Table 2 Receiver-operating characteristic analysis and cut-off thresholds for RFM ultrasound measurements for predicting frailty (CFS > 4)
| Â | Cut-off | Sensitivity (95% CI) | Specificity (95% CI) | Positive Likelihood Ratio (95% CI) | Negative Likelihood Ratio (95% CI) | AUROC (95% CI) |
|---|---|---|---|---|---|---|
Muscle thickness; cm | ||||||
 Mean of dominant and non-dominant legs |  ≤ 1.400 | 90.9 (58.7–99.8) | 50.0 (38.1–61.9) | 1.82 (1.35–2.44) | 0.18 (0.03–1.19) | 0.75 (0.64–0.84) |
 Mean (normalised by BMI) |  ≤ 0.046 | 54.6 (23.4–83.3) | 78.4 (67.3–87.1) | 2.52 (1.26–5.04) | 0.58 (0.30–1.12) | 0.64 (0.53–0.74) |
 Mean (normalised by BSA) |  ≤ 0.880 | 100.0 (71.5–100.0) | 28.4 (18.5–40.1) | 1.40 (1.21–1.61) | 0.00 | 0.66 (0.55–0.76) |
Muscle cross-sectional area; cm2 | ||||||
 Mean of dominant and non-dominant legs |  ≤ 3.015 | 63.6 (30.8–89.1) | 93.2 (84.9–97.8) | 9.42 (3.62–24.53) | 0.39 (0.18–0.85) | 0.76 (0.66–0.85) |
 Mean (normalised by BMI) |  ≤ 0.190 | 90.9 (58.7–99.8) | 52.7 (40.7–64.4) | 1.92 (1.42–2.61) | 0.17 (0.03–1.13) | 0.74 (0.63–0.83) |
 Mean (normalised by BSA) |  ≤ 2.056 | 63.6 (30.8–89.1) | 87.8 (78.2–94.3) | 5.23 (2.45–11.17) | 0.41 (0.19–0.91) | 0.75 (0.64–0.83) |
Muscle echogenicity; au | ||||||
 Mean of dominant and non-dominant legs |  > 45.85 | 54.6 (23.4–83.3) | 75.7 (64.3–84.9) | 2.24 (1.14–4.39) | 0.60 (0.31–1.16) | 0.61 (0.50–0.72) |