News Author: Laurie Barclay, MD
CME Author:Désirée Lie, MD, MSEd
June 1, 2010 — Dialysis treatment is independently associated with foot ulceration in patients with diabetes and stage IV or V chronic kidney disease (CKD), according to the results of a cross-sectional study reported online May 18 in Diabetes Care.
“Foot ulceration is a serious problem for people with diabetes which additionally results in huge economic costs,” write Agbor Ndip, MD, from Central Manchester University Hospitals NHS Foundation Trust in Manchester, United Kingdom, and colleagues. “Causal pathways to foot ulceration are multifactorial and involve combinations of physiologic and mechanical factors, self-care and treatment factors. Diabetic nephropathy has been identified to be an important risk factor for foot ulceration and amputation.”
The goal of the study was to examine whether dialysis is an independent risk factor for foot ulceration in 326 consecutive patients with diabetes and stage IV or V CKD who were attending clinics in Manchester. Mean age was 64 years, 61% were men, 78% had type 2 diabetes, and 11% had prevalent foot ulceration.
Patients receiving dialysis treatment and those not receiving dialysis were evaluated for diabetic peripheral neuropathy (DPN), peripheral arterial disease (PAD), prior foot ulceration and amputation, and foot self-care. Logistic regression identified risk factors for prevalent foot ulceration.
Patients receiving dialysis had a higher prevalence of DPN vs patients not receiving dialysis (79% vs 65 %), PAD (64% vs 43%), prior amputations (15% vs 6.4%), prior foot ulceration (32% vs 20%), and prevalent foot ulceration (21% vs 5%; all P < .05). Factors associated with foot ulceration in univariate analyses were use of custom-made footwear (odds ratio [OR], 5.6; 95% confidence interval [CI] 2.5 – 13), dialysis (OR, 5.1; 95% CI, 2.3 – 11), prior foot ulceration (OR, 4.8; 95% CI, 2.3 – 9.8), PAD (OR, 2.8; 95% CI 1.3 – 6.0), and years of diabetes (OR, 1.0; 95% CI, 1.0 – 1.1; P < .01 for all).
However, the only factors associated with prevalent foot ulceration in multivariate logistic regression were dialysis treatment (OR, 4.2; 95% CI, 1.7 – 10; P = .002) and prior foot ulceration (OR, 3.1; 95% CI, 1.3 – 7.1; P = .008).
“Dialysis treatment was independently associated with foot ulceration,” the study authors write. “Guidelines should highlight dialysis as an important risk factor for foot ulceration requiring intensive foot care.”
Limitations of this study include cross-sectional design, precluding inference about causal relationships; lack of generalizability to nonwhite ethnic groups; insufficient power to compare the site of foot ulceration in dialysis and no-dialysis groups. In addition, the site and severity of peripheral edema and the severity of PAD were not systematically evaluated.
“Our findings have important clinical implications as they alert health care practitioners that dialysis is an independent risk factor for foot ulceration thus requiring extra vigilance and foot care,” the study authors conclude. “Current diabetes guidelines and recommendations fail to recognise the strength of the link between dialysis-treatment and foot ulceration. Our findings suggest that in terms of foot ulcer risk, dialysis treatment should be ranked equivalent to a history of previous foot ulceration (i.e. risk category 3, IWGDF [International Working Group on the Diabetic Foot] classification [risk 0 (no risk factors), risk 1 (neuropathy and no other risk factors), risk 2 (PAD with/without neuropathy), risk 3 (current foot ulcer, history of foot ulcer or amputation), and risk 4 (current foot ulcer, history of foot ulcer, or prior amputation)]).”
Diabetes UK supported this study, as well as the Manchester NIHR Biomedical Research Centre and the Manchester Academic Health Science Centre. Some of the study authors have disclosed various financial relationships with Higher Education Funding Council for England; National Institutes of Health; KCI; Diabetica Solutions; LaseCure; National Healing; Advanced Biohealing; Pfizer; Cytomedix, Inc; and/or Diabetic Solutions.
Diabetes Care. Published online May 18, 2010.
Clinicians can educate their diabetic patients about proper foot care using the Diabetes – Foot Care online tutorial from MedlinePlus.
The lifetime risk for foot ulceration in patients with diabetes is 25% and risk factors include mechanical, physiologic, and self-care issues. It is uncertain how the need for dialysis affects the risk for foot ulcers in diabetic patients.
This is a cross-sectional study of consecutive patients with stage IV or stage V CKD and diabetes to examine the influence of dialysis on the prevalence of foot ulcers and other foot pathologic conditions.
- The study involved consecutive patients attending one of 2 diabetes and renal dialysis centers in Manchester, United Kingdom, between 2006 and 2008.
- Stage IV or V CKD was defined as average Modification of Diet in Renal Disease estimated glomerular filtration rate of less than 30 mL/minute for the preceding year.
- Patients were classified into 2 groups: no dialysis and dialysis (either hemodialysis or peritoneal dialysis).
- At clinic visits, data were collected by clinicians and from medical records.
- Medical history including a history of foot ulcers, bypass surgery, retinopathy, and a history of dialysis was determined.
- The researchers elicited foot self-care from the patients by asking 4 questions about use of custom-made footwear or insoles, regular visits to a podiatrist, walking barefoot, and daily foot inspection.
- DPN was assessed with measurement of vibration perception threshold with a neurothesiometer and clinical examination with use of the modified neuropathy disability score.
- The researchers assessed PAD using the posterior tibial and dorsalis pedis pulses bilaterally, the ankle brachial index using a Doppler ultrasound probe in both legs, and using medical records to identify angiographically diagnosed PAD.
- Major amputations were defined as those proximal to the ankle and minor amputations as through or distal to the ankle joint.
- Foot deformity was defined by the examining physician as hallux valgus, claw or hammer toes, prominent metatarsal heads, and dislocated metatarsophalangeal joints.
- 4 levels of increasing foot risk were identified with the International Working Group on the Diabetic Foot classification, from 0 (no risk factors) to 4 (current foot ulcer, history of foot ulcer, or prior amputation).
- 326 patients were assessed (139 in the dialysis group and 187 in the no-dialysis group).
- In the dialysis group, 61% were treated with hemodialysis.
- Mean age was 56 years for the no-dialysis group and 64 years for the dialysis group.
- Most were white, less than 20% were Asian, more than 75% had type 2 diabetes, and mean duration of diabetes was 20 years.
- 70% also had retinopathy, 11% had foot ulcers, and 10% had had a prior lower limb amputation.
- The difference in prior amputation rate was not significant between the dialysis group and the no-dialysis group (65% and 58%, respectively).
- Patients receiving dialysis were younger, more likely to have type 1 diabetes, and more likely to have a lower serum albumin concentration.
- Dialysis treatment was associated with a 5-fold higher prevalence of prevalent foot ulcers and a 2-fold higher risk for prior amputation, prior foot ulceration, DPN and PAD, and a lower risk for foot deformity.
- Patients receiving dialysis were 3 times more likely to be classified as high risk (score of 4) on the International Working Group on the Diabetic Foot classification.
- Rates of foot ulceration were similar in the dialysis group who received hemodialysis vs peritoneal dialysis.
- Although prevalent foot ulceration was positively linked to wearing custom-made footwear, dialysis, PAD, duration of diabetes, and attendance at podiatry clinic, only dialysis and a history of foot ulceration were independent predictors after accounting for variables.
- The authors recommended that diabetic patients who start receiving dialysis have intensive education on the prevention of foot ulceration and that additional interventions are needed to prevent such ulcers.
3. Clinical Implications
Dialysis in patients with diabetes is associated with a higher prevalence of prevalent foot ulcers, prior amputation and foot ulceration, DPN, and PAD.
Dialysis and a history of foot ulceration are independent predictors of prevalent foot ulcers in patients with diabetes.