Validation of Wagner's Classification: A Literature Review
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P ractitioners attempt to provide care diligently, honestly, and sincerely. Clinical decision-making is an important tool used during treatment. Keenan and Redmond1 refer to the evaluation of evidence as one key factor that governs clinical decision-making. To ensure high quality care, Baxter and Baxter2 instruct practitioners to base their practice on sound clinical evidence. Redmond et al3 extends the concept because podiatrists rely on quantitative measurements when evaluating clinical research; these measurements must be accurate, reliable, and valid. Clinimetrics, the development and evaluation of measurements,4 may be applied to wound assessment tools such as diabetic foot ulcer classification systems.
Mulder5 acknowledges the existence of national guidelines for the treatment of chronic wounds. The Agency for Health Care Policy and Research6 and the National Pressure Ulcer Advisory Panel provide these practice guidelines.7 Zulkowski et al8 report that these guidelines are not designed to direct assessment of foot ulcers. The International Working Group on the Diabetic Foot agreed on 43 standard definitions for treating diabetic feet.9 However, a classification system for diabetic foot ulcers was not included because no one has documented having enough clinical experience with one system to validate or endorse it.10 Although many diabetic foot ulcer classifications are available, few have been clinically tested.
The first classification systems developed and accepted by clinicians were Meggitt's11 and Wagner's.12,13 The Wagner system is taught in podiatry colleges in the United States. The Wagner system is a source of questions used on the American College of Foot and Ankle Orthopedics and Medicine Board examination and has been introduced as evidence in United States' court proceedings.14
The purpose of this review is to present the Wagner dysvascular foot classification system, discuss its clinimetric properties, and examine existing validation literature of the Wagner and other diabetic classification systems.
Of the many diabetic wound classification systems available today, the Meggitt-Wagner Classification is the one most often cited. This system was first described by Meggitt11 and subsequently universalized by Wagner.13 The natural history of dysvascular foot breakdown is divided into six grades ranging from Grade Zero to Grade Five. For comparison purposes, both classification systems are presented in Figure 1. The Wagner system is similar to an ordinal scale denoting ranked order, allowing for nonparametric data analysis.15,16 Grade is determined based on depth of the skin lesion and the presence or absence of infection and gangrene.13,17
Both Meggitt's11 and Wagner's13 systems allow for bidirectional progression from Grade Zero to Grade Four and regression from Grade Four to Grade Zero. The property of bidirectionality is not generally accepted as a positive attribute to a classification system. One reason is that many third-party reimbursement plans are tied to a particular wound description or class. However, the original intent of Meggitt's11 and Wagner's13 was to allow for descriptionof the dysvascular foot over a period of time pre- and postsurgery and for nonsurgical interventions.11,13 Wagner's classification system is a visual one, implemented without the aid of an objective precision device like a ruler, grid, or measuring tape. Subjective in nature, it may be considered a noncontact measurement system. Jeffcoate et al18 considers this subjectivity a major disadvantage of the system. Initially, this subjectivity may present reliability concerns.
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