Skin hydration level cutoff value to predict wound healing potential in diabetic foot ulcers

Transcutaneous oxygen pressure (TcPO₂) is a reliable predictor of wound healing in diabetes patients; however, measurements are cumbersome. Previously, we demonstrated that skin hydration in the feet of patients with diabetic foot ulcers (DFU) is influenced by microcirculation rather than peripheral nerve function. Furthermore, skin hydration level before recanalization can predict wound healing better than TcPO₂. This study investigated the skin hydration level cutoff value to predict DFU healing.

We retrospectively enrolled 834 patients with DFU. Wound healing outcomes were graded as healed without amputation or with minor/major amputation. Receiver operating characteristic analysis was used to evaluate the ability of skin hydration to predict wound healing outcomes and determine the optimal cutoff value for subsequent analyses.

Average skin hydration values in the healed without and with amputation groups were 25.0 ± 7.4 arbitrary units (a.u.) and 17.5 ± 5.7 a.u., respectively (P < 0.001). The healing rate without amputation increased with skin hydration. A skin hydration value ≥ 21 a.u. significantly lowered the incidence of amputation. The cutoff value was 21 a.u. [(Youden's index, sensitivity, specificity, P-value) = (1.6, 92, 69.6, P < 0.001)].

A minimal skin hydration value of 21 a.u. is required for diabetic wound healing.