This article for nurses on foot care for people with diabetes is the second in a series of five evidence reviews being written by Sarah Chapman for the British Journal of Community Nursing through 2017. It was published there in April.
The prevalence of diabetes, one of the most common chronic conditions in the UK, is increasing. In England, the number of people diagnosed with diabetes rose from 1.9 million in 2006 to 2.9 million in 2013 and this is expected to rise to more than 5 million by 2025. The life expectancy of people with diabetes is shortened by up to 15 years, and 75% die of macrovascular complications (NICE, 2016).
Diabetic neuropathy and peripheral arterial disease put people with diabetes at greater risk of foot problems and it is estimated that one in ten will have a foot ulcer due to diabetes during their lives. Diabetes is also the most common cause of limb amputation not associated with trauma, and 80% of these amputations will be preceded by foot ulceration (NICE, 2016).
Foot ulcers have a significant impact on people’s quality of life, while the annual cost to the NHS of foot ulcers or amputations was estimated to be around £650 million in 2012, or £1 in every £150. There is considerable regional variation in services and practice for preventing and treating foot problems in people with diabetes, highlighted by NICE in their latest guideline on Diabetic foot problems: prevention and management (NICE, 2016).
Evidence-based practice in foot care for people with diabetes
Evidence-based practice is the use of current best evidence in making decisions about the care of individual patients combined with clinical expertise and the patient’s preferences and values (Sackett DL et al, 1996). This evidence review will focus on Cochrane reviews relevant to diabetes-related foot ulcer, some of which have informed international guidelines, with some additional information from the International Best Practice Guidelines (Wounds International, 2013) and the International Working Group on the Diabetic Foot (IWGDF) Guidance 2015. In a series of reports on different aspects of foot care in people with diabetes (Bus et al, 2016a; Bus et al, 2016b; Game et al, 2016; Hinchliffe et al, 2016; Lipsky et al, 2016), and a ‘Summary Guidance for Daily Practice’ (Schaper et al, 2016), the IWGDF brings together evidence-based international consensus guidance and advice based on expert opinion where evidence is lacking. It is clear from the Cochrane reviews and from the wider body of evidence cited by the IWGDF that the evidence base is sub-optimal.
Approaches to prevention
Five key elements for the prevention of foot problems in people with diabetes have been identified by the IWGDF (Schaper et al, 2016):
- Identification of the at-risk foot
- Regular inspection and examination of the at-risk foot
- Education of patient, family and healthcare providers
- Routine wearing of appropriate footwear
- Treatment of pre-ulcerative signs
The at-risk patient is defined as ‘a patient with diabetes who does not have an active foot ulcer, but who has peripheral neuropathy, with or without the presence of foot deformity or peripheral artery disease, or a history of foot ulcer(s) or amputation of (a part of) the foot or leg’. The IWGDF states that all people with diabetes should have their feet examined at least once a year, and those with a risk factor more often, based on their risk category, whilst acknowledging that robust data are lacking on whom, how and when to screen (Bus et al, 2016b).
The IWGDF guidance also highlights that most of the studies on which it draws are single intervention studies, yet preventive foot care for this population generally consists of an integrated approach (Bus et al, 2016b). Patient education alone for reducing foot ulcer and amputation incidence has been evaluated in a Cochrane review (Dorresteijn et al, 2014), but the review authors found only small, flawed trials and were unable to draw firm conclusions about intervention effectiveness. In practice, education of patients, family and healthcare professionals, which aims to improve knowledge, skills (such as how to cut nails appropriately) and motivation to begin and sustain the work of foot care, is part of an integrated approach to care (Schaper et al, 2016).
A Cochrane review (Hoogeveen et al, 2015) aimed to assess the effectiveness of complex interventions in preventing foot ulcers in people with diabetes. Complex interventions were defined as “an integrated combination of patient level interventions, healthcare provider level interventions and/or structural interventions”. Patient level interventions aim to improve people’s health directly. For preventing and treating diabetes-related foot ulcers these could include podiatry care, assessment of ulcer risk and strategies to encourage good self-care such as motivational coaching. Interventions at the level of healthcare provider may aim to improve assessment and referral, while structural changes could be the introduction of a multidisciplinary team approach or a new system for encouraging regular follow-up.
The review includes six randomised studies evaluating a variety of complex interventions. Variations between studies precluded meta-analysis and all were at a high or unclear risk of bias, largely due to lack of information given. The authors conclude that there is a lack of evidence for the effectiveness of complex interventions for preventing or reducing foot ulcers in people with diabetes, and offer a reminder that this is not to be confused with evidence that they are not effective. Indeed, they suggest that the challenges of reducing foot ulcer incidence in people with diabetes are likely to need to be met with a combination of interventions, and call for high quality primary research to further develop the evidence base. The IWGDF guidance echoes this and highlights the need also for research to better understand who is likely to benefit from preventative interventions and which interventions should be included, as well as more work on what is effective for improving adherence to preventative foot care in people with diabetes (Bus et al, 2016b).
Treating diabetes-related foot ulcers
International Best Practice Guidelines (Wounds International, 2013) which, like the IWGDF, draw on clinical expertise where good evidence is lacking, has a helpful section on assessing foot ulcers in people with diabetes, and stresses that the key skill for the non-specialist practitioner is knowing when and how to refer a patient to the multi-disciplinary footcare team (MDFT). They say that evidence consistently highlights the benefits of MDFTs in improving outcomes for people with diabetes-related foot ulcers, but that there is considerable regional variation in provision across the UK. The IWGDF advocates the use of a standardized and consistent strategy for evaluating a foot wound, which includes an assessment of type, cause, site and depth, and site of infection (Schaper et al, 2016).
Foot ulcer treatment is underpinned by seven key elements:
- Relief of pressure and protection of the ulcer
- Restoration of skin perfusion
- Treatment of infection
- Metabolic control and treatment of co-morbidity
- Local wound care
- Education for patient and relatives
- Prevention of recurrence
As with preventive measures, a multi-disciplinary and holistic approach is recognised as good practice. IWGDF guidance notes that, with the exception of offloading, “the field remains blighted by the poor level of evidence to justify the use of any particular therapy in the management of ulcers.” Alarmingly, the authors also say that the number of high quality studies does not appear to be increasing (Game et al, 2016).
Relief of pressure
Even the evidence-base for offloading interventions, to redistribute pressures evenly in at-risk feet and to relieve pressure where an ulcer exists, has gaps, which are presented in the IWGDF guidance on footwear and offloading interventions along with their recommendations (Bus et al, 2016a). The preferred treatment for a neuropathic plantar ulcer is a non-removable knee-high offloading device, either a total contact cast or removable walker rendered immovable, which have been shown to be equally effective. A Cochrane review (Lewis and Lipp, 2013) found that non-removable casts may be more effective in healing diabetes-related plantar foot ulcers than removable casts or dressings alone. Weaknesses in the primary research, including poor reporting and small numbers of participants, allow only cautious conclusions, and the review was unable to shed any light on how treatment may affect the quality of life of those undergoing it.
There is another evidence gap here, in relation to how best to optimize glycaemic control. A Cochrane review (Fernando et al, 2016) comparing intensive with conventional glycaemic control for treating foot ulcers in people with diabetes found just one relevant trial and this had no results. Two ongoing trials were also identified, which may provide data for future updates of the review, but their completion date is unknown.
There is an enormous literature relating to the assessment and treatment of foot infections in people with diabetes. A Cochrane review on systemic antibiotics for this purpose concluded that it remains unclear “if any one systemic antibiotic treatment is better than others in resolving infection or in terms of safety” (Selva Olid et al, 2015). The IWGDF summary gives a useful overview of assessing and treating infection and identifies some key areas of uncertainty, including how best to monitor treatment and determine when infection has resolved; what imaging studies should be ordered; and the optimal duration of antimicrobial treatment for osteomyelitis (Lipsky et al, 2016).
Debriding the wound
Debridement, the removal of surface debris, slough and necrotic tissue, is advocated, but robust evidence to guide the use of this practice in general and any particular method of debridement is lacking (Game et al, 2016). The use of hydrogels for debridement has some evidence to support it, but this remains uncertain due to high risk of bias in the primary research, as found in the Cochrane review on this (Dumville et al, 2013a) and other systematic review evidence also cited by the IGWDF (Game et al, 2016). The International Best Practice Guidelines (Wounds International, 2013) acknowledge the evidence gap and say that, in practice, regular, local, sharp debridement using a scalpel, scissors and/or forceps is the gold standard, and should be carried out by practitioners with specialist training.
This is the aspect of treating foot ulcers in people with diabetes on which Cochrane has multiple reviews and an overview of systematic reviews (Wu et al, 2015), which combines six Cochrane reviews with seven non-Cochrane reviews. The included reviews were all assessed using AMSTAR as being moderate to high quality. Unfortunately, the primary research is not high quality, the reviewers identifying problems with design, conduct and reporting. They conclude that “there is currently no robust evidence of differences between wound dressings for any outcome in people with diabetes (treated in any setting).
The IWGDF acknowledges the poor evidence base. The guidance highlights the lack of robust evidence of effectiveness of honey-based dressings, citing Cochrane evidence (Jull et al, 2015), along with three other systematic reviews, and notes that other topical antimicrobials, such as silver-based or iodine-based products, are commonly in use but that their effectiveness, and how they compare, has not been reliably demonstrated.
The IWGDF suggests that dressing choice should be chosen based on exudate control, comfort and cost and the use of antimicrobial dressings with the aim of improving wound healing or preventing secondary infection avoided (Game et al, 2016).
Does topical negative pressure wound therapy promote ulcer healing?
Negative pressure wound therapy (NPWT) involves the application of continuous or intermittent negative pressure to a wound through a material that fills the wound, and wound exudate is extracted. A Cochrane review (Dumville et al, 2013b) found that, compared with moist dressings, NPWT may be more effective for healing post-operative foot wounds and ulcers in people with diabetes, but these findings are uncertain because of the low quality of the evidence. The IWGDF has also found that there is insufficient evidence to make a recommendation, but suggests it may be considered for post-operative wounds (Game et al, 2016; Schaper et al, 2016).
A multidisciplinary and holistic approach
Both the IWGDF and Wounds International stress the importance of a well-organized, multi-disciplinary team, using a holistic approach, in preventing and treating foot ulcers in people with diabetes (Schaper et al, 2016; Wounds International, 2013). Cochrane and non-Cochrane reviews have revealed serious limitations in the available evidence, which need to be addressed in future research for practice to become truly evidence-based. Until that happens, practice is largely missing a vital strand, where reliable evidence informs decisions, along with clinical expertise and the patient’s preferences and values.
References may be found here.
Sarah Chapman has nothing to disclose.