The Choice of Diabetic Foot Ulcer Classification: Discussion

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The Choice of Diabetic Foot Ulcer Classification: Discussion
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In this study we investigated the Van Acker/Peter classification system, a new diabetic foot ulcer classification. We compared its performance with that of the existing clinically validated Wagner classification.[12,13] The classifications were assessed by evaluating clinical outcome, e.g. healing with or without amputation and duration of healing.

Our results show that in the VA/P classification the prevalence of amputation increases significantly with increasing extent of grade of infection and is related to vascular origin. Also, in the Wagner classification, a strong positive relationship exists between prevalence of amputation and Wagner scores.[12] According to amputation rate, Wagner class 3 seems to be a heterogeneous group. In addition, both VA/P and Wagner classifications show a similar association with duration of healing time, although the best linear trend in healing times was seen in the Wagner classification.

The VA/P classification is based upon the Texas Classification and takes into account not only clinical features, such as depth and grade of infection (horizontal axis), but also the physiopathological background (vertical axis), where ischemic components play a role.

The Texas Diabetic Wound Classification is the first combined bidimensional classification published in 1996 by Lavery, Armstrong, and Harkless. Harkless described in an earlier publication a combined classification based on the Wagner stages (0-5).[14,15] He created subclasses depending on the presence of ischemia. The ischemic or B-forms were described as presenting a weaker prognosis than the nonischemic A-forms. The actual classification by Lavery, Armstrong, and Harkless is based on three essential questions: depth of the ulcer, infection, and ischemia.

The Meggit/Wagner classification is probably the best known and the most frequently used. Nevertheless, it is described as very simple and, therefore, often considered to be inconveniently inaccurate. Sims, et al., noted that the scheme provides insufficient levels to discriminate between wounds that may benefit from nonsurgical rather than surgical management. The grading system was adapted in 1988 by Calhoun, et al., in order to combine medical and surgical elements of therapy to monitor the treatment of diabetic foot infection.[16]

Both Wagner and horizontal axis of the VA/P classifications correspond well regarding the prediction of healing with amputation. This was to be expected, as both are based mainly on the clinical picture. The vertical axis of the VA/P also is associated with the chance of healing with amputation. As no correlation exists between the horizontal axis and the vertical axis of the VA/P, these characteristics can be considered as complementary to one another and, therefore, may provide additional information.

However, because the probability of amputation in Wagner 1 and 2 is low in all pathological classes, and in Wagner 4 all ulcers are prevalent in the vascular (DE) class only, additional information is useful in the Wagner class 3 in particular. According to the VA/P classification, Wagner 3 appears to be a heterogeneous subgroup. Forty-two of 43 ulcers in Wagner 3 are classified as VA/P class 3 or 4, belonging to all three pathological classes. Likewise, of the 13 ulcers in Wagner 3 that healed with amputation, 12 were classified as VA/P class 4, with amputation rates rising from 30 to 50 percent over the pathological VA/P levels. Thus, within Wagner 3 the presence of osteomyelitis (VA/P class 4) is the determining factor related to healing with amputation, with vascular pathology (VA/P class DE) as a secondary risk factor. Unlike Wagner 3, Wagner 4 is a homogeneous subgroup regarding pathological background. This is not surprising, as gangrene is restricted to underlying vascular pathology. However, the risk of amputation is unrelated to the extent of the ulceration.

According to the VA/P classification, 97 ulcers (38%) were of vascular origin. However, of those, only 26 percent were categorized in the Wagner 4 group, whereas 74 percent were assigned to Wagner classes 1 through 3. By incorporating the physiopathological axis, the VA/P classification gives more detailed information concerning the ischemic origin of ulcers. Lavery, Armstrong, and Harkless already mentioned that ischemic ulcers present a weaker prognosis than nonischemic ulcers.[14]

Like previous studies,[17] our study demonstrates the long duration of healing of diabetic foot ulcers. Our study also confirms the results from the Texas group[14,15] that ischemic wounds (VA/P class DE) have a longer duration of healing compared with neuropathic wounds without bone deformities (VA/P class A). However, no differences were found between neuropathic wounds with (class BC) or without (class A) bone deformities. These findings warrant our approach for taking into account the physiopathological background in the classification system.

In conclusion, for daily clinical practice a simple, though accurate, classification system is necessary in order to give adequate therapy and to predict probable outcome. In his editorial, Levin suggested that the American Diabetes Association would provide a consensus statement on classification of diabetic foot ulcers. In general, the new ulcer classification VA/P, which takes into account the underlying pathology of the ulcers, gives more detailed information than the Wagner classification. In the intermediate category (e.g., Wagner 3) in which the risk of amputation is related to size/depth and the physiopathological characteristics of the ulcer, the new VA/P classification seems preferable. Furthermore, the VA/P classification characterized by more detailed information may also be useful in well-organized multidisciplinary diabetic foot clinics and in multicenter research. However, because of its simplicity, the Wagner classification remains a perfectly usable instrument in everyday clinical practice (e.g., in primary health care).

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