Wool-derived Keratin Dressings for Venous Leg Ulcers

A pragmatic, community based, single-blind, usual care-controlled, randomised trial to determine whether keratin dressings increase the proportion of patients with venous leg ulcers healed at 24 weeks when used in addition to compression in patients with slow healing venous leg ulcers. Participants in have compression therapy (system of choice guided by patient and/or clinical preference) as delivered through district nursing services at the study centres as a background treatment. Keratin dressings will be applied when the compression bandage is changed (approximately weekly). Usual care dressings will consist of the usual formulary of moist wound dressings available at each study centre.

Participants will be district nursing service patients in five study centres in New Zealand with prevalent or incident venous leg ulcers. A venous leg ulcer will be defined as a wound on the lower leg that has remained unhealed for 4 or more weeks, appears to be primarily venous in aetiology with other causative diseases ruled out. If the participant has two or more venous leg ulcers, the largest ulcer will be the reference ulcer. A participant will be considered to have a slow healing venous leg ulcer if the ulcer area is larger than 5 cm2 and/or the ulcer has been present for more than six months.

Participants will receive up to four visits from the research nurse - visit 1 to screen for eligibility, visit 2 to consent and randomise the participant, visits 3 and 4 to collect outcome data. District nurses will continue to visit the participant (about weekly or more frequently if required) to provide routine care between research nurse visits.

Block randomisation will be used, stratified by study centre and prognostic index (ulcer size greater than 5cm2 and/or ulcer duration greater than 6 months) to ensure a balance of participants within study centres and for participants likely to be slow healers. Research nurses will input information on inclusion criteria, exclusion criteria, and relevant clinical history on consented participants via a tablet computer. The allocation will be generated after this information has been entered. Randomised participants will receive the allocated treatment until the reference ulcer heals or data collection is completed, whichever occurs sooner.

Inclusion criteria

• Clinical indications of venous leg ulceration
• Ankle Brachial Index ≥ 0.7
• Able to tolerate compression therapy
• Ulcer area > 5cm2 and/or ulcer duration > 6 months
• Able to provide informed consent.

Exclusion criteria

• Hypersensitivity to wool or wool alcohols
• Venous leg ulceration with exposed tendon or bone
• Infected venous leg ulcer at trial inception (eligible after infection resolved)
• Venous leg ulcer with critical bioburden at trial inception (eligible if resolved)
• History of rheumatoid arthritis or vasculitis
• Uncontrolled diabetes
• Severe liver, heart, or renal failure
• Severe peripheral arterial disease
• Suspected or diagnosed skin malignancy
• Other threat to safe participation.