Table 4.

Receiver operating characteristic curves to assess the performance of the maximum oxygen consumption measured by cardiopulmonary exercise test and the maximum oxygen consumption estimated by smartwatch test in predicting acute mountain sickness.^a

	AUCb (95% CI)	Optimal cutoff values (mL·kg–1·min–1 or fL)	Sensitivity (%)	Specificity (%)	PPVc (%)	NPVd (%)
VO2max-CPETe	0.743 (0.597-0.889)	26.50	45	96.15	90	69.44
VO2max-SWTf	0.785 (0.646-0.923)	29.50	65	88.46	81.25	76.67
RDW-CVg	0.708 (0.547-0.868)	13.10	75	69.23	65.22	78.26
Model 1: VO2max-CPET + RDW-CV	0.804 (0.675-0.933)	N/Ah	65	92.31	87.50	77.42
Model 2: VO2max-SWT + RDW-CV	0.839 (0.720-0.959)	N/A	80	84.62	80	84.62

^aComparison of area under the curve: maximum oxygen consumption measured by cardiopulmonary exercise test versus maximum oxygen consumption estimated by smartwatch test (P=.25); Model 1 versus maximum oxygen consumption measured by cardiopulmonary exercise test (P=.22); Model 2 versus maximum oxygen consumption estimated by smartwatch test (P=.28); Model 1 versus Model 2 (P=.27).

^bAUC: area under the curve.

^cPPV: positive predictive value.

^dNPV: negative predictive value.

^eVO₂max-CPET: maximum oxygen consumption measured by cardiopulmonary exercise test.

^fVO₂max-SWT: maximum oxygen consumption estimated by smartwatch test.

^gRDW-CV: red blood cell distribution width-coefficient of variation.

^hN/A: not applicable.