In study A, 57 percent (39 out of 69) of patients with a diabetic foot ulcer had a percent area reduction greater than or equal to 50 percent by week four. Fifty-two percent (38 out of 73) of patients with diabetic foot ulcers in study B healed by 12 weeks. Five percent of diabetic foot ulcers in study A and 2 percent in study B healed at 12 weeks with a percent area reduction of less than 50 percent at four weeks.
Lavery and co-workers also studied the progression of the postoperative diabetic foot by evaluating the percent wound area reduction at one week and four weeks.18 The patients in this study had large, non-ischemic, diabetic foot wounds following partial amputations. The 16-week randomized clinical study of 129 patients compared outcomes of patients who had negative wound pressure therapy (NPWT) using the vacuum assisted closure (VAC, KCI) system in 77 patients versus moist wound therapy in 85 patients.
The results of the study revealed that the percent wound area reduction at one week was predictive of complete wound healing at 16 weeks.18 Wounds that had a 15 percent or greater percent wound area reduction at one week had a 68 percent chance of healing versus a 32 percent healing rate for wounds that did not reach a 15 percent wound area reduction.
Furthermore, the percent wound area reduction at four weeks was predictive of complete closure at 16 weeks.18 Wounds that had a percent wound area reduction of 60 percent or greater at four weeks had a 77 percent chance of healing versus 30 percent for those wounds that did not reach a 60 percent wound area reduction. Wounds treated with NPWT at one week had an 18.9 percent wound area reduction, which was associated with a 60 percent chance of healing. Wounds treated with moist wound therapy at one week had a 9.9 percent wound area reduction, which was associated with a 39 percent chance of healing.
Currently, the American Diabetic Association states that 8.3 percent of the current population has diabetes.19,20 This percentage includes 18.8 million people diagnosed with the disease and an estimated 7.0 million people who are undiagnosed.19,20 In 2007, complications from diabetes contributed to a total of 231,404 deaths.20 Complications such as diabetic foot ulcers are responsible for more hospitalizations than any other complication of diabetes. In 2006, surgeons performed approximately 65,700 non-traumatic lower-limb amputations in people with diabetes.19,20
Pathological conditions such as peripheral neuropathy, foot deformities and trauma predispose patients to diabetic foot ulcers. Limb loss is a significant risk in patients with diabetic foot ulcers, particularly if treatment has been delayed.21,22 When it comes to patients with diabetes and neuropathy, even if successful management results in healing of the foot ulcer, the recurrence rate is 66 percent and the amputation rate rises to 12 percent.22,23
It is also crucial to remember that proper offloading and debridement contribute significantly to the healing process.3 Additionally, if there is any presence of infection within a diabetic wound, one must provide primary treatment with appropriate antibiotics in order for proper wound healing to occur.
Overall, the review of the literature advocates that the advanced therapies that reign superior in diabetic wound healing are negative pressure wound therapy and bioengineered skin substitutes. Furthermore, it appears that the 50 percent reduction in ulcer area and four weeks of treatment protocol are indeed the magic numbers that predict the healing potential of a diabetic ulceration, and determine whether the treatment course remains unchanged or warrants adjunctive therapy.
Dr. Houston is a third-year resident at Yale New Haven Hospital in New Haven, Conn.