In two recent issues of Diabetes Care, high amputation rates among Maori people from New Zealand (1) and Native Americans (2) with diabetes on dialysis were reported. We would like to add some information concerning Caucasians with diabetic foot syndrome and advanced renal disease from a prospective sample of 400 consecutive patients treated at our diabetic foot clinic. Similar to chronic renal insufficiency (defined by serum creatinine concentration 1.5–3.0 mg/dl), chronic renal failure and end-stage renal disease (ESRD) should be regarded as a continuum (3). We analyzed the frequency of these conditions among the entire study population and compared presentation features and outcomes among the concerned patients and among diabetic foot patients without obvious renal impairment.
At the time of presentation for the index foot lesion, 14 patients (4%, group A) were on dialysis, 72 patients (18%, group B) suffered from chronic renal insufficiency (serum creatinine ≥1.5 mg/dl), and 314 patients (78%, group C) had no signs of advanced renal impairment.
There were no significant differences among the groups regarding age, diabetes duration, or quality of metabolic control. The proportions of underlying neuropathy (86, 91, and 79%, respectively) and peripheral vascular disease (71, 56, and 50%, respectively) were higher among patients with renal impairment but not significantly different from the proportions of patients with normal renal function. However, the coincidence of peripheral vascular disease (PVD) and neuropathy was far more common in diabetic patients on dialysis than in patients without renal impairment (71% in group A vs. 36% in group C, P = 0.015); therefore, patients on dialysis are at even higher risk for unrecognized nonhealing foot lesions. Coexistence of PVD and mediasclerosis was also far more frequent in the dialysis group than in the other two groups (80 vs. 26 and 34%, P = 0.01 and P = 0.003).
Total amputation rate was 57% for dialysis patients and was therefore significantly higher than that among patients with chronic renal insufficiency (25%, P = 0.006) or patients without obvious renal impairment (16%, P < 0.001). This was primarily caused by a sixfold increased risk of major amputation of dialysis patients compared with patients with normal renal function (29 vs. 4.5%, P < 0.001). One-year survival was poor among diabetic patients on dialysis with foot lesions compared with their counterparts without renal impairment (71 vs. 94%, P = 0.007). However, a higher proportion of patients in the dialysis group were suitable for vascular intervention compared with the other two groups (46 vs. 14 and 13%, P = 0.02). After successful revascularization, the risk of consecutive major amputation was similar in all three groups (17, 20, and 16%, respectively). This last finding is in contrast to previous publications (4,5,6,7) that indicated an increased risk of amputation even in the presence of patent grafts after revascularization among ESRD patients, caused by nonhealing large foot ulcers and uncontrolled infection. The better outcome in our series of diabetic patients on dialysis with foot lesions might be explained by the structured interdisciplinary inpatient care after surgery, as well as the continued care by the diabetic foot clinic after hospital discharge. This interpretation is supported by the observations of Foster et al. (8), who showed that care by a special diabetic foot clinic reduces episodes of digital gangrene and major amputation in diabetic renal transplant patients.
In conclusion, Caucasian patients with diabetes on dialysis are at high risk for amputation once a foot lesion occurs. However, vascular interventions should not be refused to those patients if structured interdisciplinary inpatient care after surgery and long-term follow up by a special diabetic foot clinic are available. Prevention of foot complications among diabetic patients with ESRD and prognosis improvement in the case of an established foot lesion should be targeted by intense collaboration of dialysis units and specialized diabetic foot centers.
References
Address correspondence to Stephan Morbach, MD, Department of Internal Medicine, Marienkrankenhaus, Widumgasse 5, 59494 Soest, Germany. E-mail: [email protected].
