Table 4 Prediction of HFNC success based on cut-offs
|  | Sensitivity (%) | Specificity (%) | NPV (%) | PPV (%) | LR +  | LR- | Youden index |
|---|---|---|---|---|---|---|---|
2 h ROX > 12.40 | 65.7 | 85.7 | 34.3 | 95.7 | 4.59 | 0.40 | 0.514 |
2 h ROX-HR > 12.13 | 71.6 | 85.7 | 38.7 | 96.0 | 5.01 | 0.33 | 0.573 |
2 h ROX-HR Flow > 12.25 | 77.6 | 85.7 | 44.4 | 96.3 | 5.43 | 0.26 | 0.633 |
Post-HFNC POX-HR flow > 10.45# | 74.2 | 76.9 | 38.5 | 93.9 | 3.21 | 0.34 | 0.511 |