A modified calculation of ankle-brachial pressure index is far more sensitive in the detection of peripheral arterial disease.
BACKGROUND
Ankle-brachial pressure index (ABI) is a simple, inexpensive, and useful tool in the detection of peripheral arterial occlusive disease (PAD). The current guidelines published by the American Heart Association define ABI as the quotient of the higher of the systolic blood pressures (SBPs) of the two ankle arteries of that limb (either the anterior tibial artery or the posterior tibial artery) and the higher of the two brachial SBPs of the upper limbs. We hypothesized that considering the lower of the two ankle arterial SBPs of a side as the numerator and the higher of the brachial SBPs as the denominator would increase its diagnostic yield.


METHODS
The former method of eliciting ABI was termed as high ankle pressure (HAP) and the latter low ankle pressure (LAP). ABI was assessed in 216 subjects and calculated according to the HAP and the LAP method. ABI findings were confirmed by arterial duplex ultrasonography. A significant arterial stenosis was assumed if ABI was <0.9.


RESULTS
LAP had a sensitivity of 0.89 and a specificity of 0.93. The HAP method had a sensitivity of 0.68 and a specificity of 0.99. McNemar's test to compare the results of both methods demonstrated a two-tailed P < .0001, indicating a highly significant difference between both measurement methods.


CONCLUSIONS
LAP is the superior method of calculating ABI to identify PAD. This result is of great interest for epidemiologic studies applying ABI measurements to detect PAD and assessing patients' cardiovascular risk.
Schröder
Frank
F
Department of Internal/Vascular Medicine, Klinikum Karlsbad, Langensteinbach, Germany.
Diehm
Nicolas
N
Kareem
Shiraz
S
Ames
Michael
M
Pira
Alessandro
A
Zwettler
Uwe
U
Lawall
Holger
H
Diehm
Curt
C
D000368:Aged; D015901:Angiography, Digital Subtraction; D001157:Arterial Occlusive Diseases / Q000175:diagnosis* / Q000503:physiopathology; D001794:Blood Pressure; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000502:physiology*; D006801:Humans; D007866:Leg / Q000098:blood supply; D008875:Middle Aged; D012039:Regional Blood Flow; D012680:Sensitivity and Specificity; D018615:Ultrasonography, Doppler, Color