MIAMI BEACH – The extent of vascular disease, not the presence of diabetes or the cause of the ulceration, should drive the decision to intervene in a patient with a "diabetic foot," according to Dr. Joshua Beckman.
"When do I intervene on a diabetic foot? When I intervene on all feet: when there’s inadequate blood flow to heal the lesion," he said at the International Symposium on Endovascular Therapy 2013.
When lesions are detected in diabetic patients with PAD, assess for ankle pressures and determine ankle brachial index regardless of whether the lesion is neuropathic, he advised, explaining that, "even if you have a neuropathic initiation for your ulcer, if you have a low perfusion pressure, particularly under 50 mmHg, you’re not going to heal that lesion no matter how it was started."
"I always assess patients, whether I think the lesion is a neuropathic one or not, for the ankle pressures and do ankle brachial index and, assuming it’s low, I refer for revascularization based on the same criteria I would everybody else," said Dr. Beckman of Harvard Medical School, Boston.
That said, up to one-third of patients with diabetes have peripheral artery disease, and its presence is an independent predictor of adverse outcomes. "In fact, the combination of PAD and diabetes represents the group of people in the United States that has the most amputations, and their risk may be 20-fold that of people without both PAD and diabetes," he noted.
Indeed, the risk of amputation is much greater in diabetic patients, regardless of the care they receive, Dr. Beckman said, citing a study of 136 lower-extremity angiograms in patients with PAD. The odds ratios for amputation and death at 4.5 years’ follow-up were 5.4 for those with diabetes and 3.1 for those without diabetes (Diabetes Care 2001;24:1433-7).
Additionally, in a study of 1,244 men with claudication, the risk of ischemic ulceration was 4-fold higher in diabetic patients than in nondiabetic patients. Ankle brachial indices ranged from 0.9 to 0.1, and there was no point at which a diabetic patient was not worse off than a nondiabetic patient, he said. The risk in a diabetic patient with an ankle brachial index of 0.9 was equal to the risk in a nondiabetic patient with an ankle brachial index of 0.1 (J. Vasc. Surg. 2001;34:962-70).
Diabetic patients also can have a number of other initiators of diabetic foot ulceration, including neuropathy, bone deformity, callus, penetrating injury, and ill-fitting shoes. In combination, these factors can be especially problematic, he said.
Also, the extensor muscle abnormality that can result from motor neuropathy can change foot morphology, thereby increasing pressure on areas such as the ball of the foot, where ulcers are common.
Furthermore, a patient with neuropathy can walk around for a long time without recognizing a problem that an individual with normal nerve function wouldn’t tolerate. "A diabetic patient can have a bad shoe that rubs all day and not appreciate it," Dr. Beckman said.
With PAD, there are a "whole host of issues we never deal with in the nondiabetic patient that really accelerate the pathway toward ischemic ulceration and critical limb ischemia," he said. "Diabetes is a risk multiplier. It makes things worse, and it’s far more involved in the initiation [of ulceration] than in the decision whether to fix somebody."
Further underscoring the importance of such follow-up is a study of 533 diabetic patients hospitalized for critical limb ischemia. Nearly 50% of them developed critical limb ischemia in the contralateral limb at 6-year follow-up (Diabetes Res. Clin. Prac. 2007;77:445-50).
"So this is a group of people who need not only exquisite care, but exquisite surveillance, because it is very likely that, over time, they will come back to your office with the same problem in the other foot. I’m not recommending intervention or surgery in the asymptomatic foot, but I am suggesting you should probably never let them go, and have routine follow-ups where you look at their feet every time," he said.
Dr. Beckman reported having no disclosures relevant to his talk.