain were further analyzed by ulcer duration and ulcer etiology but neither showed statistically significant differences for pain experience.VAS pain scores were not comparable over time due to the fact that subject numbers in the larvae arm were markedly reduced beyond the second treatment visit, but at visit 2, there was a statistically significant difference in pain experience between the treatment arms (p < 0.001), indicating that pain experience was worse for those in the larvae arm. A statistically significant difference was observed between treatment arms with regard to numbers of dressing changes during the intervention phase of the study (p < 0.001) in that subjects in the larvae arm required significantly fewer dressing changes than those in the hydrogel arm, which would imply that treatment with larvae dressings might be more cost effective in terms of healthcare resources in the long term; however, specific cost utility evaluations were not conducted. A true cost evaluation would also need to include comparative data using other debridement techniques. Incidence of infection of the study ulcer during the study intervention were higher in the hydrogel arm (28.6%) compared with the larvae arm (6.5%); however, bacterial load was not investigated in this study, and criteria for infection were not confirmed. The appearances of the wound bed at the final evaluation visit showed no statistically significant differences in the clinical condition by intervention. The majority of ulcers remained as not odorous (72.6%), although the number of ulcers reported to have an odor had increased from 11.4% at baseline to 27.4% at final evaluation. As anticipated, slough and exudates in the wound bed were reduced at final evaluation, and granulation tissue had increased. Subject reports indicated that there was good adherence with the study treatment overall with the majority stating that that they wore the dressings and bandages for more than 3/4 of the time. The level of comfort of the dressings and bandages was varied but the majority of subjects rated the treatment as comfortable and rated the level of comfort as about the same as their previous treatment. The majority of subjects described satisfaction with the study treatment. Positive evaluations of the treatment were also provided by the majority of nurses who rated the ease of application and removal of the treatment as “very easy” or “easy.” This study provided good evidence to show that larval therapy debrided venous and mixed etiology leg ulcers considerably more quickly than a hydrogel, although the possibility of resloughing should be closely monitored. The results also showed a lower incidence of wound infection when using larval therapy. There is evidence from this study to show that larval therapy in a containable dressing used on sloughy or necrotic wound tissue is an efficient method of wound debridement and is capable of debriding a wound in a significantly shorter period of time than a hydrogel. However, a maintenance dose postulcer debridement should be recommended to limit resloughing. The considerable number of ulcers in the “large” category that did not debride poses the question of whether ulcer size might have an influence on choice of method of debridement; this requires some consideration and therefore warrants further investigation. 49

RCT of larval therapy for leg ulcer debridement

A number of other debridement techniques (such as sharp, surgical, enzymatic, and autolytic) are routinely used in wound care; further research is therefore required to explore the relationship between different methods of debridement, the relationship between debridement and healing, the impact of different wound types, and the effect of debridement on wound microbiology. Recruitment of sufficient numbers of eligible patients was a huge challenge for this study, and the original sample size was not met despite an extension in time and initiation of additional centers. The main reason for this was the nurse-led treatment setting in which the majority of patients with venous or mixed leg ulcers are currently managed; this impacted upon the ability of the study sites to recruit patients in accordance with International Conference on Harmonization of Good Clinical Practice guidelines that stipulate the need for a medic in attendance. Furthermore, recent hospital policy in UK dictates that all inpatients are given anticoagulation therapy while in hospital, which further impeded recruitment of this group of patients as anticoagulant therapy was an exclusion criterion for this study. Another limitation was that fewer ulcers than originally anticipated were covered in greater than 25% slough or necrotic tissue. The withdrawal rate was also higher than originally anticipated, which was surprising considering the short intervention phase of only 21 days and questions the ability for compliance to either treatment modality. No systematic evaluation of side effects or complications were conducted during the intervention, and it should also be noted that although a large number of secondary analyses were conducted, caution must be attached to the significance of any differences found as the study was only powered for the primary end point, and therefore other apparent differences must be regarded as simply suggestive.

ACKNOWLEDGMENTS Source of Funding: This research was funded by BioMonde Ltd (formerly ZooBiotic Ltd), Units 2–4, Dunraven Business Park, Coychurch Road, Bridgend, South Wales, CF31 3BG, UK. Conflict of Interest: None of the authors has an actual or potential conflict of interest. REFERENCES 1. Guthrie HC, Clasper JC. Historical origins and current concepts of wound debridement. J R Army Med Corps 2011; 157: 130–2. 2. Posnett J, Franks PJ. The costs of skin breakdown and ulceration in the UK. In: Pownall M, editor. Skin breakdown: the silent epidemic. Hull, UK: Smith & Nephew Healthcare Ltd., 2007. 3. Drew P, Posnett J, Rusling L. The cost of wound care for a local population in England. Int Wound J 2007; 4: 129–55. 4. Persoon A, Heinen MM, van der Vleuten CJ, de Rooij MJ, van de Kerkhof PC, van Achterberg T. Leg ulcers: a review of their impact on daily life. J Clin Nurs 2004; 13: 341–54. 5. White R, Cutting K. Critical colonisation of chronic wounds: microbial mechanisms. Wounds UK 2008; 4: 70–8. 6. Davies SC, Ricotti C, Cazzaniga A, Welsh E, Eaglstein WH, Mertz PM. Microscopic and physiologic evidence for biofilmassociated wound colonization in vivo. Wound Repair Regen 2007; 16: 23–9.

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A randomized controlled trial of larval therapy for the debridement of leg ulcers: results of a multicenter, randomized, controlled, open, observer blind, parallel group study.

It has been known for centuries that the application of larvae is useful to heal certain wounds by facilitating debridement of necrotic tissue,(1) yet...
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