Pie diabetico...

In diabetic foot ulcers, use 50% rule to gauge need for advanced therapies

By: BRUCE JANCIN, Dermatology News Digital Network

VANCOUVER – When diabetic foot ulcer healing has stalled despite 4 weeks of optimal standard therapy, it's time to seriously consider resorting to advanced therapies, according to Dr. Afsaneh Alavi of the University of Toronto.

Advanced therapy options include negative pressure wound therapy, hyperbaric oxygen, artificial skin substitutes, growth factors, collagen-based dressings, and electromagnetic therapy.

"You hear a lot about advanced therapy for diabetic foot ulcers. It's expensive. But it can be cost-effective if used properly. It's our duty to see who is the best person to receive this therapy," she said at the World Congress of Dermatology.

A useful rule of thumb, the dermatologist added, is that if a healable ulcer isn't 50% smaller at week 4 despite optimal care, it's time to consider moving on to advanced therapies. As was shown in a well-conducted, 203-patient, randomized, prospective controlled clinical trial, a wound that hasn't met that threshold is unlikely to be healed at 12 weeks (Diabetes Care. 2003 Jun;26(6):1879-82). 

Two caveats: advanced therapy is appropriate only for healable diabetic foot ulcers, meaning those in patients with adequate peripheral circulation as defined by measurements of transcutaneous oxygen pressure, toe pressure brachial index, and Doppler studies.

"Eighty percent of diabetic patients have noncompressible arteries and therefore the ankle brachial index is not an accurate test to evaluate their circulation," according to Dr. Avali.

The other caveat regarding advanced therapy is that appropriate candidates should have a wound edge that's sharp, not migrating, she continued. 

The 4-week cutoff for seeing substantial progress in wound healing with standard therapy before turning to advanced therapies is based in part upon an influential study of 2,517 patients with diabetic neuropathic foot ulcers who received one of three advanced biological therapies. On average, patients started advanced biological therapy within 28 days following their first visit to a specialized wound clinic. Prolonged time to initiation of advanced treatment was associated with significantly longer time to healing (Arch Dermatol. 2010 Aug;146(8):857-62).

While thinking about local wound care in a patient with a diabetic foot ulcer, Dr. Avali said it's also important to take a step back and make sure hypertension and other conventional cardiovascular risk factors are well controlled and also to take a close look at the HbA1c. In a study of 183 patients with diabetic wounds treated at a specialized academic wound center, for every 1.0% increase in HbA1c above the mean level of 8.0%, the wound-area healing rate was reduced by 0.028 cm² per day. The implication is that HbA1c may be a key biomarker that's useful in predicting wound-healing rate in patients with diabetic ulcers (J. Invest Dermatol. 2011 Oct;131(10):2121-7). 

She reported serving as a consultant to Acelity and Smith & Nephew.

Benjamin Hidalgo-Matlock

Skin Care Physicians of Costa Rica

4000-1054

2208-8206

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