Development and validation of the Diabetic Foot Ulcer Scale-short form (DFS-SF)

Background: The Diabetic Foot Ulcer Scale (DFS) provides comprehensive measurement of the impact of diabetic foot ulcers on patients' QOL through self-administration of 64 items comprising 15 subscales. Objective: To develop and evaluate a short form of the DFS (DFS-SF) to reduce patient burden and the number of outcome measures, and to improve sensitivity to change in clinical condition. Methods: The DFS-SF was created through the analysis of data from a double-blind, placebo-controlled, randomised trial of the efficacy and safety of becaplermin (recombinant human platelet-derived growth factor BB) in the treatment of chronic, full-thickness, neuropathic, diabetic foot ulcers. Using these data, items demonstrating poor psychometric properties were eliminated. Exploratory factor analyses were then conducted to develop a new, more parsimonious scaling algorithm that optimised the internal consistency of the new subscales. Finally, data from two additional clinical trials were used to assess replicability of the DFS-SF subscale structure. Results: The DFS-SF contains a total of 29 items comprising six subscales. The results of both confirmatory and exploratory factor analyses provided support for the scaling algorithm. The DFS-SF subscales showed good internal consistency, reliability and construct validity, and demonstrated sensitivity to ulcer healing. Conclusions: The results of this investigation indicate that the DFS-SF has good psychometric properties and replicability.