Venous Thromboembolism Chemoprophylaxis Adherence Rates After Major Cancer Surgery

Importance: Venous thromboembolism (VTE) represents a major source of preventable morbidity and mortality and is a leading cause of death in the US after cancer surgery. Previous research demonstrated variability in VTE chemoprophylaxis prescribing, although it is unknown how these rates compare with performance in the Veterans Health Administration (VHA). Objective: To determine VTE rates after cancer surgery, as well as rates of inpatient and outpatient (posthospital discharge) chemoprophylaxis adherence within the VHA. Design, Setting, and Participants: This retrospective cohort study within 101 hospitals of the VHA health system included patients aged 41 years or older without preexisting bleeding disorders or anticoagulation usage who underwent surgical treatment for cancer with general surgery, thoracic surgery, or urology between January 1, 2015, and December 31, 2022. The VHA Corporate Data Warehouse, Pharmacy Benefits Management database, and the Veterans Affairs Surgical Quality Improvement Program database were used to identify eligible patients. Data analysis was conducted between January 2022 and July 2023. Exposures: Inpatient surgery for cancer with general surgery, thoracic surgery, or urology. Main Outcomes and Measures: Rates of postoperative VTE events within 30 days of surgery and VTE chemoprophylaxis adherence were determined. Multivariable Poisson regression was used to determine incidence-rate ratios of inpatient and postdischarge chemoprophylaxis adherence by surgical specialty. Results: Overall, 30 039 veterans (median [IQR] age, 67 [62-71] years; 29 386 men [97.8%]; 7771 African American or Black patients [25.9%]) who underwent surgery for cancer and were at highest risk for VTE were included. The overall postoperative VTE rate was 1.3% (385 patients) with 199 patients (0.7%) receiving a diagnosis during inpatient hospitalization and 186 patients (0.6%) receiving a diagnosis postdischarge. Inpatient chemoprophylaxis was ordered for 24 139 patients (80.4%). Inpatient chemoprophylaxis ordering rates were highest for patients who underwent procedures with general surgery (10 102 of 10 301 patients [98.1%]) and lowest for patients who underwent procedures with urology (11 471 of 17 089 patients [67.1%]). Overall, 3142 patients (10.5%) received postdischarge chemoprophylaxis, with notable variation by specialty. Conclusions and Relevance: These findings indicate the overall VTE rate after cancer surgery within the VHA is low, VHA inpatient chemoprophylaxis rates are high, and postdischarge VTE chemoprophylaxis prescribing is similar to that of non-VHA health systems. Specialty and procedure variation exists for chemoprophylaxis and may be justified given the low risks of overall and postdischarge VTE.