Other reported sources of trauma precipitating foot ulceration include rubbing from footwear and as a consequence of surgery. Macfarlane & Jeffcoate (1997) reported that rubbing from footwear was the most common precipitant (20.6%) in a prospective study of 669 ulcers seen in a multidisciplinary foot clinic. Trips and falls have also been identified as contributors to foot ulceration and the National service framework for older people has stated the aim is to reduce the number of falls which result in serious injury (Department of Health 2001). This initiative may help in the reduction of foot wounds in the at-risk population.

There is a substantial body of evidence that has identified the risks of ulceration in the diabetic population. Whilst there are other at-risk groups, people with diabetes are considered to have the greatest risk of ulceration. Approximately 2–3% of individuals with diabetes develop one or more foot ulcers each year and an estimated 15% will develop a foot ulcer during their lifetime (Frykberg et al 1998). Foot ulceration impacts on the individual’s functional ability and quality of life (Price & Harding 2000). Pecoraro et al (1990) demonstrated that in more than 80% of cases, amputation was preceded by a foot ulcer. The economic burden is high with an estimated £244 million spent in 2001 on foot ulcers and amputations in the UK (Gordois et al 2003).

Risk factors in diabetic foot ulceration

It is important to be able to identify the most significant risk factors that predispose the diabetic person to foot ulceration. Similarly it is imperative to identify and evaluate the risk factors that may affect the prognosis and outcomes of such wounds. This process will aid the healthcare practitioner to develop a care pathway with appropriate referral criteria to other healthcare agencies. Many researchers have identified causal pathways and risk factors for ulceration. Targeting modifiable risk factors can reduce the incidence of foot ulcers or amputations (Malone et al 1989, Uccioli et al 1995).

The risk factors that are most commonly found in the causal pathway to a foot ulcer are:

• neuropathy

• peripheral arterial disease

• deformity (Reiber et al 1999).

A pivotal prospective study in a North American Indian population (Rith-Najarian et al 1992) identified risk factors that were predictive for foot ulceration. These included:

• structural foot deformity (hallux valgus or varus, claw and hammer toes, bony prominence or Charcot foot)

• peripheral neuropathy

• history of previous ulcer or amputation.

In this study, the researchers found that an ulcer was about five times more likely to occur in a patient with a history of disease or lack of sensation than in a patient without these factors. In another prospective study, Boyko et al (2006) followed 1285 diabetic subjects without foot ulcer (mostly male) over 3 years (mean 3.38). Significant predictors of foot ulcers included: impaired vision, prior foot ulcer, prior amputation, monofilament insensitivity, tinea pedis and onychomycosis. Merza & Tesfaye (2003) in a review of risk factors for diabetic foot ulceration describe other identified risk factors (Box 18.1).

Box 18.1 Risk factors for diabetic foot ulceration

• Diabetic neuropathy

• Peripheral vascular disease

• Biomechanical factors

• Previous foot ulceration

• Poor glycaemic control

• Long duration of diabetes mellitus

• Race

• Smoking

• Retinopathy and nephropathy

• Insulin use and poor vision

• Age and male sex

• Other factors

Other identified risk factors

• Old age

• Oedema

• Renal disease

• Psychosocial factors

• Obesity

• Previous history of ulceration

• Ill-fitting footwear

• Limited joint mobility

• Presence of skin callus

• Self-treatment

• Social isolation

• Social deprivation

Screening

Screening for risk factors for ulceration is recommended by various national and international guidelines (Scottish Intercollegiate Guidelines Network 2001, National Institute for Clinical Excellence 2004) and is an important part of a primary prevention programme. However, it may not be a cost-effective activity if the whole diabetic population has to be screened in order to identify the ‘at-risk’ group of patients. Any screening programme has to be carefully considered and the resources have to be identified. The implications and consequences of screening programmes are far-reaching and will impose a significant burden of the health economy. Identification of risk factors may be important, however, it may be considered even more important that prevention programmes can achieve their aims.

International guidelines suggest that people with diabetes should be examined for potential foot problems at least once a year (Apelqvist et al 2007). The Consensus on the Diabetic Foot suggests a risk categorisation system should be adopted with a recommended check-up frequency (see Table 18.1).

Table 18.1 Risk categorisation system

Category	Risk profile	Check-up frequency
1	No sensory neuropathy	Once a year
2	Sensory neuropathy	Once every 6 months
3	Sensory neuropathy, signs of peripheral arterial disease and/or foot deformities	Once every 3 months
4	Previous ulcer	Once every 1–3 months

There is evidence that the identification of the risk category can predict an episode of ulceration (Leese et al 2006). This may help to target resources to the appropriate patient groups. Numerous guidelines have suggested reliable tools to use in the identification of peripheral neuropathy and the presence of arterial disease (Best practice pathway 2007). However, there remains debate about the number of test sites required to ascertain loss of protective sensation. Table 18.2 gives the clinical tests used to identify risk based on best available evidence. In addition, a medical history to assess other risk factors, e.g. history of ulceration, will be required. There are other methods to determine extent of neuropathy, e.g. the Neuropathy Disability Score (Boulton 2005), but for a simple screening tool, the above tests are recommended.

Table 18.2 Simple identification of risk factors

	Sites
DEGREE OF SENSORY NEUROPATHY
Loss of protective sensation (10 g nylon monofilament)	Pressure sites of plantar aspect of the hallux, 1st and 5th metatarsal heads of both feet
Loss of vibration perception (128 Hz tuning fork) or vibration perception threshold (neurosthesiometer)	Distal end of hallux and medial and lateral malleolus Same sites above >25 V
PERIPHERAL ARTERIAL DISEASE
Absence of two or more pedal pulses	Dorsalis pedis and tibialis posterior pulses
Ankle–brachial pressure index	Both dorsalis pedis and posterior tibial pulses
OBSERVATION OF FOOT DEFORMITY	Hallux abductovalgus, hallux rigidus, pes cavus pes planus and Charcot’s foot deformity
Limited joint mobility syndrome	Positive prayer sign (see Fig. 18.2)
Observation of plantar callus	Pressure points of hallux, all metatarsophalangeal joints, apices of digits and heels of both feet

Having a history of a previous ulcer is a significant risk factor for a recurrence (Abbott et al 2002, Boyko et al 1999, Peters et al 2001). In an important publication by Frykberg et al (1998) of the 251 patients studied, 99 patients had a current or prior history of ulceration, and 33 with active ulcers. Recurrence rates have been reported to range from 28% at 12 months (Chantelau et al 1990) to 100% at 40 months (Uccioli et al 1995). Apelqvist et al (1993) reported a recurrence rate of 34% and 70% after 2 and 5 years, respectively. Clearly having had a history of ulceration is the most important risk factor for further ulceration.

Renal failure

Identification of risk factors does not only inform the practitioner who is at risk, but also informs treatment options and likely prognosis. For example the diabetic patient with end-stage renal failure and peripheral arterial disease who presents with a foot ulcer has a high risk of infection and a poor prognosis (Boufi et al 2006).

Figure 18.2 Limited joint mobility as demonstrated by the prayer sign.

Established renal failure in diabetes is associated with a high incidence of foot ulcers and gangrene. This problem may be particularly associated with the onset of renal replacement therapy. There is evidence that haemodialysis causes hypoxaemia and this can be reflected in the subsequent decrease in lower limb transcutaneous oxygen tension (TcPO₂) (Hinchcliffe et al 2006). These patients are liable to be prescribed immunosuppressant drugs and are therefore at great risk of infection. This patient group will have underlying advanced diabetic microangiopathy and often have concomitant peripheral arterial disease and are hypertensive. Clearly, a holistic assessment of all of the risk factors is needed to evaluate risk factor status for possible future ulceration.

Practice point

Chronic renal insufficiency can be identified by the following criteria: creatinine >4.0 mg/dl, current dialysis or a history of renal transplantation (Savage et al 1996).

Biopsychosocial approach

Following a primary screening programme, patients may be referred to a podiatrist for further assessment, education and treatment if required. Many of the at-risk patients may be over 50 years of age and suffer from other co-morbidities. A comprehensive assessment is needed to have a full appreciation of the patient’s life, their heath beliefs and behaviours, risk of developing a wound and likely prognosis. In addition any negotiated care plan will have been informed by a full assessment. It may be helpful to consider the following factors.

Psychosocial factors

Recognition of the importance of both psychological and social factors in the care of people with diabetes is required to assess and facilitate optimum management. Neuropathy, pain, foot ulceration and amputation can have a devastating effect on the person with diabetes. This may lead to social isolation, depression and failure to maintain healthy behaviours. As a consequence there may be a downward spiral of poor health, further complications and early death (Vilekyte et al 2003).

The quality of life can be severely affected by the complications of neuropathy and foot ulceration. The psychosocial assessment of patients suffering from these complications is vital to determine further risk of the complications and improve care. A seminal research study by Vilekyte and colleagues (2003) led to the development of a validated quality-of-life instrument (NeuroQoL) that can reliably capture the key physical and psychosocial effects. Psychosocial factors that are measured include disruption of daily living and interpersonal-emotional burden. Healthcare practitioners should consider the use of this assessment tool to inform any behavioural strategy and evaluate effectiveness of quality of care.

The podiatrist and other healthcare providers have to develop the skills and knowledge in order to embrace a biopsychosocial approach to caring for the at-risk diabetic person (Kinmond et al 2003). Psychological and emotional wellbeing is the foundation on which all other aspects of the treatment regimen rest and failure to consider these aspects in management of the diabetic foot can lead to poor outcomes (Clark 2006).

The psychological and social barriers to diabetes self-management and quality of life are given below.

Psychological factors

• Low levels of self-efficacy

• Personal illness models and health beliefs

• Depression.

Social factors

• Stress

• Low levels of support from family and close friends.

Albert Bandura first described self-efficacy in 1977 and recognised that it is a key psychological factor that influences a wide range of health behaviours. In essence, self-efficacy is a belief in one’s own ability that by carrying out a set of actions, one will achieve the desired goals. In the context of the high-risk diabetic patient, if he or she strongly believes that by carrying out certain foot health preventive practices, foot ulceration will be prevented, then they are more likely to adhere to those healthy behaviours. Conversely, if the high-risk patient has low self-efficacy, and does not hold those aforementioned health beliefs, then it is unlikely that they will adopt healthy footcare practices.

Motivational interviewing

Assessment of psychosocial factors requires good communication skills that lead to developing a rapport with patients. Once a relationship has been established, the patient’s self-efficacy can be explored. It is not the purpose of this chapter to expand on the psychology of diabetes. However, the assessment of health beliefs, attitudes and self-efficacy do need to be explored.

Hampson and colleagues (1996) have shown that personal models of diabetes, e.g. beliefs about the consequences of having diabetes and the effectiveness of treatment can predict self-care behaviour. It is therefore important to explore with the person with diabetes or other chronic illness about their perceptions of how their illness affects them. This holistic approach to assessment needs to include an exploration of the patient’s perceived susceptibility to their illness and foot complications. It is only by adopting an empathetic approach and willingness on behalf of the patient to disclose such information that valuable insights may be gained to facilitate change in self-management.

Practice point

Consider the following assessment strategy: use of open ended questions, e.g. ‘How are you today, Mrs Smith?’ or ‘How have you been getting on with your insoles?’. This approach needs to be accompanied by affirmation, e.g. ‘Well done for making your appointment today and well done for trying out the insoles.’ It is important to be sincere and genuine with questioning and praise. If not, the practitioner may be perceived as patronising and this will result in failure to establish a rapport. It is vital that active listening is adopted. The patient may be trying to disclose other information.

At this stage, some summarising can be very helpful. This demonstrates that the practitioner has been listening and gives the patient an opportunity to reflect on what has been said. The patient-centred approach is best practice and will enhance the assessment process.

Self-efficacy can be explored by a skilled practitioner. Consider the following: ‘How important is it for you Mrs Smith to get the ulcer healed on your foot? On a scale of 1–10, 1 representing not at all important and 10 being very important?’. Many patients will consider it to be very important and score highly.

This can lead to the practitioner asking the following: ‘On a scale of 1–10, how confident are you that by sticking to your treatment plan, the ulcer will heal?’ The response may shed some light into the self-efficacy of Mrs Smith. She may score a 2. This provides the practitioner the opportunity to praise the 2 scored, and enquire why Mrs Smith did not score a zero. The dialogue that follows allows the patient to reflect on her beliefs about her confidence and consider what it might take to move along the scale.

These are simple tools that practitioners may consider to enhance the assessment process. This patient-centred approach has been recommended (Lincoln et al 2007) and is a key part of the assessment process. In addition many of the at-risk patients may well have depression, which will affect their health behaviours and communication. All practitioners should consider that diabetes doubles the risk of depression (Anderson et al 2000).

Assessment of foot health knowledge and behaviour is often overlooked as part of the assessment process and yet it is often the health behaviours that lead to an episode of ulceration and further recurrence. One new assessment tool that has been validated is the Nottingham Assessment of functional Footcare (NAFF). This questionnaire explores both knowledge and behaviour and could be used to test the effectiveness of education and identify specific areas of poor protective behaviour that individuals may have (Lincoln et al 2007).

Other useful health-related quality of life and diabetic foot ulcer assessments include:

• The Diabetic Foot Ulcer Scale (DFS): a quality of life instrument for use in clinical trials (Abetz et al 2002).

• The Diabetic Foot Ulcer Scale – short form (DFS-SF) (Bann et al 2003).

Socioeconomic factors

Many of the leading causes of mortality and morbidity are related to low socioeconomic status. Individuals with low socioeconomic status suffer from more diseases and their consequences than from those who enjoy higher socioeconomic status (Alder et al 1993). Studies have shown that low socioeconomic status is associated with obesity, depression and diabetes (Everson et al 2002). The relationship is complex and there is evidence that those with low socioeconomic status have a greater prevalence of smoking, higher alcohol consumption, poorer diets and more sedentary lifestyles. These health behaviours are more likely to put the person at greater risk of developing the chronic disorders stated.

Socioeconomic factors are not routinely assessed in clinical practice and are more likely to be explored in research studies. However, it may be useful to consider these socioeconomic factors as they may impact on your assessment and management of the at-risk foot:

• Social class (occupation).

Although it has been acknowledged that poor socioeconomic status is a risk factor for diabetic foot complications (Apelqvist 2000), the evidence is fairly sparse. The at-risk population tend to be older, and there are some difficulties in measuring socioeconomic factors with this group. As an example, social class measured by occupation is not possible with a retired population. The lower-limb practitioner should take into account the socioeconomic status of the patient as this may inform the assessment and prognosis. In addition, the practitioner may be able to refer the patients to other agencies, for example social services, voluntary support for further assistance.

Age

The ageing population in the UK and other developing countries is well acknowledged and statistics from Help Age International suggest there are 550 million older people worldwide, which will increase to 1.2 billion by 2025 (Help Age International 2005). With this demographic background and an expected increase in the prevalence of diabetes, the proportion of at-risk patients will increase substantially. In the context of the at-risk foot, tissue viability may be compromised by the ageing process. The ageing process is a complex process and can be divided into intrinsic and extrinsic ageing.

Intrinsic ageing is mostly genetically determined and extrinsic ageing, more commonly referred to as photoaging, is caused by environmental exposure in the form of ultraviolet radiation (Fisher et al 2002). These aging processes have both qualitative and quantitative effects on collagen and elastic fibres in the skin (El-Domyati et al 2002). Although the pathomechanisms of collagen deficiency differ between intrinsic and extrinsic ageing, the cumulative effects result in dermal atrophy and decrease in the elasticity of the skin (Tzaphlidou 2004).

Wound healing and repair processes decline with age and the inflammatory response, proliferative phase and maturation have all been shown to alter with age (Hardy 1989). Growth factors and their receptors which regulate the wound healing process are also affected by the ageing process (Ashcroft et al 1997). The aged skin is at greater risk of damage and wound dehiscence occurs more frequently in people over the age of 60 (Falanga & Eaglstein 1988).

The main contributing risk factors that can lead to the development of ulceration, infection and gangrene have been identified. However, a number of both local and systemic factors may affect wound healing and facilitate infection (Table 18.3).

Table 18.3 Conditions which may affect healing

Category	Examples
Cardiovascular	Peripheral arterial disease, venous insufficiency, lymphatic obstruction
Endocrine	Diabetes, malnutrition, deficiency syndromes, obesity
Immunological	DiGeorge syndrome, hypogammaglobulinaemia, human immunodeficiency virus infection, rheumatoid arthritis and hypersensitivity
Immunosuppressive agents	Long-term steroids, immunosuppressive drugs, radiation, cytotoxic drugs
Infectious	Cytomegalovirus, infectious mononucleosis, bacterial and fungal agents
Haematological	Luekaemia, anaemias, haemophilia, sickle-cell anaemia
Musculoskeletal	Deformities, hypermobility
Neoplasia	Carcinoma, lymphomas, sarcomas
Respiratory	Chronic obstructive airways disease
Renal	Chronic nephropathy
Traumatic	Burns, foreign bodies, repeated minor trauma, tight hosiery
Exogenous factors	Inappropriate dressings, antiseptics, harsh environment, caustics and irritants