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Researchers help diabetics keep their feet and legs (9/30/97)

Ten dollars worth of monofilament wire, a gadget that costs as little as $400, and a set of carefully-worded questions are helping physicians prevent scores of leg amputations and save millions of dollars in health care costs. With these simple tools, health care providers can determine which diabetic patients are at increased risk for foot ulceration, infection and subsequent amputation.

"The chief ingredient in the recipe for amputation in patients with diabetes is lack of feeling," said David Armstrong, DPM, podiatrist and assistant professor in the department of orthopaedics at The University of Texas Health Science Center at San Antonio, who led a recent case- control study investigating practical screening of diabetic feet. "Virtually every diabetic experiences a loss of sensation, especially in the feet--that's called peripheral neuropathy," he added.

"If you or I experienced foot pain, we'd change the way we walk. A diabetic, not feeling that pain, would keep walking on the deformed area until a blister or sore developed and then got infected," Dr. Armstrong added. Frequently this problem is compounded because numerous patients do not regularly examine their feet, Dr. Armstrong explained. If left untreated, the infected sores can lead to leg amputations.

Dr. Armstrong and research team members Drs. Lawrence Harkless, professor, and Lawrence Lavery, assistant professor, use the monofilament wire and a vibration perception device to determine the point at which diabetic patients do not experience enough pain to protect their feet. "There's a big spectrum of neuropathy (nerve degeneration)," explained Dr. Armstrong. "The loss of sensation and inability to feel pain progress slowly."

To determine a patient's place on the neuropathy spectrum, the podiatrists apply an easy-to-use, inexpensive Semmes-Weinstein monofilament wire to specific sites on diabetic patients' feet with about 10 grams of force. "If they cannot feel that amount of force, then they could wear a hole in their skin, just like you or I could wear a hole in a stocking," Dr. Armstrong said. Questions about what a patient may or may not be feeling during the application of the wire and the correct way of asking those questions, according to the podiatrist, have been very vague in the past. His group has focused on developing specific questions and accurately interpreting patients' answers.

The other device used in the study is a biothesiometer. "The biothesiometer is applied to the foot and it rests on the big toe. The power is gradually turned up until the patient feels the vibration. Patients who cannot feel 25 volts are at significantly higher risk of developing ulceration. This test is greater than 90% sensitive,'' Dr. Armstrong explained.

The monofilament wire, biothesiometer, and focused questions in a good patient history can yield 100% accuracy in determining which patients are at risk for foot ulceration, Dr. Armstrong said. "Our goal is to keep more legs on more bodies. These low-tech testing methods, while extraordinarily easy to perform, are not taught with any regularity at the majority of our nation's medical and indeed at some podiatric medical colleges. This must change if we are to see any reduction in lower extremity amputations in North America," Dr. Armstrong added.

Their screening study was presented this summer at the annual American Diabetes Association Scientific Symposium in Boston. "There's no question that identifying these people early, allocating resources for them, scarce resources, is of critical importance," Dr. Armstrong said. ''We want to find out where all these people lie on the neuropathy spectrum and place them in the appropriate risk category, and allocate resources for them."

The same podiatric team presented a review of 2,000 diabetes-related amputations in South Texas at the International Diabetes Federation meeting in Helsinki, Finland, in July. Dr. Armstrong described their findings as "startling."

"While only 2% of patients receiving an amputation were admitted from a long-term care facility, more than one quarter were discharged to one following their amputation," Dr. Armstrong said. This data indicates that the short-and medium-term costs incurred following a diabetes- related lower extremity amputation are perhaps considerably higher than previous estimates.

"Direct cost associated with these procedures is most definitely not the most important issue here," Dr. Armstrong said. "Many of these patients were admitted to the hospital as ambulatory, productive members of society. Far too many are leaving with a different capacity altogether."

Each year the Health Science Center podiatry group sees approximately 14,000 patients. Many of those are diabetic and considered high risk. With these new, low-cost evaluation procedures, physicians can help prevent foot ulcerations which could lead to costly, debilitating amputations.

Results from these studies will be published in the *Archives of Internal Medicine* and *American Journal of Medicine* later this year.

Armstrong Sidebar--What are risk factors for foot ulcerations?

What are the risk factors for developing diabetes-related foot ulcerations? Podiatrists at The University of Texas Health Science Center at San Antonio have determined that several health factors, once used to classify patients as "high risk" for ulcerations, really don't have anything to do with determining a patient's likelihood of getting foot sores. "Our study findings are controversial," said Dr. David Armstrong, assistant professor of podiatry. "Initially, they're likely to raise a lot of eyebrows."

Physicians have assumed, explained Dr. Armstrong, that a myriad of factors, including poor blood flow to the legs, kidney damage, vascular disease, vision problems, education level and marital status, placed a patient at higher risk for developing a diabetes-related foot ulcer. "These may be risk factors for not *healing* a sore," Dr. Armstrong said, "but they're not risk factors for *getting* one. Once people look at this logically, they'll realize our findings aren't so revolutionary.

"Once a patient has a sore, perhaps evaluating all those factors is of critical importance, but they're not as important in and of themselves for determining the risk of *getting* a sore," he added.

Dr. Armstrong suggests physicians look for five risk indicators: gender--men are at greater risk, poor glucose control, previous foot sores, foot deformity and lack of protective sensation.

"Hopefully, these findings will make initial evaluation of patients far easier for primary care providers--there are fewer things to look at for the patient without an ulcer," Dr. Armstrong explained.

The study, "Risk Factors for Diabetic Foot Ulceration: Practical Criteria for Screening," will be published in the *Archives of Internal Medicine* later this year. Drs. Lawrence Harkless, professor, and Lawrence Lavery, assistant professor, podiatrists in the department of orthopaedics, also were on the research team.

Contact: Joanne Shaw (210) 567-2570