Examining The Evidence For Preventing Diabetic Foot Ulcers
Q: What does evidence-based medicine show in regard to who is at risk for limb loss and foot ulcerations?
A: Thomas Zgonis, DPM, says approximately 15 percent of patients with diabetes will experience a diabetic foot ulcer (DFU).1,2He says some of the most significant risk factors for DFUs and subsequent lower extremity amputations (LEA) are multiple systemic complications that are caused by chronic hyperglycemia. Citing different studies, Dr. Zgonis says significant predictors for the development of a DFU include poor glycemic control, impaired vision, progressive foot deformities with abnormal pedal pressures and minor repetitive trauma to the insensate foot.2-5
Dr. Zgonis, Nicholas Bevilacqua, DPM, and Kazu Suzuki, DPM, cite peripheral arterial disease (PAD) as a predictor for ulceration. Dr. Bevilacqua says PAD is a part of the University of Texas Diabetic Foot Risk Classification, the levels of which range from risk category 0 (patients with diabetes but no neuropathy or PAD) to level 3 (patients with a history of ulceration, amputation or Charcot foot).6
However, Dr. Bevilacqua says this classification system may have undervalued PAD. Lavery, et al., modified the University of Texas system and he says their classification includes PAD but not deformity.7
“This modified classification system predicts future foot complications better than the previous one,” says Dr. Bevilacqua.
Peripheral arterial disease and critical limb ischemia (CLI) are “by far” the major cause of limb loss in the United States, according to Dr. Suzuki. He cites data from the Trans-Atlantic Inter-Society Consensus (TASC-II) guideline 2007, which notes that risk factors for developing CLI (and subsequent limb loss) are diabetes (a fourfold risk), smoking (a three-fold risk), and age over 65 (twice the risk).8
In regard to patients with risk factors for PAD or leg complains (fatigue, cramps, claudication), Dr. Suzuki says the TASC-II guidelines encourage physicians to evaluate leg pulses and utilize “objective testing” such as ankle brachial index and skin perfusion pressure. TASC-II also advocates objective testing for PAD in “all diabetic patients with an ulceration,” according to Dr. Suzuki. He adds that the TASC-II guidelines also emphasize PAD testing for suspected CLI patients with rest pain and pedal ulcers, including gangrenous toes.8
Dr. Suzuki also emphasizes the TASC-II conclusion that, “Early identification of patients with PAD at risk of developing foot problems is essential for limb preservation. This can be achieved by daily visual examination by patient or (his or her) family and, at every visit, referral to the foot specialist.”8 Similarly, Armstrong, et al., suggested that up to 85 percent of amputation may be prevented by early detection and appropriate treatment of foot ulcers.9
A history of previous ulceration or amputation is another risk factor for ulceration and limb loss, according to Dr. Zgonis, Dr. Bevilacqua, Lawrence Karlock, DPM, and Geoffrey Habershaw, DPM.10
Dr. Zgonis also notes that patients with diabetes are about 15 to 40 times more likely of undergoing a non-traumatic LEA compared to non-diabetic patients.2,11 Certain ethnicities, older patients and male patients are also at higher risk, according to Dr. Zgonis.2,3,12,13
Dr. Karlock cites research by Pham, et al., who concluded that the clinical exam and the 5.07 Semmes-Weinstein monofilament test were the two most sensitive tests for identifying patients at risk for ulceration.14 He notes the study also concluded that foot pressure measurements offered a high degree of specificity and one can use them as a post-screening test along with providing appropriate footwear.14