Validation of a diabetic wound classification system: The contribution of depth, infection, and ischemia to risk of amputation

OBJECTIVE - To validate a wound classification instrument that includes assessment of depth, infection, and ischemia based on the eventual outcome of the wound. RESEARCH DESIGN AND METHODS - We evaluated the medical records of 360 diabetic patients presenting for care of foot wounds at a multidisciplinary tertiary care foot clinic. As per protocol, all patients had a standardized evaluation to assess wound depth, sensory neuropathy, vascular insufficiency, and infection. Patients were assessed at 6 months after their initial evaluation to see whether an amputation had been performed. RESULTS - There was a significant overall trend toward increased prevalence of amputations as wounds increased in both depth (χ²(trend) = 143.1, P < 0.001) and stage (χ²(trend) = 91.0, P < 0.001). This was true for every subcategory as well with the exception of noninfected, nonischemic ulcers. There were no amputations performed within this stage during the follow-up period. Patients were more than 11 times more likely to receive a midfoot or higher level amputation if their wound probed to bone (18.3 vs. 2.0%, P < 0.001, χ² = 31.5, odds ratio (OR) = 11.1, CI = 4.0-30.3). Patients with infection and ischemia were nearly 90 times more likely to receive a midfoot or higher amputation compared with patients in less advanced wound stages (76.5 vs. 3.5%. P < 0.001, χ² = 133.5, OR = 89.6, CI = 25-316). CONCLUSIONS - Outcomes deteriorated with increasing grade and stage of wounds when measured using the University of Texas Wound Classification System.