Ankle Brachial Index vs Transcutaneous Partial Pressure of Oxygen for Predicting Healing of Diabetic Foot Ulcers with Peripheral Arterial Disease: a Comparative Study

Foot ulcer is a common complication of diabetes mellitus. The co-existence of peripheral arterial disease (PAD) increases the risk of non-healing of the ulcer. Ankle brachial index (ABI) and transcutaneous partial pressure of oxygen (TcPO₂) are two tests used to assess the vascularity of the foot, using two different parameters. This study was done to compare the sensitivity, specificity and diagnostic accuracy of ABI and TcPO₂ and to find out which of these is a better predictor of healing in diabetic foot ulcers in patients without palpable foot pulses. The hospital-based longitudinal study was done from March 2016 to March 2018 among 121 adult patients diagnosed with diabetic foot ulcer without palpable peripheral pulses who fit the inclusion and exclusion criteria. Vascularity of the foot in these patients was assessed using ABI and TcPO₂. The participants were followed up for 3 months, and the healing status was recorded. The mean (SD) age of patients was 64.99 (10.03) years. Out of 121 patients, 89 were men and 32 were women. The mean ABI in healed and non-healed group were significantly different (P value < 0.001). TcPO₂ also showed significant difference in healed and non-healed groups (P value < 0.001). The values of 0.65 in receiver operating characteristic (ROC) curve showed optimal sensitivity (86.1%) and specificity (75.5%) for ABI. ROC curve with a TcPO₂ cut-off value of 27.5 mmHg had optimal sensitivity (84.7%) and specificity (81.6%). Although sensitivity of TcPO2 and ABI is comparable (84.7% v 86.1%), specificity and diagnostic accuracy are better for TcPO₂.