Toe Brachial Indices are an Accurate Peripheral Artery Disease Screening Tool in Vascular Deserts

Targeted cardiovascular screening in vascular deserts (VDs), defined as regions lacking vascular providers, is necessary to address issues of health literacy and poor access to care in high-risk socioeconomically disadvantaged populations. Guidelines suggest focused screening for peripheral artery disease (PAD) utilizing ankle brachial index (ABI) in appropriately selected patients, which requires skilled technicians. This study aims to evaluate toe brachial indices (TBIs) as an accurate way to effectively screen this patient population.

In 2023, vascular surgeons, surgical trainees, and medical students screened patients for PAD at events targeted in known VD. Demographics and risk factors for PAD were collected and assessed, and measures of lower extremity perfusion including ABI and TBI were collected. Screened patients were combined with 50 randomly selected retrospective patients seen in the vascular clinic (VC) as new consultations for a diagnosis of PAD who also underwent ABI/TBI testing. PAD was defined as an ABI < 0.9 or TBI < 0.7. Noncompressibility (NC) was defined as an ABI ≥ 1.4. Analysis of variance and correlation analyses were used to assess relationships between ABI and TBI overall and among patients without NC, stratified by diabetes status and intermittent claudication symptoms.

Ninety-nine patients were screened for PAD (49 VD, 50 VC). Five-six percent were male and 54% were Hispanic with only 58% having seen a primary care provider within the last year. The mean age was 60 ± 19 years, with 38% smokers and 36% with a previous diagnosis of diabetes or a screened HbA1c of >5.7%. Fifty percent of patients reported symptoms of possible intermittent claudication. Of screened patients, 8% had NC ABI's, and 36% had ABI <0.9. There were significant and graded associations of TBI with ABI: among patients with ABI <0.9, mean TBI was 0.38 (95% confidence interval [CI] 0.31, 0.45), compared to 0.90 (95% CI 0.84, 0.96) among patients with ABI between 0.9 and 1.4, and 1.33 (95% CI 1.18, 1.48) among patients with ABI >1.4 (P < 0.001). There was a strong correlation between ABI and TBI (Pearson's correlation coefficient [PCC] 0.82, P < 0.001) overall and among patients with measurable ABI (PCC 0.83, P < 0.001), but not among patients with NC ABIs (PCC 0.38). Results were similar in subgroups stratified by diabetes status and claudication symptoms (both, P < 001).

TBIs closely mirror ankle ABIs and are an efficient tool to screen for PAD. This method provides an accurate assessment of patients at risk for PAD, particularly those with diabetes mellitus and noncompressible vessels, and can provide valuable information to healthcare providers in VDs.