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Validation of QuantaFlo as a Screening Tool for Peripheral Artery Disease
Brianna Hayden
1, Swathi Raikot
2, Madhur Sancheti
3, Debra Dice
3, Brandi M. Mize
2, Arash Harzand
4, Yazan Duwayri
2, Wilbur Lam
5, Christopher Bain
6, Olamide Alabi
2 1Morehouse School of Medicine, Atlanta, GA;
2Division of Vascular Surgery and Endovascular Therapy, Department of Surgery, Emory University School of Medicine, Atlanta, GA;
3Atlanta VA Healthcare System, Decatur, GA;
4Division of Cardiology, Emory University School of Medicine, Atlanta, GA;
5Division of Pediatric Hematology/Oncology, Children’s Healthcare of Atlanta, Emory University School of Medicine, Atlanta, GA;
6Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA
BACKGROUND: Although the ankle-brachial index (ABI) remains the gold standard for noninvasive testing in peripheral artery disease (PAD), volume plethysmography (e.g., QuantaFlo, S
emler Scientific, approved for point-of-care use by the FDA
) is increasingly used as a simpler alternative in non-clinical settings
. We evaluated QuantaFlo's feasibility as a screening tool compared to ABI.
METHODS: As part of a prospective cohort study to evaluate the prediction of PAD progression, patients seen at an ambulatory Veterans Affairs clinic were enrolled from October 2023 to July 2024. We excluded patients with prior revascularization or major amputation. A registered vascular sonographer performed QuantaFlo and ABI tests with patients lying supine in a dimly lit room between 68-70°F. Sensitivity, specificity, and positive and negative predictive values (PPV, NPV) were calculated. We considered a normal ABI ratio with normal ankle and toe waveforms to be a ‘normal’ result.
RESULTS: We enrolled 130 limbs (18 controls) with a median[IQR] age of 69 [63,77]; 94% were male, 60% were Black, 29% never smoked, 60% had diabetes mellitus, and 29% had advanced kidney disease. QuantaFlo required less time to perform compared to ABI (2.2min [1.8,3.2] vs. 21.1min [19.2,25.3], p < 0.001), with a median difference of 18.8min [16.5,21.97].
Table 1 displays a comparative cross-tabulation of both tests. Among diabetics, the median QuantaFlo value was 0.6 [0.3,1.1], median ABI was 0.8 [0.6,1.1], and median toe pressure was 61mmHg [8.5,89.0] compared to a median QuantaFlo value of 0.9 [0.4,1.1], median ABI of 1.0 [0.7,1.3], and median toe pressure of 88.0mmHg [53.0,123.5] in non-diabetics. For all participants, QuantaFlo had a sensitivity of 76%, specificity of 90%, PPV of 98%, and NPV of 40%. For diabetics, QuantaFlo had a sensitivity of 79%, specificity of 88%, PPV of 98%, and NPV of 30%.
CONCLUSION: When performed under ideal laboratory conditions, QuantaFlo is a reasonable screening tool for PAD. However, further investigation is necessary to determine its real world performance in community settings or for home-based PAD screening.
Table 1. Cross-tabulation of Quantaflo results with Ankle-Brachial Index and Toe Pressures| | Ankle-brachial Index |
| QuantaFlo | Total(N=130) | ≤0.5(N=14) | 0.5 - 0.8 (N=44) | >1.4/non-compressible (N=18) | 0.9 - 1.4(normal)(N=54) | < 0.001 | |
| 0.00-0.29 (severe) | 32 (24.6%) | 10 (71.4%) | 15 (34.1%) | 3 (16.7%) | 4 (7.4%) | | |
| 0.30-0.59 (moderate) | 28 (21.5%) | 3 (21.4%) | 15 (34.1%) | 4 (22.2%) | 6 (11.1%) | | |
| 0.60-0.89 (mild) | 16 (12.3%) | 0 (0.0%) | 8 (18.2%) | 2 (11.1%) | 6 (11.1%) | | |
| 0.90-0.99 (borderline) | 9 (6.9%) | 1 (7.1%) | 3 (6.8%) | 0 (0.0%) | 5 (9.3%) | | |
| 1.00-1.40 (normal) | 45 (34.6%) | 0 (0.0%) | 3 (6.8%) | 9 (50.0%) | 33 (61.1%) | | |
| | Toe Pressure |
| QuantaFlo | Total(N=126)* | <30(N=18) | 30-39(N=8) | 40-59(N=23) | >=60(N=77) | < 0.001 | |
| 0.00-0.29 (severe) | 31 (24.6%) | 12 (66.7%) | 5 (62.5%) | 9 (39.1%) | 5 (6.5%) | | |
| 0.30-0.59 (moderate) | 27 (21.4%) | 6 (33.3%) | 2 (25.0%) | 7 (30.4%) | 12 (15.6%) | | |
| 0.60-0.89 (mild) | 15 (11.9%) | 0 (0.0%) | 0 (0.0%) | 4 (17.4%) | 11 (14.3%) | | |
| 0.90-0.99 (borderline) | 9 (7.1%) | 0 (0.0%) | 1 (12.5%) | 2 (8.7%) | 6 (7.8%) | | |
| 1.00-1.40 (normal) | 44 (34.9%) | 0 (0.0%) | 0 (0.0%) | 1 (4.3%) | 43 (55.8%) | | |
*Toe pressure was not obtained in 4 limbs secondary to transmetatarsal amputation, hallux amputation (n=2), or lack of patient immobility.
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