Control/Tracking Number: 12-A-508-CCC
Current Date/Time: 7/15/2012 11:39:26 AM
THE SENSITIVITY, SPECIFICITY AND ACCURACY OF THE TOE-BRACHIAL INDEX FOR THE DIAGNOSIS OF PAD
Author Block M Matangi, D Armstrong, C Tobin, D Brouillard
BACKGROUND: The toe-brachial index is recommended for the diagnosis of peripheral arterial disease (PAD) in patients with an ankle-brachial index (ABI) of >1.30 and symptomatic patients with a normal ABI. We routinely perform the TBI on all patients and believe the TBI provides useful clinical information. The purpose of this study was to compare the TBI with the ABI which is the gold standard for the diagnosis of PAD.
METHODS: Our cardiology database was searched for all patients who had both the ABI and TBI measured. An abnormal ABI was <0.90 and an abnormal TBI was <0.70. A scattergram of ABI versus TBI was performed and the sensitivity, specificity, accuracy, negative predictive value (NPV), positive predictive value (PPV), positive likelihood ratio (+LR) and negative likelihood ratio (-LR) were calculated.
RESULTS: There were 5,192 lower limbs where both ABI and TBI were measured. The overall prevalence of PAD was 17.7%. The main results are seen in the image and Table below.
CONCLUSION: The TBI has a very high sensitivity, NPV and low -LR. A normal TBI almost excludes a diagnosis of PAD. The very low -LR indicates that a patient without PAD is 10 times more likely to have a normal TBI compared to a patient with PAD.
||ABI ≥ 0.90
||PPV = 49%
||NPV = 98%
|The +LR was 4.42 and the -LR was 0.09