Simultaneous inter-arm and inter-leg systolic blood pressure differences to diagnose peripheral artery disease: a diagnostic accuracy study

Abstract

Purpose: Inter-arm systolic blood pressure differences (IASBPD) and inter-leg systolic blood pressure differences (ILSBPD) have arisen as potential tools to detect peripheral artery disease (PAD) and individuals at high cardiovascular risk. This study aims to evaluate the diagnostic accuracy of IASBPD and ILSBPD to detect PAD, and whether IASBPD or ILSBPD improves diagnostic accuracy of the oscillometric ankle-brachial index (ABI).

Materials and methods: In this prospective study, eligible for inclusion were consecutive adults, with at least one of the following cardiovascular risk factors: diabetes, dyslipidemia, hypertension, smoking habit or age ≥65. IASBPD, ILSBPD and ankle-brachial index (ABI) were measured in all participants through four-limb simultaneous oscillometric measurements and compared with Doppler ABI (reference test, positive cut-off: ≤ 0.9).

Results: Of 171 subjects included, PAD was confirmed in 23 and excluded in 148. Thirteen and 38 subjects had IASBPD and ILSBPD ≥10 mmHg, respectively. Pearson correlation with Doppler ABI of IASBPD and ILSBPD was 0.073 (P = .343) and -0.628 (P < .001), respectively. Diagnostic accuracy of an ILSBPD ≥10 mmHg to detect PAD was: sensitivity = 69.6% (95%CI = 48.6-90.5), specificity = 85.1% (79.1-91.2), diagnostic odds ratio (dOR) = 13.1 (4.8-35.5) and area under ROC curve (AUC) = 0.765 (0.616-0.915). IASBPD had an AUC = 0.532 (0.394-0.669), and oscillometric ABI had an AUC = 0.977 (0.950-1.000). The addition of ILSBPD to oscillometric ABI reduced dOR from 174.0 (38.3-789.9) to 34.4 (9.5-125.1). Similarly, the addition of IASBPD reduced dOR to 49.3 (14.6-167.0).

Conclusions: In a Primary Care population with ≥1 cardiovascular risk factors, ILSBPD showed acceptable diagnostic accuracy for PAD, whilst IASBPD accuracy was negligible. However, the combination of ILSBPD (or IASBPD) with oscillometric ABI did not improve the ability to detect PAD. Thus, oscillometer ABI seems to be preferable to detect PAD and individuals at high cardiovascular risk. ILSBPD could be uniquely recommended for the diagnosis of PAD when blood pressure measurements in upper limbs are not possible.

Keywords: Ankle-brachial index; blood pressure; inter-arm systolic blood pressure difference; inter-leg systolic blood pressure difference; peripheral artery disease; sensitivity; specificity.