Abstract 31: Toe Brachial Index (TBI) is more sensitive than Ankle brachial Index (ABI) in detecting peripheral arterial disease in persons with type 2 diabetes

Introduction: Ankle Brachial Index (ABI), a useful tool in diagnosingperipheral arterial disease (PAD), maygive falsely high values in sclerosed & calcified arteries. Toe Brachial Index (TBI) offers an alternative approach here, as digital arteries are unaffected by atherosclerotic changes and medial calcification. Aim: To find out the sensitivity and specificity of ABI and TBI in diagnosing PAD in T2D compared to CT angiography (CTA) as a non-invasive gold standard. Methods: 175 subjects with T2D, >50 years or >40 yearswith diabetes duration >10 years, were included. ABI&TBI were measured with an automated vascular Doppler XT 6 ports (Hadeco Inc. Japan). ABI < 0.9 & TBI < 0.6 was considered abnormal. USG Color Doppler& CTA of lower limb arterial system was performed. Arterial stenosis >50% on CTA was taken as evidence of PAD. Statistical analysis was performed by using IBM-SPSS statistics version 26 & GraphPad Prism Software version 9.0e. Results: Theprevalence of PAD was 24%. The sensitivity& NPV of 38% and 80% respectively for ABI (<0.9) reflect an increased risk of failure to diagnose existing disease. The sensitivity of TBI was 90% indicating that TBI was quite likely to accurately detect PAD. The specificity of ABI and TBI were 90% and 85% respectively suggesting both were relatively unlikely to falsely detect PAD. ROC analysis showed ABI at 0.9950 has sensitivity 60% and specificity 70%, TBI at 0.6 has sensitivity 88% & specificity 86%. Conclusion: The prevalence of PAD in T2D is much higher in our study population compared to previous studies. We showed, TBI has much greater sensitivity and comparable specificity to ABI in participants at risk of PAD making it a useful tool for vascular assessment in people with T2D. The existing TBI cutoff is satisfactory and the ABI cutoff needs to be re-evaluated.{Table 1}