What ABI cutoff indicates severe arterial disease?

The ankle-brachial index (ABI) is a useful test for assessing the severity of arterial disease, particularly in the context of peripheral artery disease (PAD). An ABI measurement is calculated by comparing the blood pressure in the ankle with the blood pressure in the arm. A lower ABI value indicates more severe arterial obstruction.

An ABI of less than 0.5 is considered a strong indicator of severe arterial disease. This threshold suggests significant arterial narrowing or blockage, which can lead to inadequate blood flow to the lower limbs. Patients with such low ABI values are at a higher risk for critical limb ischemia and potential complications, including non-healing ulcers and even limb loss if left untreated.

In contrast, an ABI between 0.5 and 0.8 indicates moderate arterial disease, where there is still some blood flow, but significantly reduced compared to normal. An ABI of 0.9 to 1.0 is generally regarded as normal or only mildly compromised blood flow. Values greater than 1.0 may suggest the presence of non-compressible arteries, commonly seen in patients with diabetes or vascular calcifications, but do not indicate severe arterial disease.

Therefore, the cutoff of less than 0.5 is key in identifying patients who require