Table 1.

ROC analysis of metabolomic biomarkers and combined variates.

	AUC	Std. error	Asymptotic 95% confidence interval		Optimal cut off	Sensitivity	Specificity	Youden index
			Lower bound	Upper bound
ROC analysis of metabolomic biomarkers and combined variates in early lung tumor detection.
L-Kynurenine	0.825	0.043	0.740	0.909	0.975	85.2%	72.1%	0.573
Proline	0.923	0.026	0.871	0.975	24.350	79.6%	93.0%	0.727
Spermidine	0.890	0.035	0.821	0.958	7.195	81.5%	90.7%	0.722
Amino-hippuric acid	0.811	0.045	0.722	0.900	4.035	68.5%	93.0%	0.615
Palmitoyl-l-carnitine	0.906	0.032	0.843	0.969	3.655	74.1%	100.0%	0.741
Taurine	0.920	0.032	0.856	0.983	71.300	88.9%	95.3%	0.842
Phenylalanine	0.848	0.038	0.774	0.922	125.500	79.6%	76.7%	0.564
L-Valine	0.876	0.036	0.806	0.946	167.000	68.5%	95.3%	0.639
o-Tyr	0.822	0.043	0.738	0.906	24.650	83.3%	72.1%	0.554
Carnitine	0.848	0.040	0.769	0.926	4.680	72.2%	93.0%	0.652
Combination of two	0.933	0.028	0.878	0.978	0.337	85.2%	93.0%	0.782
Combination of three	0.968	0.019	0.931	1.000	−0.147	94.4%	97.7%	0.921
Combination of six	0.989	0.011	0.967	1.000	−0.102	98.1%	100.0%	0.981
ROC analysis of metabolomic biomarkers and combined variates of adenocarcinoma and squamous carcinoma patients.
L-Kynurenine	0.423	0.060	0.306	0.540	1.050	77.8%	24.4%	0.022
Proline	0.580	0.057	0.469	0.692	35.150	54.0%	65.9%	0.198
Carnitine	0.536	0.058	0.422	0.650	6.835	38.1%	75.6%	0.137
Hypoxanthine	0.639	0.055	0.531	0.746	0.092	69.8%	56.1%	0.259
Hippuric acid	0.628	0.056	0.519	0.737	2.620	49.2%	77.5%	0.267
Combination of four	0.740	0.049	0.644	0.837	0.556	58.7%	78.0%	0.368

Abbreviations: ROC,receiver operating characteristic; AUC, area under the curve.