Table 1. Distribution of the trace elements in the case and control groups and univariate analysis for the associations between trace elements and schizophrenia by conditional logistic regression models.

Trace Element	Cases	Controls	OR (95%CI)	P-value
Iron, μg/mL
≤0.86	21	7	3.044 (1.102–8.408)	0.032
0.86~1.87	82	83	1.000
>1.87	11	24	0.457 (0.186–1.119)	0.086
Copper, μg/mL
≤0.97	92	60	5.166 (2.297–11.618)	<0.001
0.97~1.64	21	47	1.000
>1.64	1	7	0.255 (0.029–2.216)	0.215
Selenium, ng/mL
≤72	86	13	40.768 (9.557–173.908)	<0.001
72~224	27	98	1.000
>224	1	3	3.368 (0.131–86.380)	0.463
Zinc, μg/mL
≤0.67	19	23	0.794 (0.418–1.509)	0.482
0.67~1.83	93	87	1.000
>1.83	2	4	0.481 (0.088–2.638)	0.399
Arsenic, ng/mL
≤20	46	6	12.434 (3.827–40.395)	<0.001
20~43	59	80	1.000
>43	9	28	0.464 (0.201–1.068)	0.071
Aluminum, μg/mL
≤0.11	46	82	1.000
0.11~0.78	66	30	3.790 (2.054–6.995)	<0.001
>0.78	2	2	2.766 (0.341–22.419)	0.341
Chromium, ng/mL
≤0.20	3	2	1.953 (0.314–12.131)	0.473
0.20~2.00	49	66	1.000
>2.00	62	46	1.891 (1.075–3.326)	0.027
Nickel, ng/mL
≤2.6	41	0	-*	<0.001
2.6~7.8	54	59	1.000
>7.8	19	55	0.350 (0.148–0.828)	0.017
Manganese, ng/mL
≤2.36	6	38	0.837 (0.255–2.752)	0.770
2.36~3.95	8	39	1.000
>3.95	100	37	29.882 (6.628–134.722)	<0.001
Molybdenum, ng/mL
≤1.59	57	38	1.754 (0.933–3.296)	0.081
1.59~2.07	32	39	1.000
>2.07	25	37	0.790 (0.375–1.662)	0.534

*means that the OR and 95%CI cannot be calculated as one cell was zero.