Table 4.

Joint association between tryptophan and phenylalanine levels with arsenic-induced skin lesions

Tryptophan <cut-off value*	Phenylalanine <cut-off value*	N	Cases (%)	Crude		Adjusted†
				Or (95% CI)	P value	Or (95% CI)	P value
Yes	Yes	35	26 (74.3)	1.00 (1.00 to 1.00)	Ref.	1.00 (1.00 to 1.00)	Ref.
No	Yes	20	12 (60.0)	0.52 (0.16 to 1.68)	0.273	0.49 (0.15 to 1.63)	0.244
Yes	No	24	12 (50.0)	0.35 (0.12 to 1.04)	0.059	0.32 (0.10 to 1.02)	0.053
No	No	33	6 (18.2)	0.08 (0.02 to 0.25)	<0.001	0.08 (0.02 to 0.25)	<0.001
Interaction					0.320	0.49 (0.09 to 2.78)	0.419

*Adjusted for plasma glucose, low-density lipoprotein, triglyceride and urinary dimethyl arsenate.

†Cut-off value was determined using receiver operator characteristic analysis.