Amputations in patients with diabetes

A dramatic increase in the number of patients with type II diabetes is being observed worldwide. In the UK, around 2·6 million people are affected, with an expected rise to over 4 million by 2025. A consequent increase in the burden of diabetes-related complications is inevitable. Amputation rates in type II diabetic patients have increased, but not in those without diabetes1. Eighty per cent of patients with diabetes who lose a limb have had a preceding ulcer, and an opportunity for limb and life salvage will have been missed. Identification of patients at high risk of developing foot ulceration is possible using established risk stratification schemes2. In the UK, screening for foot disease in diabetes is performed on an annual basis in primary care as part of the National Health Service framework for assessing quality outcomes. Evidence to support population-based screening and interventions (including structured education programmes) to prevent ulceration, however, remains scant3. In contrast, convincing data demonstrate that multidisciplinary care of patients with ulcerated feet saves limbs4. Guidance documents, designed to reduce risks leading to amputation in diabetic patients, have promoted early recognition of foot disease and suggested rapid assessment by experts in a multidisciplinary setting using evidence-based therapies5,6. Despite these convincing data, effective multidisciplinary teamwork involving vascular surgeons is not always the case. The lack of vascular surgical specialist involvement is of concern. Half of all patients presenting with a foot ulcer have peripheral arterial disease and this proportion is increasing7. Not only is peripheral arterial disease more difficult to diagnose in diabetic patients, in whom symptoms and signs may be masked by neuropathy and incompressible calcified arteries, but it is an independent risk factor for amputation and death. Half of these patients are dead within 5 years. It is important that vascular surgeons work with other healthcare professionals and patient groups to establish local pathways of care to ensure that patients with diabetes and ischaemic, infected and ulcerated feet are triaged and referred appropriately. A recent Department of Health ‘map of medicine’ and other studies have revealed considerable variation in amputation rates in England8,9. Limb-saving revascularization procedures are not being performed in significant proportions of patients with diabetes, ulcerated feet and severe peripheral arterial disease. The Eurodiale study of 1232 patients with diabetes and a newly presenting foot ulcer in 14 centres throughout Europe found that only 50 per cent of patients with an ankle : brachial pressure index (ABPI) less than 0·5 underwent adequate vascular evaluation and subsequent revascularization10. Trends for lower rates of revascularization have also been noted in the UK over a 15-year interval in patients with diabetes11. The reasons are unclear but may reflect surgical decision-making, the anatomical distribution of peripheral vascular disease, the severity of tissue loss at presentation and associated co-morbidities. It is disturbing that this situation should exist in the presence of validated scoring systems that predict outcome from foot ulcers in patients with diabetes, and after revascularization in patients with critical limb ischaemia12,13. Endovascular techniques that can be applied to these patients are improving with the introduction of technology developed in the coronary circulation, particularly suited to small and calcified vessels. In expert hands, high rates of successful revascularization can be achieved14, although there have been no randomized trials to indicate the most appropriate method of revascularization in patients with ulceration of the foot and diabetes. A recent systematic review suggested that rates of limb salvage in patients undergoing endovascular and bypass surgery were broadly similar in patients with diabetes15. At present it would appear that the choice of intervention is probably less important than the decision to intervene and its timing. Current evidence also suggests that high-volume vascular centres achieve better results from vascular reconstruction, but it is not clear whether they attempt revascularization more frequently16. Prompt surgical debridement of infected ischaemic tissue remains an important adjunct to treatment and saves limbs17. Conversely, chronic osteomyelitis, once thought to be a surgical disease, may now be managed successfully in most patients with prolonged courses of antibiotics. Many of the latest and most expensive dressings, including those containing silver, have consistently failed to demonstrate efficacy in the most robust clinical trials18. There are, however, well constructed studies that support the use of negative-pressure wound therapy in patients with surgically created acute wounds. A recent single-centre double-blind randomized trial also suggested that hyperbaric oxygen might be effective in healing some wounds19. Difficulties in interpreting the literature related to diabetes, foot ulceration and arterial disease remain. There are no standard reporting criteria, making comparison of interventions difficult. In any patient the severity of peripheral arterial diseases may range from relatively mild disease with a limited effect on wound healing to severe limb ischaemia with delayed wound healing and a high risk of amputation. Using the established TransAtlantic InterSociety Consensus II Classification (TASC II), all of these patients are considered as having ‘critical limb ischaemia’. Furthermore, wound healing may be impaired by a complex interplay of factors including poor glycaemic control and microvascular dysfunction. The contribution of underlying arterial disease to wound healing will therefore relate in part to its severity and extent, but also to these other factors. Standard trial endpoints such as limb salvage may also be less relevant in patients with diabetes. Quality-of-life studies suggest that ulcer healing may be just as important an endpoint. Many surgeons, particularly those involved in vascular surgery, are likely to be confronted regularly with patients suffering from diabetes-related foot disease. A coordinated (evidence-based) approach to patient care with other members of a multidisciplinary team, including rapid assessment of associated peripheral arterial disease, early debridement and revascularization, will reduce amputations and save lives. The author declares no conflict of interest.