Diagnostic potential of cardiopulmonary exercise testing in the exclusion of clinically significant lung and heart pathology
| Criteria | Accuracy | Sensitivity | Specificity | AUC | NPV |
| Slope >30 and peak predicted V̇O2<100% | 86% | 57% | 88% | 0.81 | 97% |
| OR slope >35 (slope >30 and peak predicted V̇O2<100%) | 83% | 86% | 83% | 0.89 | 99% |
| OR slope >35 OR A-a gradient >4.4 kPa (slope >30 AND peak predicted V̇O2 <100%) | 78% | 100% | 78% | 0.92 | 100% |
| Work predicted <85% | 82% | 86% | 82% | 0.84 | 99% |
Accuracy refers to the closeness of the CPET criteria to the frequency of normal or pathological findings on comprehensive clinical imaging. ‘Slope’ refers to the gradient of the function: ventilation (L/min) versus CO2 elimination (L/min)—a sensitive measure of ventilatory efficiency. A higher value indicates lower ventilatory efficiency. A-a gradient refers to the estimated gradient of oxygen between the alveoli (PAO2) and the arterial blood (PaO2) at the point of peak exertion. This is estimated using capillary blood testing from the earlobe. Level of significance for Fisher’s exact test of contingency tables **p<0.01; ***p<0.001.
AUC, area under the receiver operating characteristic curve; CPET, cardiopulmonary exercise testing; NPV, negative predictive value; VO2, oxygen uptake.