Foot care for people with diabetes: prevention of complications and treatment

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 prevalenceThe proportion of a population who have a particular condition or characteristic. For example, the percentage of people in a city with a particular disease, or who smoke. of diabetes, one of the most common chronicA health condition marked by long duration, by frequent recurrence over a long time, and often by slowly progressing seriousness. For example, rheumatoid arthritis. 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 riskA way of expressing the chance of an event taking place, expressed as the number of events divided by the total number of observations or people. It can be stated as ‘the chance of falling were one in four’ (1/4 = 25%). This measure is good no matter the incidence of events i.e. common or infrequent. 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 reviewsCochrane Reviews are systematic reviews. In systematic reviews we search for and summarize studies that answer a specific research question (e.g. is paracetamol effective and safe for treating back pain?). The studies are identified, assessed, and summarized by using a systematic and predefined approach. They inform recommendations for healthcare and research. 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):

1. Identification of the at-risk foot
2. Regular inspection and examination of the at-risk foot
3. Education of patient, family and healthcare providers
4. Routine wearing of appropriate footwear
5. TreatmentSomething done with the aim of improving health or relieving suffering. For example, medicines, surgery, psychological and physical therapies, diet and exercise changes. 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 factorAn aspect of a person's condition, lifestyle or environment that affects the chance of them getting a disease. For example, cigarette smoking is a risk factor for lung cancer. more often, based on their risk category, whilst acknowledging that robust dataData is the information collected through research. 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 interventionA treatment, procedure or programme of health care that has the potential to change the course of events of a healthcare condition. Examples include  a drug, surgery, exercise or counselling.   studies, yet preventive foot care for this populationThe group of people being studied. Populations may be defined by any characteristics e.g. where they live, age group, certain diseases. generally consists of an integrated approach (Bus et al, 2016b). Patient education alone for reducing foot ulcer and amputation incidenceThe number of new occurrences of something in a population over a particular period of time, e.g. the number of cases of a disease in a country over one year. has been evaluated in a Cochrane review (Dorresteijn et al, 2014), but the review authors found only small, flawed trialsClinical trials are research studies involving people who use healthcare services. They often compare a new or different treatment with the best treatment currently available. This is to test whether the new or different treatment is safe, effective and any better than what is currently used. No matter how promising a new treatment may appear during tests in a laboratory, it must go through clinical trials before its benefits and risks can really be known. and were unable to draw firm conclusions about intervention effectivenessThe ability of an intervention (for example a drug, surgery, or exercise) to produce a desired effect, such as reduce symptoms.. 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 randomisedRandomization is the process of randomly dividing into groups the people taking part in a trial. One group (the intervention group) will be given the intervention being tested (for example a drug, surgery, or exercise) and compared with a group which does not receive the intervention (the control group).   studies evaluating a variety of complex interventions. Variations between studies precluded meta-analysisThe use of statistical techniques in a systematic review to combine the results of included studies. Sometimes misused as a synonym for systematic reviews, where the review includes a meta-analysis.   and all were at a high or unclear risk of biasAny factor, recognised or not, that distorts the findings of a study. For example, reporting bias is a type of bias that occurs when researchers, or others (e.g. drug companies) choose not report or publish the results of a study, or do not provide full information about a study., 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 outcomesOutcomes are measures of health (for example quality of life, pain, blood sugar levels) that can be used to assess the effectiveness and safety of a treatment or other intervention (for example a drug, surgery, or exercise). In research, the outcomes considered most important are ‘primary outcomes’ and those considered less important are ‘secondary 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:

1. Relief of pressure and protection of the ulcer
2. Restoration of skin perfusion
3. Treatment of infection
4. Metabolic control and treatment of co-morbidityThe presence of one or more diseases or conditions other than those of primary interest. In a study looking at treatment for one disease or condition (for example, heart disease), some of the individuals may have other diseases or conditions that could affect their outcomes (e.g. diabetes).
5. Local wound care
6. Education for patient and relatives
7. 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.

Metabolic control

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.

Treating infection

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 safetyRefers to serious adverse effects, such as those that threaten life, require or prolong hospitalization, result in permanent disability, or cause birth defects.” (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, 2013) 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 standardThe intervention that is widely accepted as being the best available, against which new developments should be compared. For example, a particular medicine., and should be carried out by practitioners with specialist training.

Which dressing?

This is the aspect of treating foot ulcers in people with diabetes on which Cochrane has multiple reviews and an overview of systematic reviewsIn systematic reviews we search for and summarize studies that answer a specific research question (e.g. is paracetamol effective and safe for treating back pain?). The studies are identified, assessed, and summarized by using a systematic and predefined approach. They inform recommendations for healthcare and research. (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 evidenceCochrane Reviews are systematic reviews. In systematic reviews we search for and summarize studies that answer a specific research question (e.g. is paracetamol effective and safe for treating back pain?). The studies are identified, assessed, and summarized by using a systematic and predefined approach. They inform recommendations for healthcare and research. (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 (Liu et al, 2018) found low-certaintyThe certainty (or quality) of evidence is the extent to which we can be confident that what the research tells us about a particular treatment effect is likely to be accurate. Concerns about factors such as bias can reduce the certainty of the evidence. Evidence may be of high certainty; moderate certainty; low certainty or very-low certainty.  Cochrane has adopted the GRADE approach (Grading of Recommendations Assessment, Development and Evaluation) for assessing certainty (or quality) of evidence. Find out more here: https://training.cochrane.org/grade-approach evidence that, compared with dressings, NPWT may increase the proportion of wounds healed and reduce time to healing for post-operative foot wounds in people with diabetes. The IWGDF has 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.

Page last updated 31 December 2018