Advice
The technology
The technology
The Woundchek Protease Status test (Woundchek Laboratories) is an in-vitro diagnostic test for the qualitative assessment of human neutrophil-derived inflammatory protease activity in chronic wounds, including matrix metalloproteases (MMPs) and human neutrophil-derived elastase.
This information is intended to guide treatment, for example using protease modulating therapies or dressings. In the same way, the test is also intended to identify wounds for which more advanced treatments (such as protease modulating therapy) are not necessary. A review by Lazaro et al. (2016) found that chronic wounds have higher levels of protease activity than acute wounds, and that there is a correlation between high MMP levels and delayed wound healing in chronic wounds.
The main components of the Woundchek Protease Status test are a test card and reagent. Reagent is added to the test card and then a fluid swab collected from the chronic wound is inserted into a slot in the test card, rotated and left for 10 minutes. After this incubation period, the test card is folded over and closed. Test results must be viewed exactly 5 minutes after this.
The results are shown by the intensity of the coloured test line (labelled T) on the card compared to a separate printed reference strip provided in the kit. The test is only valid if a second line, a control (labelled C on the card) becomes visible during the test. If proteases are present in the collected wound fluid, they degrade the synthetic peptide in the test card. High levels of protease activity are indicated when the colour of the test line is less intense than the line on the reference strip, or the test line is not visible at all. Low levels of protease activity are indicated when the intensity of the test line is more than or equal to the reference strip line.
A control kit can be used as a further reference for testing. This kit contains 3 low and 3 high protease activity control swabs that can be used to establish that the test is reporting the expected results. The manufacturer recommends using the kit once with each shipment of Woundchek tests, or in accordance with local laboratory protocols.
The innovation
The Woundchek Protease Status test is the only point-of-care in-vitro diagnostic test for the detection of elevated protease activity (EPA) in chronic wounds currently available.
Current NHS pathway
NICE has published guidelines on the prevention and management of foot problems in people with diabetes, pressure ulcers, and surgical site infections. Although these guidelines give important recommendations about wound care, they do not make recommendations on specific products. NICE advice on wound care products and advanced and antimicrobial dressings for chronic wounds states that dressing selection should be made after careful clinical assessment of the person's wound, their clinical condition, and their personal experience and preferences. The NICE advice also states that the least costly dressings that meet the required clinical performance characteristics should be used, as there is insufficient evidence to determine whether modern or advanced dressings (such as hydrocolloids, alginates and hydrofibre dressings) are more clinically effective than conventional dressings for treating wounds. Additionally, NICE advice states that there is currently no robust evidence supporting the use of antimicrobial dressings (such as silver, iodine or honey) over non-medicated dressings for treating chronic wounds. The Scottish Intercollegiate Guideline Network (SIGN) guideline on the management of venous leg ulcers recommends simple non-adherent dressings and compression therapy.
If the Woundchek Protease Status test was widely adopted in the NHS, it would be used in addition to current wound care practices. If EPA is detected, protease modulating therapies or dressings may be chosen to treat wounds instead of more basic dressings. Where EPA is not detected, the more basic, cheaper dressings may be used instead. Also, assessments of infection and microbial colonisation can be done, to determine whether an anti-microbial dressing may be of more benefit to the patient.
Population, setting and intended user
Chronic wounds are often treated by wound care nurses in hospital or attending people in their homes. The Woundchek Protease Status test can be used in any setting, including in a patient's home, by clinical staff with the appropriate experience and training.
Costs
Device costs
Prices (excluding VAT) for Woundchek Protease Status tests, control kits and reagent accessory packs are presented in table 1. There are no other costs associated with maintenance or calibration because neither are needed. Initial product training is offered by the company at no extra cost.
Table 1: Woundchek Protease Status test costs
|
Description |
Cost |
Additional information |
|
Woundchek Protease Status test |
£30 |
Per single-use test |
|
Control test kit |
£15 |
Contains 3 low and 3 high protease activity result control swabs for visual reference of possible test results |
|
Reagent accessory pack |
£18 |
Contains 3 reagent bottles |
The Woundchek Protease Status test and reagent accessory packs have a shelf-life of 21 months from the date of manufacture, and the control kits have a shelf-life of 12 months.
Resource consequences
The Woundchek Protease Status test is not currently used routinely in any NHS trusts but evaluation studies are planned in 3 centres.
The test would present an additional cost to standard care.
Testing for EPA may be used in the clinical decision about which wound dressings to use. Protease-modulating dressings are generally more expensive than standard dressings. If a negative EPA test was used to change treatment to a cheaper, standard dressing then this may lead to some cost savings. It is not clear whether this would happen in practice because protease modulating dressings are often used without previous testing for EPA. Protease modulating dressings may also be used in patients without EPA, as they are often highly absorbent. The costs of some protease modulating dressings and other dressings are shown in table 2.
Table 2: Costs of protease modulating dressings and other dressings
|
Description |
Cost (NHS Supply Chain) |
Additional information |
|
Protease modulating dressings |
||
|
Promogran |
£5.80 |
28 cm2 |
|
Promogran Prisma |
£7.07 |
28 cm2 |
|
UrgoStart Contact |
£2.94 to £9.88 |
5 x 7 cm to 15 x 20 cm |
|
UrgoStart |
£4.69 to £11.70 |
6 x 6 cm to 15 x 20 cm |
|
UrgoStart Border |
£5.43 to £15.54 |
8 x 8 cm to 20 x 20 cm (sacrum) |
|
Other dressings |
||
|
UrgoTul contact |
£3.20 |
10 x 10 cm |
|
Aquacell foam dressing |
£2.65 |
10 x 10 cm |
|
UrgoTul Absorb |
£2.78 |
10 x 10 cm |
|
Kendall non-adhesive foam dressing |
£1.00 |
10 x 10 cm |
|
Tegaderm hydrocolloid dressing |
£2.33 |
10 x 10 cm |
|
Hydrosorb hydrogel dressing |
£1.51 |
10 x 10 cm |
A study by Frenthoff et al. (2015) presented as a poster reported that identifying EPA in wounds using the Woundchek Protease Status test could save €2,044 (£1,748.95) on materials per wound identified because of a reduction in materials needed to treat the wound. Nherera et al. (2013) estimated a potential saving of £1,906 per wound identified as having EPA with the Woundchek Protease Status. However, this UK-based study, also presented as a poster, reported the cost of each Woundchek Protease Status test to be £21.50 compared with the current £30 list price.