Table 1.

The characteristics of patients.

Variable	Total (n = 782)	Training Set (n = 625)	Testing Set (n = 157)	p
Hepatotoxicity
Yes	279	223	56	1.00
No	503	402	101
Gender
Male	352	281	71	1.00
Female	430	344	86
Age (years)	47.85 ± 15.56 (10–87)	47.67 ± 15.63 (14–78)	48.58 ± 15.33 (10–87)	0.40
First time taking MTX
Yes	501	400	101	1.00
No	272	225	56
Body mass index * (kg/m2)	Original data
	729	586	143
	22.72 ± 3.91 (13.27–41.14)	22.78 ± 3.94 (13.27–41.14)	22.45 ± 3.77 (13.74–37.13)	0.71
	Processed data
	22.68 ± 3.81 (13.27–41.14)	22.77 ± 3.86 (13.27–41.14)	22.38 ± 3.23 (13.74–37.13)	0.37
Alcohol use
Yes	164	130	34	0.83
No	618	495	123
History of kidney disease
Yes	6	5	1	1.00
No	776	620	156
History of liver disease
Yes	32	23	9	0.26
No	750	602	148
Number of comorbidities	4.98 ± 2.97 (1–17)	4.90 ± 2.90 (1–17)	5.28 ± 3.23 (1–16)	0.69
Type 2 diabetes
Yes	69	59	10	0.27
No	713	566	147
Hyperlipidemia
Yes	41	30	11	0.32
No	741	595	146
Folate supplementation
Yes	723	575	148	0.40
No	59	50	9
Doses of folic acid/week	9.19 ± 3.33 (0–35)	9.16 ± 3.39 (0–35)	9.29 ± 3.07 (0–15)	0.05
NSAIDs use
Yes	276	231	45	0.06
No	506	394	112
Glucocorticoid use
Yes	441	350	91	0.72
No	341	275	66
Antibiotics use
Yes	153	117	36	0.26
No	629	508	121
Other immunosuppressive agent use
Yes	446	351	95	0.37
No	336	274	62
Number of medications	5.91 ± 2.93 (0–24)	5.97 ± 2.93 (0–24)	5.67 ± 2.92 (0–18)	0.92
Chinese patent medicines use
Yes	68	56	12	0.75
No	714	569	145

*: The difference between processed data and original data was not statistically significant (p values were 0.88, 0.94, and 0.87 in the total, training set, and testing set, respectively). NSAID: non-steroidal anti-inflammatory drugs.