Comparison of different baseline parameters for the prediction of an arterial oxygen tension (Pa,O2) at altitude of <6.6 kPa during moderate exercise using receiver-operating characteristic curves#
| AUC | 95% CI | Cut-off value | False-positive rate % | p-value | |
| MEF75 % pred | 0.93 | 0.82–1.04 | <58 | 8 | 0.001 |
| FEV1 % pred | 0.93 | 0.82–1.04 | <67 | 14 | 0.001 |
| MEF25 % pred | 0.91 | 0.78–1.04 | <19 | 25 | 0.002 |
| Tiffeneau index¶ | 0.90 | 0.77–1.03 | <66 | 17 | 0.003 |
| Pa,O2 after HIT kPa | 0.85 | 0.68–1.02 | <7.1 | 28 | 0.009 |
| Pa,O2 baseline kPa | 0.85 | 0.66–1.03 | <9.9 | 12 | 0.01 |
| Sa,O2 baseline % | 0.76 | 0.59–0.93 | <96 | 33 | 0.016 |
The cut-off values and false-positive rates correspond to a sensitivity of ≥75%. AUC: area under curve; CI: confidence interval; MEF75: maximal expiratory flow when 75% of the forced vital capacity (FVC) remains to be exhaled; FEV1: forced expiratory volume in one second; MEF25: maximal expiratory flow when 25% of the FVC remains to be exhaled; HIT: hypoxia inhalation test; Sa,O2: arterial oxygen saturation; % pred: percentage of the predicted value. #: the greater the AUC the better the predictive value of the baseline parameter (see fig. 2⇑); ¶: FEV1/FVC.