Understanding The Effects Of PAD On The Diabetic Foot
The presence of peripheral arterial disease (PAD) in patients with diabetes can result in devastating complications. Multidisciplinary care is critical for these patients. Accordingly, these authors review the current literature and offer pertinent diagnostic insights and keys to effective treatment.
With diabetes affecting 5 to 10 percent of the U.S. population, effective management of diabetes-related complications is imperative both socially and fiscally.
Foot ulcers develop in approximately 15 percent of patients with diabetes with an annual incidence of foot ulceration of slightly more than 2 percent among all people with diabetes and between 5 and 7.5 percent among people with diabetes and peripheral neuropathy.1 Singh and colleagues have estimated that there is a 25 percent lifetime risk for someone with diabetes to develop a foot ulceration during his or her lifetime.2
Foot ulcers are a harbinger of amputation and they precede 85 percent of lower limb amputations.3 This statistic highlights the importance of ulcer prevention and appropriate management of foot ulcers that are already present.
There are a number of contributing factors that interact and as they aggregate, they may lead to a foot ulceration.4 Reiber and colleagues established a causal pathway to foot ulceration in people with diabetes. Based on an analysis of 146 patients with foot ulcers, these researchers found that the triad of peripheral neuropathy, trauma and deformity were present in almost two-thirds of the patients with foot ulcers.5
However, this study occurred in an outpatient diabetic foot clinic and may have excluded those patients admitted to the hospital or those with limb ischemia requiring surgical intervention. Therefore, the study may have underestimated the level of infection and peripheral arterial disease (PAD) that others have reported.6
The prevalence of PAD in people with diabetic foot ulcers ranges wildly from 10 to 60 percent.6 This large variation may be the result of using different criteria for defining PAD among different centers.
A Closer Look At The Literature On PAD
The European Study Group on Diabetes and the Lower Extremity (Eurodiale), which is a collaborative network of 14 European centers, conducted a large multicenter study to obtain data on clinical outcomes in patients presenting with a foot ulcer.7 This multidisciplinary group initiated a prospective data collection study for 1,229 consecutive patients presenting with a new foot ulcer. Peripheral arterial disease was present in 49 percent of patients but the incidence varied from 22 to 73 percent among the different participating centers.
This variation may be related to the differences in the prevalence of PAD but it more likely highlights the differences in the criteria used to define PAD. In patients without diabetes, the ankle brachial index (ABI) is the method of choice to screen for PAD. However, given the reduced compliance of blood vessels in diabetes secondary to arterial calcification, the pressures may not be accurate and the results may be misleading.
The researchers also found that the presence of PAD is a strong predictor of a non-healing foot ulcer.7 In addition, patients with diabetes had more severe disease in the distal arteries in comparison to those without diabetes. The study also found a relatively high prevalence of infection with 58 percent of all ulcers infected at initial presentation.