Establishing and clinically validating a machine learning model for predicting unplanned reoperation risk in colorectal cancer

Table 3 Comparison of baseline data between training group and validation group

	Training group (n = 1429)	Validation group (n = 615)	χ2	P value
Reoperation
Yes	40	20	0.309	0.578
No	1389	595
Age (yr)
≥ 60	853	346	2.088	0.148
< 60	576	269
Gender
Male	817	357	0.135	0.713
Female	612	258
BMI (kg/m2)
≥ 24	891	395	0.649	0.421
< 24	538	220
History of hypertension
Yes	451	191	0.051	0.822
No	978	424
History of diabetes
Yes	164	80	0.959	0.327
No	1265	535
History of stroke
Yes	174	73	0.038	0.845
No	1255	542
History of laparotomy
Yes	248	109	0.041	0.840
No	1181	506
Hypoproteinemia
Yes	144	49	2.238	0.135
No	1285	566
Location of the tumor
Colon	894	392	0.256	0.613
Rectum	535	223
History of preoperative radiation therapy
Present	144	61	0.012	0.913
No present	1285	554
History of preoperative chemotherapy
Present	173	73	0.023	0.880
No present	1256	542
TNM staging
I + II	825	378	2.471	0.116
III + IV	604	237
ASA classification
I + II	1281	556	0.275	0.600
III + IV	148	59
Surgical time (min)
≥ 240	476	229	2.933	0.087
< 240	953	386
Intraoperative bleeding (mL)
≥ 120	145	77	2.502	0.114
< 120	1284	538
PNI
≥ 43.76	487	207	0.034	0.854
< 43.76	942	408

TNM: Tumor-node-metastasis; BMI: Body mass index; ASA: American Society of Anesthesiologists; PNI: Prognostic nutritional index.