Validation and comparison of currently available stratification systems for patients with diabetes by risk of foot ulcer development

Aims/hypothesis: There are five systems to stratify the risk for the development of a diabetic foot ulcer (DFU). This study aimed to prospectively validate all of them in the same cohort of participants to allow their direct comparison. Methods: A retrospective cohort study was conducted on all patients with diabetes but without an active DFU attending our podiatry section (n=364) from January 2008 to December 2010. Participants' characteristics and all variables composing the stratification systems were assessed at baseline. Follow-up was performed for 1 year or until DFU occurred. Results: Participants had a mean age of 64 years; 99.7% had type 2 diabetes and 48.6% were male. Median follow-up was 12 months (1-12) during which 33 subjects (9.1%) developed a DFU. Age, diabetes duration, foot deformity, peripheral vascular disease, diabetic peripheral neuropathy, previous DFU, and previous lower extremity amputation were associated with DFU occurrence. All systems presented greater DFU occurrence frequency as the risk group was higher (chi(2), P<0.001) and showed good diagnostic accuracy values, especially negative predictive value (>= 95%) and area under the receiver operating curve (>= 0.73). The lowest performance concerned positive predictive value (<= 29.5%). Conclusions/interpretation: All the currently available stratification systems show high accuracy to detect which patients will develop a DFU with no significant differences among them. Therefore, for diabetic foot screening and resource allocation, it would be desirable to have a single unified system, combining the available systems, prospectively validated in a multicenter context and testing the inclusion of novel predictive variables' pertinence.