External validation of the DIAFORA system to predict lower-extremity amputations in a prospective Danish cohort

Abstract

Aim

A diabetes-related foot ulcer (DFU) is a major risk factor for lower-extremity amputation (LEA). To help clinicians predict the risk of LEA in people with DFU, the Diabetic Foot Risk Assessment (DIAFORA) system was developed but has never been externally validated.

Methods

In this study, 317 people presenting with a new DFU were included. At baseline, participants were grouped into three groups based on their DIAFORA score: low-risk (<15), medium-risk (15–25), and high-risk (>25). Participants were followed until healing, LEA, death, or at least 3 months. Discriminative accuracy was evaluated using sensitivity, specificity, likelihood ratios (LRs) and the area under the curve (AUC).

Results

All 317 participants completed at least 3 months of follow-up for a median duration of 146 days, during which 12.6% underwent minor amputation and 2.5% major amputation. People in the low- and medium-risk categories had major amputation rates of 0.9% and 2.1%, respectively, and negative LR of major LEA of 0.10 and 0.38, respectively, while the people in the high-risk category had an amputation rate of 25.0% and a positive LR of 12.9. The DIAFORA risk groups had a sensitivity of 75.0% and a specificity of 65.7%, with a corresponding AUC of 0.78 (95% CI 0.68–0.87) for the prediction of major LEA.

Conclusion

The DIAFORA score is a useful tool for risk stratification of people presenting with a newly occurred DFU, with the external validation presenting results similar to those presented in the original study. The DIAFORA score may guide clinicians towards more individualized DFU treatment regimens.