Fig. 4

Significant correlations and cutoff points. a Correlation between hypoxemia on exertion during the CS-1 and hospitalization. Spearman rank correlation test, ρ = 0.60, P < 0.01. b Receiver operating characteristic curve for ΔSpO₂ during the CS-1. AUC = 0.94, 95% CI = 0.88–1.00, P < 0.01. Cutoff point of ΔSpO₂ during the CS-1 = 9.5%. CS-1, one-time chair stand test; SpO₂, oxygen saturation