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Developments in point-of- care wound diagnostics

Zena Moore
29 April, 2013  
Point-of-care diagnostics readily provide objective data pertaining to a wound and facilitate the selection of the correct treatment for the patient, when and where it is needed
Zena Moore PhD FFNMRCSI RGN
Deputy Head of the Department,
Lecturer in Wound Healing and Tissue Repair and Research Methodologies,
Royal College of Surgeons in Ireland, Ireland
Wounds and their associated problems have challenged healthcare providers and patients for centuries. Today, more than ever, in the presence of limited resources, yet spiralling demands, wound management services need to ensure that they are providing cost-effective, efficient care. Fundamental to this is the accurate assessment of the individual in order to make a correct diagnosis, thereby facilitating the choice of the correct treatment modality. Such an approach is closely aligned to patient safety, which is often threatened by sub-standard wound care treatment.
The problem of wounds
The management of individuals with wounds spans all healthcare settings, including primary care, secondary care and long-term care settings. Further, wounds are not unique to specific age groups and, as such, can be seen across the whole age spectrum. Despite the wealth of knowledge available, neither the incidence nor prevalence of wounds is reducing.(1) Indeed, the population prevalence of wounds is 3–4/1000 people, equivalent to between 1.5–2.0 million of the 491 million inhabitants of the EU 27, with an annual incidence of four million individuals.(2) 
Wounds and their associated problems have a profound effect on the individual, affecting all the domains of the activities of daily living. In addition, wounds are expensive, for example, with a prevalence of 1.0–1.4 million diabetic foot ulcers in the EU 27, the annual associated costs are estimated at €4–6 billion. Similarly, for venous leg ulcers, with a prevalence of 49,000–1.3 million in the EU 27, the annual associated costs are estimated at €6.5 billion.(2) 
From a healthcare delivery perspective, between 25% and 50% of acute hospital beds are occupied by patients with a wound, with up to 60% of these representing non-healing wounds (infected surgical wounds, pressure ulcers, leg/foot ulcers).(2) Indeed, it is argued that surgical site infections (SSIs) account for 17% of all nosocomial infections. 
Furthermore, European figures suggest that the mean length of extended hospital stay attributable to SSIs is 9.8 days, at an average cost per day of €325.(3) International pressure ulcer prevalence rates vary from 8.8% to 53.2% and incidence rates vary from 7–71.6%.(4) From a European perspective, pressure ulcer management absorbs between 4% and 5% of the annual health care budget, with nurse or healthcare assistant time accounting for up to 90% of the overall costs.(2)
 
Health economics is based on the concept of scarcity, which suggests that there will never be sufficient resources to meet the ever-changing health needs of society.(5)  Thus, the underlying premise is that the delivery of healthcare should be founded on equity and efficiency, in other words, making the best use of the resources that are available.(5) Of course this is difficult, particularly when one considers changing demographic profiles and the related challenges in providing adequate healthcare. 
The ability to manage increasing demands on the health service is greatly influenced by the available resources.(5) It is unlikely that there will ever be enough revenue to meet all healthcare challenges; therefore, prevention of unnecessary health-related complications is more important than ever.(6) Indeed, the EU commission warns that compromising on patient safety is costly, for example, between 13% and 16% of hospital costs are due to healthcare-related injuries and ill health.(6) Thus, the development of cost-effective patient safety programmes is central to ensuring sustainability in health care delivery into the future.
Planning wound interventions
Accurate and ongoing patient and wound assessment is essential in order to correctly identify the underlying aetiology of the wound and the potentially compounding patient factors that may delay healing.(7) Once this is established, the plan of care may be developed, implemented and subsequently evaluated. Although this may seem to be a relatively straightforward process, in reality it is not. For example, in one study, inter- and intra-rater reliability among nurses and doctors, of the red, yellow, black (RYB) classification of wounds, in addition to the assessment of exudate, was determined.
Agreement for the RYB among nurses was good (k=0.61) and this was similar for doctors (k=0.61). However, even with this level of agreement, there remain almost 40% of cases where nurses and doctors could not agree on the assessment of the condition of the wound bed. For the assessment of exudate there was only moderate agreement (k=0.49 for nurses; k=0.48 for doctors), meaning that in over half of cases, individuals were not assessing the level of exudate in a consistent manner.(8) 
In a further study, Stremitzer and colleagues(9) have shown that the assessment of wounds remains really challenging in clinical practice, with clinicians consistently demonstrating an inability to recognise and classify wound tissue types correctly (50% of doctors and 62% nurses). However, despite this inconsistency, it is this assessment that determines the choice of dressing. Furthermore, access to appropriate wound management services is intrinsically linked to the potential for good clinical outcomes. Yet, a study by McCluskey and McCarthy in 2012(7) noted that, of a sample of 150 nurses in the acute care setting, the majority felt that they were only moderately competent in wound assessment.
Furthermore, 25.5% of nurses chose decreasing the bacterial burden as the main objective in treating an otherwise healthy granulating wound. This suggests that there is often confusion in practice and, as such, patients may not always have their clinical needs met in an appropriate manner. At its essence, Stremitzer and colleagues(9) argue that objective measures are required to produce consistent wound assessment information, as this is the basis for planning future interventional strategies. 
From a clinical research perspective, the use of validated, objective, measures of wound healing outcomes are fundamental to the development of a sound evidence base for wound management. As a result of issues such as inadequate sample sizes, non-blinded outcome assessment, inadequate follow up and lack of clear descriptions of interventions, wound care research often falls short of expectations.(10)
Consequently, from a Cochrane Collaboration perspective, systematic reviews in wound care often conclude that there insufficient evidence to support or refute use of treatment modalities commonly used in practice; these comments arise largely due to the poor methodological quality of the studies reviewed, with use of subjective outcome measure impacting negatively on quality appraisal.(10)
 
Point-of-care diagnostics in wound management 
Many wounds are compromised by a local wound environment which is fundamentally detrimental to healing. Often this arises due to an imbalance between the stimulation and inhibition of proteases within the wound.(11)  As a result, a chronic inflammatory state often exists with high levels of proteases within the wound bed, which serve to damage the growth factors and cells required for wound repair.(11) Indeed, Yager and colleagues(11) demonstrated that, compared with surgical wounds, there was an imbalance between proteases and their inhibitors in pressure ulcer wound fluid. The concern is that, in the presence of elevated protease activity, there is a 90% chance that the wound will not heal.(12)  Conversely, not all non-healing wounds have excess levels of proteases; indeed, the study demonstrated that just 28% of wounds had elevated protease activity, suggesting that there must be other contributing factors which are delaying healing. 
Protease levels cannot be seen by the naked eye and thus cannot be readily quantified.(13) This in itself poses a major challenge for practising clinicians as it is the inability to clearly identify the processes going on within the wound which compounds the challenges in selecting the most appropriate treatment modality. Thus, it is clear that the process of wound assessment is difficult, and it is the undetected processes occurring in the wound that make the diagnosis and subsequent management planning challenging.(13)
 
The clinician faces a number of choices; however, the underlying aim is to choose the right treatment, at the right time, which is directed at the specific needs of the patient.13 The difficulty is that more often than not this planning is made on guess work, rather than on objective data. At its essence, this increases the risk of over use, or under use, of treatment strategies all of which compounds the financial and psychosocial burden of wounds.(12) 
Snyder and Cullen(13) suggest that a diagnostic tool should provide information that does not necessitate significant interpretation, yet provides useful information pertaining to the diagnosis or assessment of the patient. Point-of-care diagnostics in wound management, therefore, have the potential to illuminate the assessment process, such that the therapeutic interventions chosen may be targeted at the specific needs of the individual. A currently available point of care diagnostic provides a quick and simple method for assessing whether there are elevated levels of proteases within the wound bed.(12)
Used in combination with a full patient assessment, this tool has a number of potential benefits, for example, accurate diagnosis of elevated proteases facilitates the early use of protease modulation therapies, thereby enhancing the potential for positive clinical outcomes. In addition, the diagnostic has the potential to guide treatment strategies in a more objective manner, clearly providing guidance for when products should be stopped, continued or altered. From a health and social gain perspective, this has far-reaching implications, as there is an ever-increasing imbalance between available resources and rising health service demands. Anything that may contribute to enhanced diagnosis, targeted use of interventions and superior clinical outcomes is of significant interest to clinicians and patients alike. 
Conclusions
The provision of appropriate wound management services is closely aligned with patient safety initiatives; indeed, failure to provide adequate care compounds the suffering of the individual significantly, increasing the financial burden on health services. Assessment plays a fundamental role in providing relevant information needed for planning patient care. However, assessment is fraught with challenges, owing to the difficulty in objectively assessing certain parameters within the wound. Point-of-care diagnostics readily provide objective data pertaining to the wound and, in doing so, facilitate the selection of the correct treatment for the patient, when and where it is needed. At its essence, this is the basis for evidence-based practice, which is a central tenet of today’s healthcare delivery. 
References
  1. Moore Z, Cowman S. The need for EU standards in wound care: an Irish survey. Wounds UK 2005;1:20–8.
  2. Posnett J et al. The resource impact of wounds on health-care providers in Europe. J Wound Care 2009;18:154–61.
  3. Leaper DJ et al. Surgical site infection: a European perspective of incidence and economical burden. Int Wound J 2004;1:247–73.
  4. Scott JR et al. Incidence and characteristics of hospitalized patients with pressure ulcers: State of Washington, 1987 to 2000. Plastic Reconstruct Surg 2006;117:630–4.
  5. Phillips CJ. Introduction. In: Health Economics an Introduction for Health Professionals (Phillips CJ ed). BMJ, Oxford:1–17;2005
  6. European Commission. Patient safety: Commission publishes report on state of play in the Member States. In Midday Express. Press and Communication Service, Brussels;2012.
  7. McCluskey P , McCarthy G. Nurses’ knowledge and competence in wound management. Wounds UK 2012;8:37–47.
  8. Vermeulen H et al. Inter- and intra-observer (dis)agreement among nurses and doctors to classify colour and exudation of open surgical wounds according to the Red-Yellow-Black scheme. J Clin Nurs 2007;16:1270–7.
  9. Stremitzer S, Wild T, Hoelzenbein T (2007): How precise is the evaluation of chronic wounds by health care professionals? Int Wound J 2007;4:156–61.
  10. Clark M, Price P. Evidence -based practice: sound in theory, weaker in practice? ETRS Bulletin 2005;12:5–6.
  11. Yager DR et al. Wound fluids from human pressure ulcers contain elevated matrix metalloproteinase levels and activity compared to surgical wound fluids. J Invest Dermatol 1996;107:743–8.
  12. Cullen B et al. Protease activity levels associated with non healing chronic wounds. In: 22nd Conference of the European Wound Management Association, Vienna, Austria;2012.
  13. Snyder R, Cullen B. Point of care diagnostic tests in wound management Wound Care Hyperbaric Med 2011;2:59–67.