Assessment of ABPI

The assessment of the ABPI is a simple, non-invasive clinical test to diagnose PAD.

ABPI was performed by measuring the systolic blood pressure from both brachial arteries and from the posterior- (PTA) and anterior-tibial (ATA) or the dorsalis pedis arteries. All measurements were performed with the use of appropriately sized pneumatic cuffs for both the ankle and the arm. The systolic ankle pressures were recorded with a handheld 5 MHz bi-directional pocket Doppler instrument by continuous wave (cw) velocity detection (Bidop ES-100V3, HADECO, Kawasaki, Japan). The ABPI was calculated for each lower limb as the ratio of the lowest pressure from the right or the left PTA and ATA (or dorsalis pedis) over the greatest brachial systolic pressure according to the following formula:

For each patient, only the lowest ABPI recorded in the two ankles was used for categorization into non-PAD and PAD groups. Ratios of > 0.90 to < 1.4 are considered normal, and ratios ≤ 0.9 indicate the presence of PAD [2,7,8,9]. For the present study, PAD severity is based on the following ABPI values: ABPI 0.75–0.90 = mild PAD; ABPI 0.50–0.75 = moderate PAD; ABPI < 0.50 = severe PAD.

In patients with an ABPI ≥ 1.4, which were considered to have medial calcific sclerosis with non-compressible arteries, the criteria for the classification into the PAD or non-PAD group were determined by additional toe-pressure measurements (TBI, see below).