ABI derived from the highest and lowest ankle pressure. What is the difference?

Area of Science:

• Vascular Medicine
• Diagnostic Accuracy
• Epidemiology

Background:

• Ankle-brachial index (ABI) is crucial for diagnosing peripheral arterial disease (PAD).
• Different calculation methods for ABI, specifically ABI-low and ABI-high, yield varying prevalence estimates.
• Understanding these differences is vital for accurate PAD detection and risk assessment.

Purpose of the Study:

• To compare the prevalence of PAD estimated using ABI-low versus ABI-high.
• To analyze the influence of age and cardiovascular risk factors on PAD prevalence estimates.
• To investigate the underlying reasons for discrepancies between ABI-low and ABI-high in PAD prevalence.

Main Methods:

• Utilized data from the Arteriomobil Project.
• Calculated ABI using two methods: ABI-low (lowest of four ankle pressures) and ABI-high (highest ankle pressure per leg).
• Defined PAD as ABI < 0.9.

Main Results:

• PAD prevalence was significantly higher with ABI-low (15.7%) compared to ABI-high (8.0%).
• Using ABI-high alone missed 8% of men and 7.5% of women with suspected PAD.
• Prevalence rates remained low when using only posterior or anterior tibial artery pressures.
• ABI-high showed consistently lower prevalence, unaffected by age or common risk factors (smoking, hypertension, hypercholesterolemia, diabetes).

Conclusions:

• The study supports the hypothesis that anatomical variations in the plantar arch explain the differing PAD prevalence rates between ABI-low and ABI-high.
• Angiographic studies are recommended to confirm the role of plantar arch anatomy.
• Accurate ABI calculation method is critical for reliable PAD prevalence estimation.