Comparison of colour duplex ultrasound and ankle-brachial pressure index measurements in peripheral vascular disease in type 2 diabetic patients with foot infections.

Background and Objectives : Peripheral vascular disease (PVD) is a common cause of morbidity and mortality and is reported to be more common among diabetic subjects compared to non-diabetic subjects. The aim of the study was to compare the specificity and sensitivity of ankle-brachial index (ABI) measured by peripheral doppler with the colour duplex ultrasound (CDU) for diagnosis of PVD. Methods : One hundred type 2 diabetic patients admitted to our diabetic centre with foot lesions underwent both colour duplex ultrasound and ankle-brachial index measurements. PVD was diagnosed if the individual had haemodynamically significant obstruction on CDU, or if the ABI was < 0.9. The sensitivity and specificity of ABI was determined using the CDU as `gold standard’. Results : The mean age of the study group was 59.5 ± 10.1 years and the mean duration of diabetes was 11.7 ± 8.1 years. Of the total 100 subjects, six subjects had calcification of peripheral vessels and they were not included while calculating for sensitivity and specificity of ABI. Twenty (21.3%) subjects diagnosed as PVD by the CDU were not classified as PVD by the ABI measurements. Conversely, only three subjects (3.2%) classified as PVD by ABI had normal arteries based on CDU scanning. Overall, ABI had low sensitivity (70.6%) but a high specificity (88.5%). The overall agreement between CDU and ABI was poor (k=0.20). Conclusion : ABI is a good initial screening tool but some patients with significant stenosis in lower extremities would be missed, if ABI measurement alone is used for diagnosis of PVD. (J Assoc Physicians India 2002;50:1240-1244)