Comparison of resting/postexercise ankle-brachial index and transcutaneous partial pressure of oxygen for noninvasive diagnosis of peripheral artery disease in type 2 diabetes mellitus

Background Type 2 diabetes

Type 2 diabetes mellitus (T2DM) is a strong risk factor for peripheral artery disease (PAD) and PAD diagnosis in T2DM may indicate coexisting coronary artery disease as well. Postexercise ankle brachial index (ABI) and transcutaneous partial pressure of oxygen (TcPO2) have not been evaluated for PAD diagnosis among Indian T2DM patients. This study aimed to evaluate the performance of resting + postexercise(R + PE) ABI and R + PE-TcPO2 for PAD diagnosis among T2DM patients at increased PAD risk, using colour duplex ultrasound (CDU) as reference standard.

Methods

This prospectively conducted diagnostic accuracy study involved T2DM patients at increased PAD risk. R-ABI≤0.9 or PE-ABI decline >20% from resting value in those with R-ABI between 0.91 and 1.4, R-TcPO2 <30 mm Hg or PE decline of TcPO2 to <30 mm Hg in those with R-TcPO2 ≥30 mm Hg, CDU showing >50% stenosis or complete occlusion of lower extremity arteries constituted PAD.

Results

Among 168 patients enrolled, R + PE-ABI diagnosed PAD in 19(11.3%), R + PE-TcPO2 in 61 (36.3%) and 17 (≈10%) had PAD finally confirmed by CDU. Sensitivity, specificity, PPV and NPV of R + PE-ABI for PAD diagnosis were 82.3%, 96.7%, 73.7% and 98% and that of R + PE-TcPO2 were 76.5%, 68.2%, 21.3% and 96.2%, respectively. PE-ABI increased the sensitivity of ABI by ≈ 18% and had 100% PPV for PAD. When both ABI and TcPO2 (R + PE tests) were normal, PAD could be safely excluded in 88% of patients.

Conclusion

PE-ABI should be routinely employed and TcPO2(R/PE) is unreliable as a stand-alone test for PAD detection among moderate to high risk T2DM patients.