Calcaneal quantitative ultrasound and Phalangeal radiographic absorptiometry alone or in combination in a triage approach for assessment of osteoporosis: a study of older women with a high prevalence of falls

Table 3 Accuracy of calcaneal QUS in predicting osteoporosis

Calcaneal QUS (n = 221)	Youden¹	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.

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