Table 3.
Accuracy of calcaneal QUS in predicting osteoporosis
| Calcaneal QUS (n = 221) | Youden 1 | UK-NOS triage approach 90% certainty level | UK-NOS triage approach 95% certainty level |
|---|---|---|---|
| BUA upper/lower cutoff | 93.88 | 105.88/86.63 | 114.5/80.09 |
| Sensitivity (95% CI) | 74.0 (64.3–82.3) | 90.0 (82.7–95.1) | 95.0 (88.7–98.4) |
| Specificity (95% CI) | 78.5 (70.1–85.5) | 90.1 (83.3–94.8) | 95.0 (89.5–98.2) |
| PPV (95% CI) | 74.0 (64.3–82.3) | 80.6 (68.6–89.6) | 83.3 (67.2–93.6) |
| NPV (95% CI) | 78.5 (70.1–85.5) | 85.7 (74.3–92.9) | 88.1 (74.4–96) |
| False negative n (%) | 26 (11.8) | 10 (4.5) | 5 (2.3) |
| False positive n (%) | 26 (11.8) | 12 (5.4) | 6 (2.7) |
| DXA scans avoided n (%) | NA | 132 (59.7) | 78 (35.3) |
Accuracy of calcaneal QUS in predicting osteoporosis applying the optimal cutoff and UK-NOS triage approach at 90% and 95% certainty levels. 1The optimal cutoff calculated according the Youden index [30]. Abbreviations: QUS Quantitative Ultrasound, BUA Broadband Ultrasound Attenuation, UK-NOS United Kingdom National Osteoporosis Society, PPV Positive Predictive Value, NPV Negative Predictive Value, DXA Dual Energy X-ray Absorptiometry, CI Confidence Interval, NA not available.