Development and validation of an ankle brachial index risk model for the prediction of cardiovascular events

Abstract

Background The ankle brachial index (ABI) is related to risk of cardiovascular events independent of the Framingham risk score (FRS). The aim of this study was to develop and evaluate a risk model for cardiovascular events incorporating the ABI and FRS. Design An analysis of participant data from 18 cohorts in which 24,375 men and 20,377 women free of coronary heart disease had ABI measured and were followed up for events. Methods Subjects were divided into a development and internal validation dataset and an external validation dataset. Two models, comprising FRS and FRS + ABI, were fitted for the primary outcome of major coronary events. Results In predicting events in the external validation dataset, C-index for the FRS was 0.672 (95% CI 0.599 to 0.737) in men and 0.578 (95% CI 0.492 to 0.661) in women. The FRS + ABI led to a small increase in C-index in men to 0.685 (95% CI 0.612 to 0.749) and large increase in women to 0.690 (95% CI 0.605 to 0.764) with net reclassification improvement (NRI) of 4.3% (95% CI 0.0 to 7.6%, p = 0.050) and 9.6% (95% CI 6.1 to 16.4%, p < 0.001), respectively. Restricting the FRS + ABI model to those with FRS intermediate 10-year risk of 10 to 19% resulted in higher NRI of 15.9% (95% CI 6.1 to 20.6%, p < 0.001) in men and 23.3% (95% CI 13.8 to 62.5%, p = 0.002) in women. However, incorporating ABI in an improved newly fitted risk factor model had a nonsignificant effect: NRI 2.0% (95% CI 2.3 to 4.2%, p = 0.567) in men and 1.1% (95% CI 1.9 to 4.0%, p = 0.483) in women. Conclusions An ABI risk model may improve prediction especially in individuals at intermediate risk and when performance of the base risk factor model is modest.

Prognostic Value of the Ankle-Brachial Index in Patients Undergoing Drug-Eluting Stent Implantation

“…There were also significant differences in the cumulative event rate between the patients with an ABI of 0.9-1.056 vs. an ABI of ≥ 1.057 in this study. These results are in agreement with the findings of prior studies 5,[22][23][24] . Although an ABI of ≥ 0.9 assessed according to dichotomous categorization is usually classified as indicating 'no disease', many studies have shown an increase in risk proportional to a decrease in ABI, even among patients with an ABI of ≥ 0.9.…”

“…Hemodynamically significant arterial stenosis results in a resting ABI of 0.9, and this value is most often used to hemodynamically define PAD 4) . Many studies have also shown an ABI 0.9 to be an independent predictor of cardiovascular morbidity and mortality in various populations 21,22) . In the present study, there was a significant difference in the rate of cardiovascular events between the groups with the highest and middle tertiles of ABI.…”

The Association between Changes in Urinary Albumin-to-Creatinine Ratio and Risk of Abnormal Ankle-Brachial Index in a Community-Based Chinese Population

“…Using data from the Strong Heart Study 23) , they reported that the adjusted hazards ratio of ABI ＞1.4 was 1.77 (95%CI 1.48-2.13) for all-cause mortality and 2.08 (95%CI 1.49-2.94) for cardiovascular mortality. This association was confirmed by another cohort study [24][25][26] . It is suggested that high ABI could be related to poor arterial compressibility resulting from stiffness and calcification 26) .…”

“…This association was confirmed by another cohort study [24][25][26] . It is suggested that high ABI could be related to poor arterial compressibility resulting from stiffness and calcification 26) . Limited cross-sectional studies indicated that elevated urinary ACR was associated with peripheral artery disease defined by the presence of ABI ＜0.9 or ＞1.4 5,11) .…”

Comparison of ankle brachial pressure index to arterial doppler USG in the diagnosis of peripheral vascular disease in diabetes mellitus

“…Additionally, PAD causes significant long-term disability in diabetic patients. 1 The treatment of patients with PAD can therefore be expensive, owing to need for a variety of diagnostic tests, therapeutic procedures, and hospitalizations. 2 PAD can be clinically identified by intermittent claudication and/or absence of peripheral pulsations in the lower extremities.…”