Table 2. Estimating the predictive power of variables using the area under a receiver operating characteristic curve (AUC).
The p value indicates asymptotic significance with the null hypothesis being that the true AUC is equal to 0.5. The far-right column shows whether the variable is elevated or decreased in autistic patients (ASD) compared to healthy controls. PC1: first principal component in a principal component analysis used as a multivariate biomarker profile. The number of individual biomarkers used in each profile is indicated. The 9 biomarkers (K, Na, LDH, GLTN, GST, CK, CoQ10, Cas7, and MLTN); 7 biomarkers (K, Na, LDH, GSH, CK, CoQ10, and MLTN); 5 ratios (K:Na, GST:GLTN, CK:Cas7, CoQ10: Cas7, and Cas7:MLTN); 9 biomarkers and 5 ratios; or K, GST, and Cas7.
| Variable | AUC | p value | In ASD |
|---|---|---|---|
| Potassium (K) | 0.813 | 0.001923 | Decreased |
| Sodium (Na) | 0.71 | 0.037175 | Elevated |
| K:Na ratio | 0.803 | 0.002643 | Decreased |
| Lactate dehydrogenase (LDH) | 0.758 | 0.010436 | Elevated |
| Glutathione (GSH) | 0.756 | 0.010923 | Decreased |
| Glutathione S-transferase (GST) | 0.973 | 0.000003 | Elevated |
| GST:GSH ratio | 0.91 | 0.000047 | Decreased |
| Creatine kinase (CK) | 0.716 | 0.031757 | Elevated |
| Co-enzyme Q10 (CoQ10) | 0.744 | 0.015611 | Elevated |
| Caspase 7 (Cas7) | 1 | <0.000001 | Elevated |
| Melatonin (MLTN) | 0.739 | 0.01778 | Elevated |
| CK:Cas7 ratio | 0.893 | 0.000097 | Decreased |
| CoQ10: Cas7 ratio | 0.798 | 0.003089 | Decreased |
| Cas7:MLTN ratio | 1 | <0.000001 | Elevated |
| PC1 9 biomarkers | 1 | <0.000001 | Elevated |
| PC1 7 biomarkers | 0.936 | 0.000015 | Elevated |
| PC1 5 ratios | 1 | <0.000001 | Elevated |
| PC1 9 biomarkers + 5 ratios | 1 | <0.000001 | Elevated |