Table II.
Accuracy of resting ankle-brachial index (ABI) in detecting 50% or greater stenosis according to duplex ultrasound (DUS) imaging (excluding inconclusive ABI)
| ≥50 Stenosis | Sensitivity | Specificity | PPV | NPV | Accuracya | P value for accuracyb |
|---|---|---|---|---|---|---|
| All patients | 69 (65.2–72.9) | 89 (86.6–91.6) | 86 (82.5–88.3) | 76 (73.5–78.1) | 80 (77.2–81.9) | |
| Diabetics | ||||||
| Diabetics | 67 (61.6–72.7) | 85 (79.7–90.1) | 88 (83.1–90.9) | 63 (59.3–67.4) | 75 (70.5–78.4) | .0003 |
| Nondiabetics | 71 (65.3–76.3) | 91 (87.9–93.6) | 84 (79.1–87.6) | 83 (80.0–85.3) | 83 (80.1–85.8) | |
| CKD | ||||||
| CKD | 63 (51.3–73.0) | 94 (85.8–97.9) | 91 (81.4–96.1) | 70 (64.2–76.0) | 78 (70.6–83.9) | .5291 |
| Non-CKD | 70 (66.0–74.3) | 89 (85.7–91.2) | 85 (81.4–87.7) | 77 (74.2–79.2) | 80 (77.3–82.3) | |
| Diabetics and CKD | ||||||
| Diabetics and CKD | 57 (43.2–69.8) | 93 (80.1–98.5) | 92 (78.3–97.1) | 60 (52.8–67.4) | 72 (61.8–80.3) | .0412 |
| Nondiabetics and CKD | 71 (66.4–74.5) | 89 (86.2–91.5) | 85 (81.8–87.9) | 77 (74.8–79.7) | 80 (77.9–82.7) | |
| <80 Years of age | 69 (64.3–72.7) | 90 (86.9–92.1) | 85 (81.8–88.1) | 77 (74.3–79.1) | 80 (77.4–82.3) | .5067 |
| ≥80 Years of age | 73 (61.4–81.9) | 85 (72.4–93.3) | 88 (79.1–93.3) | 67 (58.5–74.8) | 77 (69.4–84.2) |
CKD, Chronic kidney disease; NPV, negative predictive value; PPV, positive predictive value.
Values are presented as percentages (95% confidence interval).
a
Accuracy = (True positive + True negative)/(True positive + True negative + False positive + False negative).
b
χ2 test.