Transcutaneous oxygen pressure as a predictor for short-term survival in patients with type 2 diabetes and foot ulcers: a comparison with ankle–brachial index and toe blood pressure

Abstract

Aims: Ankle–brachial index (ABI) is the most commonly used test when diagnosing peripheral vascular disease and is considered a marker for cardiovascular risk. Transcutaneous oxygen pressure (TcPO2), a test associated with microvascular function, has in several studies shown better correlation with diabetic foot ulcer (DFU) healing. Whether a low TcPO2 could be a marker for mortality in the high-risk population of DFU patients has not been evaluated before. The aim of this study was to evaluate the predictive value of TcPO2 in comparison with ABI and toe blood pressure (TBP) on 1-year mortality in type 2 diabetes patients with DFU. Methods: Type 2 diabetes patients aged ≤ 90 years, with one DFU who attended our multidisciplinary DFU-unit during year 2013–2015 and were screened with TcPO2, ABI and TBP were retrospectively evaluated. One-year mortality was assessed from the national death register in Sweden. Results: A total of 236 patients (30% women) with a median age of 76 (69–82) years were evaluated in this study. Within 1 year, 14.8% of the patients died. TcPO2 < 25 mmHg was associated with a higher 1-year mortality compared with TcPO2 ≥ 25 mmHg (27.7 vs. 11.6%, p = 0.003). TBP and ABI did not significantly influence 1-year mortality. In a Cox regression analysis adjusted for confounders, TcPO2 was independently predicting 1-year mortality with a hazard ratio for TcPO2 < 25 mmHg of 2.8 (95% CI 1.34–5.91, p = 0.006). Conclusions: This study indicates that a low TcPO2 is an independent prognostic marker for 1-year mortality among patients with type 2 diabetes and DFU.