Table 2.

Multivariate linear regression analysis of the 38 potential biomarkers.

Model	Variable	Β b	P c	Adjusted R2	Durbin–Watson
Model 1	Constant a	−1.324	4.00 × 10−3	0.857	2.067
	Indole-3-carboxaldehyde	3.87 × 10−7	1.99 × 10−14
Model 2	Constant a	1.767	4.70 × 10−2	0.904
	Indole-3-carboxaldehyde	2.56 × 10−7	7.06 × 1−7
	Uridine monophosphate	−5.96 × 10−7	0
Model 3	Constant a	2.014	1.50 × 10−2	0.921
	Indole-3-carboxaldehyde	2.87 × 10−7	4.39 × 10−8
	Uridine monophosphate	−7.47 × 10−7	2.41 × 10−5
	S-phenylmercapturic acid	−2.30 × 10−7	1.20 × 10−2
Model 4	Constant a	3.356	0	0.939
	Indole-3-carboxaldehyde	2.46 × 10−7	3.07 × 10−7
	Uridine monophosphate	−7.56 × 10−7	3.22 × 10−6
	S-phenylmercapturic acid	−2.41 × 10−7	3.00 × 10−3
	Gluconic acid	−7.87 × 10−8	5.00 × 10−3
Model 5	Constant a	2.796	0	0.962
	Indole-3-carboxaldehyde	2.37 × 10−7	1.20 × 10−8
	Uridine monophosphate	−5.16 × 10−7	0
	S-phenylmercapturic acid	−3.23 × 10−7	2.47 × 10−5
	Gluconic acid	−9.42 × 10−8	0
	Tyramine	1.27 × 10−8	0
Model 6	Constant a	3.964	1.76 × 10−5	0.969
	Indole-3-carboxaldehyde	1.97 × 10−7	9.48 × 10−7
	Uridine monophosphate	−4.22 × 10−7	1.00 × 10−3
	S-phenylmercapturic acid	−3.37 × 10−7	4.11 × 10−6
	Gluconic acid	−8.80 × 10−8	8.62 × 10−5
	Tyramine	1.26 × 10−8	0
	Serylphenylalanine	−5.57 × 10−7	1.60 × 10−2

^a constant in each model; ^b significance level of each variable; ^c unstandardized regression coefficient.