Thermography‐Assisted Grading in Wagner Classification: A New Approach for Diabetic Foot Assessment. A Cross‐Sectional Study

BACKGROUND: Diabetic foot is a serious complication of diabetes mellitus that generates lifelong consequences on the health and quality of life of affected patients. One of the first grading systems developed for diabetic foot was the Wagner classification system. Despite its prolonged use in the medical field, accurate clinical assessment requires an experienced evaluator to minimize errors and bias. Using infrared thermography, a technology that quantitatively measures temperature changes in areas of interest related to altered vascular flow derived from inflammatory processes, could diminish the subjective bias associated with clinical evaluation. OBJECTIVE: To determine the thermographic pattern of the different grades of the Wagner classification system for diabetic foot. METHODS: We evaluated thermographic images of 66 patients diagnosed with diabetic foot. Clinical data and infrared thermographic images were acquired at the moment of evaluation. Temperature differences (ΔT) between the first toe of the affected limb and the contralateral unaffected first toe were recorded and analyzed with computer software. The thermographic patterns were then compared with the Wagner classification system grades. RESULTS: A positive ΔT was observed in 36 patients in the first three Wagner grades: Wagner 0, ΔT 0.71°C ± 0.43; Wagner 1, ΔT 1.17°C ± 1.88; and Wagner 2, ΔT 2.18°C ± 2.38. Thirty patients presented negative ΔT from the third grade onward: Wagner 3, ΔT -2.66°C ± 1.14; Wagner 4, ΔT -5.92°C ± 1.75, and Wagner 5, ΔT -6.92°C ± 1.28. Then, we separate the cohort into two groups: patients who required amputation and those who required conservative management. A threshold in the ΔT value of -2.6 correctly predicted the outcome in more than 95% of patients. CONCLUSIONS: These results suggest a potential application for thermography as an adjunctive tool in wound clinics, enabling the accurate evaluation of diabetic foot ulcers and as a predictor of patients' outcomes. TRIAL REGISTRATION: Registry: 08-23 by the Hospital Regional de Alta Especialidad "Dr. Ignacio Morones Prieto" Research Ethics Committee (CONBIOÉTICA-24-CEI-001-20160427).