Table 2.

ROC curve analyses of responses in terms of lung aeration at each observed session for prediction of treatment success

Variable	AUC (95% CI)	p	Cut-off	Sens	Spec	LR +	LR—
Day 1
Δ-Dorsal LUS	0.75 (0.69–0.88)	< 0.001	<  − 1	80	60	2.04	0.33
Δ-ROX index	0.65 (0.52–0.76)	0.05	> 0.5	55	88	4.67	0.51
Δ-RR	0.53 (0.41–0.65)	0.67	<  − 1	40	72	1.46	0.83
Δ-SpO2/FiO2 ratio	0.65 (0.53–0.76)	0.04	> 7	50	84	3.19	0.59
Day 2
Δ-Dorsal LUS	0.63 (0.50–0.74)	0.07	<  − 2	78	43	1.39	0.49
Δ-ROX index	0.75 (0.63–0.84)	< 0.001	> 1.2	89	54	1.98	0.19
Δ-RR	0.66 (0.53–0.77)	0.02	<  − 1	63	64	1.79	0.57
Δ-SpO2/FiO2 ratio	0.66 (0.53–0.77)	0.03	> 1.1	47	86	3.45	0.61
Day 3
Δ-Dorsal LUS	0.51 (0.39–0.63)	0.86	<  − 2	15	90	1.61	0.93
Δ-ROX index	0.57 (0.44–0.69)	0.32	> 1.8	100	23	1.31	0
Δ-RR	0.67 (0.54–0.77)	0.01	<  − 2	26	98	13.4	0.75
Δ-SpO2/FiO2 ratio	0.60 (0.48–0.72)	0.12	> 15	89	39	1.47	0.27
Whole 3 days
Δ-Dorsal LUS	0.72 (0.62–0.84)	0.005	<  − 1	50	82	2.83	0.61
Δ-ROX index	0.84 (0.73–0.92)	< 0.001	> 0.3	50	90	5.10	0.55
Δ-RR	0.71 (0.59–0.82)	0.005	< 0	57	84	3.69	0.50
Δ-SpO2/FiO2 ratio	0.77 (0.64–0.86)	< 0.001	> 42	100	51	2.04	0

Δ-Dorsal LUS change in lung ultrasound score after the APP session; Δ-ROX change in ROX index after the APP session; Δ-RR change in respiratory rate after the APP session; Δ-SpO₂/FiO₂ ratio change in SpO₂/FiO₂ ratio after the APP session; AUC area under the curve; Sens sensitivity; Spec specificity; LR + positive likelihood ratio; LR − negative likelihood ratio