Novel risk factors for venous thromboembolism following outpatient or inpatient transurethral resection of bladder tumors: Multivariable stepwise and LASSO regression modeling from us insurance claim database,Nuevos factores de riesgo de tromboembolismo venoso despu{\'e}s de la resecci{\'o}n transuretral de tumor vesical: modelos de regresi{\'o}n multivariable escalonada y LASSO basados en datos de reclamaciones de seguros de EE. UU

Introduction and Objectives: Transurethral resection of the bladder tumor (TURBT) is a standard procedure in bladder cancer (BC), which is associated with low risk of venous thrombo-embolism (VTE). The aim of this study was to find the predictors of postoperative VTE in patients undergoing TURBT for BC. Materials and Methods: In this retrospective cohort analysis, patients aged ≥18 years with BC diagnosis undergoing TURBT were identified in the Merative® Marketscan® Research de-identified databases in 2007-2021. Patients with prior VTE events were excluded. Preoperative diagnostic codes and outpatient prescriptions present in at least 1% of the cohort were recorded (205 variables). Then, logistic regressions were performed including each variable separately, all variables together, as well as variables selected by stepwise and Least Absolute Shrinkage and Selection Operator (LASSO) selection methods. Adjusted odds ratios (aOR) with 95% confidence intervals (CI) were calculated. Results: In total, 132,425 patients were included in this study, with 1,959 (1.5%) individuals diagnosed with postoperative VTE. Various malignant neoplasms diagnosed before BC were significant risk factors of postoperative VTE, with aOR reaching up to 2.26 (95% CI: 1.96-2.61). Another strong predictor of VTE was a diagnosis of nephritis, nephrotic syndrome, and nephrosis (aOR: 1.67; 95% CI: 1.48-1.87 stepwise; aOR: 1.65; 95% CI: 1.46-1.85 LASSO). Also, patients with diseases of the urinary system, non-specific symptoms, diseases of the respiratory system, anemias, and other cardiovascular diseases were associated with increased VTE risk. Regarding drugs, antidiabetic agents and gastrointestinal drugs reduced the probability of VTE. Conclusions: Numerous preoperative factors have influence on the risk of VTE after TURBT. These findings might facilitate the clinical decision about the implementation of thromboprophylaxis in the appropriate patients.