Toe–brachial index could help predict cardiovascular risk in patients with type 2 diabetes
medwireNews: Study results suggest that the toe–brachial index (TBI) is inversely associated with cardiovascular risk among patients with type 2 diabetes, and could help improve the prognostic ability of traditional prediction models.
These findings provide “support for the use of TBI as a tool refining risk prediction in type 2 diabetes,” say Emilie Zobel (Steno Diabetes Center, Copenhagen, Denmark) and study co-authors.
In an analysis of 200 patients with type 2 diabetes, microalbuminuria, and no clinical features of coronary artery disease, the team found that 40 participants experienced the composite endpoint of cardiovascular mortality, non-fatal myocardial infarction, stroke, ischemic cardiovascular disease (CVD), and heart failure over a median 6.1 years of follow-up.
Patients with lower TBI had a significantly higher risk for both the combined cardiovascular endpoint and all-cause mortality, with corresponding hazard ratios of 1.50 and 1.37 after adjustment for traditional cardiovascular risk factors including gender, age, blood pressure, and smoking status.
The inverse association between TBI and the combined cardiovascular endpoint remained significant following further adjustment for N-terminal pro-brain natriuretic peptide (NT-proBNP) level and coronary artery calcification score (HR=1.36).
And adding TBI to a prediction model based on traditional CVD risk factors significantly improved the model’s ability to predict the composite cardiovascular endpoint, with an improvement in the area under the receiver operating characteristic curve (AUC) value from 0.743 to 0.806.
The addition of TBI also improved the model’s predictive ability for all-cause mortality, but the improvement in AUC was not significant.
“Our findings of the added predictive value on top of traditional risk factors for both CVD and all-cause mortality highlight the great potential impact of implementing TBI measurement in type 2 diabetes in the clinical setting,” write Zobel and colleagues in Diabetologia.
“Identifying individuals with the highest risk can enhance guidance of intensive management of vascular risk factors, including tighter goal setting for blood pressure, [low-density lipoprotein]-cholesterol and other cardiovascular risk factors,” they continue.
The researchers also found that participants with a lower ankle–brachial index (ABI) had a significantly higher risk for the combined cardiovascular endpoint and all-cause mortality after adjustment for traditional cardiovascular risk factors (HR=1.44 and 1.39, respectively), but not after further adjustment for NT-proBNP and coronary artery calcification.
Adding ABI to the prediction model based on traditional risk factors did not significantly improve its ability to predict the composite cardiovascular endpoint or all-cause mortality.
“ABI has not been broadly implemented in daily practice for risk assessment in type 2 diabetes,” say the authors, noting that “ABI often is incorrectly normal because of vessel stiffness in diabetes.”
And they add: “The vessels in the toe are less susceptible to medial calcification, therefore TBI may be more reliable [than ABI] for risk assessment in diabetes.”
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