Transitioning To Advanced Therapies For DFUs: Are Four Weeks And 50 Percent The Magic Numbers?

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What One Study Reveals About A Bioengineered Skin Substitute And The Rate Of Healing Of Diabetic Foot Ulcers

In a prospective, randomized, multicenter study, Veves and colleagues analyzed 208 patients with diabetes who had full-thickness neuropathic ulcers, and observed the healing rates of diabetic neuropathic ulcers that were treated with Apligraf (Organogenesis) versus diabetic neuropathic ulcers treated with saline-moistened gauze.10 At baseline, the two groups were similar in regard to demographics, the type and duration of diabetes, and ulcer size and duration. The Apligraf group was comprised of 112 patients and there were 96 patients in the control group, which utilized saline-moistened gauze as treatment. Both groups received periodic debridement and offloading in addition to the respective treatment for their group.

The researchers analyzed 162 patients at the end of the study. The rate of healing was higher among those who had Apligraf applied every week than those who received saline moistened gauze. At the 12-week follow-up visit, 63 (56 percent) Apligraf-treated patients were completely healed in comparison to 36 patients (38 percent) treated with saline-moistened gauze. The average time to complete closure was 65 days for Apligraf, significantly lower than the 90 days researchers observed in the saline-moistened gauze group.

The rate of adverse reactions was similar between the two groups with the exception of osteomyelitis (3 percent in the Apligraf group versus 10 percent in the control group) and lower-limb amputations (6 percent versus 16 percent), both of which were less frequent in the Apligraf group. The study also noted the improvement in maceration, exudates and eschar in the Apligraf group from week 0 to week 12. Physicians should consider Apligraf for the management of diabetic foot ulcers that are resistant to the currently available standard of care.

Chanel Houston, DPM, Samirah Mohammed, DPM, and Peter A. Blume, DPM, FACFAS

   Various authors have reported on treatment options for diabetic foot ulcers. These modalities include advanced moist wound therapy; periodic wound debridement to remove bacterial biofilm and hyperkeratosis; bioengineered tissue or skin substitutes; growth factors; electric stimulation; and negative pressure wound therapy (NPWT).6-14 Many factors can influence the outcome of treatment. These factors include the nature of the ulcer, the presence of infection, patient adherence, appropriate offloading and the mechanisms of action of the therapy. Even with all appropriate measures, some wounds still fail to heal.

What The Literature Reveals About The Prognostic Value Of The Percentage Of Wound Area Reduction At Four Weeks

Due to the complexity of diabetic foot ulcers and the difficulty it takes to heal them, some studies have reported that an area reduction greater than or equal to 50 percent at four weeks of treatment is a good prognostic indicator about an ulcer’s ability to heal at 12 or 20 weeks.

   In particular, Sheehan and his colleagues published a study describing that diabetic foot wounds that do not heal by at least 50 percent in the first four weeks of treatment have less than a 10 percent chance of closing by week 12.15 They studied the healing rate of 203 patients with chronic diabetic foot ulcers receiving standard wound care therapies. They also looked at the healing ability of ulcers as a direct correlation with their percent area of reduction.

   This large prospective study from 2003 has been widely cited in the recent literature because it revealed that patients who did not reduce their wound area by approximately 50 percent at the four-week average had a very low probability of healing. The study authors further concluded that physicians need to re-evaluate diabetic foot wounds on a regular basis so they can redirect treatment if a wound is not healing as expected.

   Boulton and colleagues also noted that the failure to reduce the size of an ulcer after four weeks, even with appropriate debridement and pressure reduction, should prompt consideration of adjunctive therapy. They noted this in 2004 when they developed a clinical practice article for neuropathic diabetic foot ulcers, which was published in The New England Journal of Medicine.16 The authors reviewed literature about the general management of diabetic foot ulcers and treatment options such as infection management, offloading, routine debridement, glycemic control, and the use of growth factors and tissue-engineered skin. Boulton and co-authors recommend the use of adjunctive treatment options such as tissue-engineered skin when a patient has not had a 50 percent decrease in wound size at four weeks.

   Snyder and colleagues did a post-hoc analysis about percent area reduction and an ulcer’s ability to heal at four weeks in 2010.17 The study looked at two previously conducted studies consisting of patients with type 1 diabetes and patients with type 2 diabetes. Both groups (study A and study B) received debridement, a saline-moistened gauze dressing covered with dry gauze (wet to dry) and adhesive fixation sheets. Both groups also utilized therapeutic footwear and received offloading instructions.

   For study A, 133 patients had a pre-trial standard of care treatment for two weeks and had a full thickness DFU on the heel or plantar foot greater than 1 cm2. The ulcer was essentially the same size during the two-week pre-trial period. There were 117 patients in study B but they did not receive standard of care treatment prior to the study.

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