Predicting short-term thromboembolic risk following Roux-en-Y gastric bypass using supervised machine learning

Table 1 Baseline characteristic and clinical outcomes of included patients

Factor	Value
N	6526
Postoperative VTE within 30 d (%)	49 (0.8)
Age, median (IQR)	44 (36.1, 52.81)
Age > 50 yr (%)	2083 (31.9)
Female gender (%)	5282 (80.9)
Preop GERD requiring medication (%)	2477 (38.0)
Preop history of MI (%)	67 (1.0)
Previous PCI (%)	140 (2.1)
Previous cardiac surgery (%)	48 (0.7)
Preop hypertensive requiring medication (%)	3340 (51.2)
Preop hyperlipidemia (%)	1691 (25.9)
Preop weight closest to bariatric surgery, median (IQR)	287 (256, 329)
Preop BMI closest to bariatric surgery, median (IQR)	47.61 (44.26, 51.75)
Preop vein thrombosis (%)	128 (2.0)
Preop venous stasis (%)	195 (3.0)
Preop requiring or on dialysis (%)	7 (0.1)
Preop renal insufficiency/CKD (%)	56 (0.9)
Preop therapeutic anticoagulation (%)	201 (3.1)
Previous foregut surgery (%)	710 (10.9)
Current smoker within 1 yr (%)	546 (8.4)
Preop history of COPD (%)	126 (1.9)
Preop obstructive sleep apnea	3196 (49.0)
Preop steroid/immunosuppressant use for chronic condition (%)	113 (1.7)
Preop history of IVC filter placement (%)	25 (0.4)
Preop history of DM (%)	2009 (30.8)
Preop albumin (g/dL), median (IQR)	3.9 (3.4, 4.2)
Preop serum creatinine (mg/dL), median (IQR)	0.77 (0.69, 0.85)
Preop hematocrit (%), median (IQR)	40.3 (37.7, 42.8)
Preop hemoglobin A1c > 7%	741 (11.4)

VTE: Venous thromboembolism; Preop: Preoperative; GERD: Gastroesophageal reflux disease; MI: Myocardial infarction; PCI: Primary coronary intervention; CKD: Chronic kidney disease; COPD: Chronic obstructive pulmonary disease; IVC: Inferior vena cava; DM: Diabetes mellitus.

Table 2 The proposed prediction model for 30-d risk of venous thromboembolism in patients undergoing Roux-en-Y gastric bypass

Variables	Regression coefficient	Standard error	t value	P value	95% confidence interval (lower)	95% confidence interval (upper)
Preoperative COPD	2.54	0.49	5.15	0	1.57	3.51
Length of stay	0.08	0.01	6.24	0	0.06	0.11
Deep vein thrombosis history	1.62	0.67	2.42	0.02	0.31	2.92
Hemoglobin A1c level	1.19	0.34	3.47	0	0.52	1.86
History of venous stasis	1.44	0.53	2.7	0.01	0.4	2.48
Preoperative anticoagulation use	1.24	0.63	1.97	0.05	0.01	2.48
Model constant	-5.77	0.28	-20.61	0	-6.32	-5.22

COPD: Chronic obstructive pulmonary disease.