Flap failure prediction in microvascular tissue reconstruction using machine learning algorithms

Table 1 Patient characteristics

Variables	Training set	Test set	P value
Patient population, n	473	473
Age (yr)	41 (13-64)	43 (15-65)	0.115
Male, n (%)	274 (57.9)	278 (58.8)	0.258
BMI (kg/m2)	25.3(16.9-32.8)	25.9 (16.7-35.5)	0.079
Systolic blood pressure	119 (87-165)	121(85-177)	0.658
Smoking, n (%)	142 (30.0)	145 (30.7)	0.583
Alcohol, n (%)	163 (34.5)	172 (36.4)	0.158
Diabetes, n (%)	34 (7.2)	26 (5.5)	0.098
Insulin, n (%)	8 (1.7)	4 (0.8)	0.059
Hypertension, n (%)	73 (15.4)	80 (16.9)	0.113
Preoperative chemotherapy, n (%)	117 (24.7)	122 (25.8)	0.358
Preoperative radiotherapy, n (%)	100 (21.1)	82 (17.3)	0.663
Obesity, n (%)	112 (23.7)	109 (23.0)	0.487
WBC (× 103/µL)	7.5 (3.2-14.3)	7.2 (3.1-15.9)	0.226
Hemoglobin (mg/dL)	12.6 (9.8-16.6)	12.9 (10.1-16.9)	0.460
PLT (× 103/µL)	156 (102-253)	165 (113-267)	0.115
Creatinine (mg/dL)	0.89 (0.69-1.20)	0.83 (0.65-1.15)	0.328
Glucose (mg/dL)	10.5(5.1-16.5)	11.3 (4.4-18.8)	0.085
Cholesterol (mg/dL)	159.2 (137.3-195.3)	144.0 (127.4-199.8)	0.075
Beta blockers, n (%)	51 (10.8)	55 (11.6)	0.165
Aspirin, n (%)	43 (9.1)	47 (9.9)	0.392
Flap ischemia time (min)	123 (108-145)	117 (101-153)	0.558
Hypotensive events, n (%)	11 (2.3)	15 (3.2)	0.663

BMI: Body mass index; PLT: Platelet; WBC: White blood cell.

Table 2 The model performance of the machine learning classifiers for predicting flap failure

	Accuracy	Precision	Recall	F1 score	AUC
Random forest	0.78	0.82	0.69	0.75	0.770
Support vector machine	0.71	0.79	0.58	0.67	0.720
Gradient boosting	0.68	0.76	0.53	0.65	0.707

AUC: Area under the curve.

Table 3 Multivariate logistic regression model for top 10 variables in random forest

Variables	Odds ratio (95%CI)	P value
Age	1.56 (0.57-5.87)	0.04
Body mass index	2.83 (0.68-5.54)	0.02
Ischemia time	1.98 (0.53-3.24)	0.001
Smoking	1.13 (0.28-2.89)	0.87
Diabetes	1.15 (0.53-3.28)	0.06
Experience	0.86 (0.18-4.87)	0.79
Prior chemotherapy	1.15 (0.56-2.68)	0.07
Hypertension	1.08 (0.25-2.64)	0.28
Insulin	1.27 (0.64-3.21)	0.54
Obesity	1.09 (0.57-2.95)	0.13

CI: Confidence interval.