Use of the ankle-brachial index combined with the percentage of mean arterial pressure at the ankle to improve prediction of all-cause mortality in type 2 diabetes mellitus: an observational study

BACKGROUND: Peripheral artery disease (PAD) in the lower extremities is a common complication of type 2 diabetes and has been shown to be associated with mortality. The ankle-brachial index (ABI) is a simple noninvasive method to screen PAD, but this method has limited sensitivity. We hypothesized that using the percentage of mean arterial pressure (%MAP) in combination with the ABI would improve the prediction of mortality. METHODS: We retrospectively collected data from patients with type 2 diabetes who had undergone ABI and %MAP measurements at our hospital. We separated the cohort into four groups according to their ABI and %MAP values, and we examined whether these indices were associated with mortality. RESULTS: A total of 5569 patients (mean age, 65 ± 11 years) were enrolled. During the follow-up period (median, 22.9 months), 266 (4.8%) of the enrolled patients died. The combination of ABI and %MAP was significantly more effective than ABI alone for predicting mortality (C index of 0.62, 95% confidence interval [CI] of 0.57 to 0.65 vs. C index of 0.57, 95% CI of 0.53 to 0.62; P = 0.038). In multivariate analysis (with a reference group defined by ABI > 0.90 and %MAP ≤ 45%), the highest risk of mortality was seen in patients with ABI ≤ 0.90 and %MAP > 45% (hazard ratio = 2.045 [95% CI 1.420, 2.945], P < 0.001). CONCLUSIONS: The use of %MAP alongside ABI appears to significantly improve the prediction of all-cause mortality in patients with type 2 diabetes.