Article Title

Incidence of Venous Thromboembolism Following Major Surgery: Opportunities for Care Improvement

Publication Date



venous thromboembolism, surgical outcomes


Background/Aims: Venous thromboembolism (VTE) is an important cause of preventable death and morbidity following major surgery. However, few population-based studies have examined the perioperative incidence of VTE among surgical patients, and most studies limited follow-up to hospital discharge or 1 month following discharge. This study aimed to define the 90-day incidence of VTE in this population, examine trends in incidence over time and identify opportunities for improved use of pharmacological prophylaxis.

Methods: We performed a retrospective cohort study using data from electronic health records of adult patients admitted to one of 14 hospitals in an integrated health system between January 1, 2010, and March 30, 2013, for major nonorthopedic surgery, using relevant International Classification of Disease 9 (ICD-9) procedure codes from the Surgical Care Improvement Project of the Joint Commission. For this analysis, we defined VTE as the presence of a new ICD-9 diagnosis code for pulmonary embolism or deep venous thrombosis, when accompanied by either a pharmacy code for an anticoagulant medication at a dose appropriate for VTE treatment or an ICD-9 procedure code for an objective diagnostic test for VTE. In a prior validation study, this definition had positive and negative predictive values of almost 80%. To capture incident VTE that occurred during hospitalization or within 90 days of discharge, we reviewed inpatient, outpatient, emergency department and claims files.

Results: The sample included 27,723 surgical patients. Patients with VTE were substantially older, had more comorbid conditions and were more likely to be male, non-Hispanic white, widowed and former smokers; 48% of all admissions were related to cancer. The crude risk of VTE was 1.25% over 90 days. The 90-day incidence rate was 15.9 per 100,000 patient-days of follow-up (95% confidence interval: 14.2–17.6). VTE incidence did not vary by calendar year, and relatively small differences were observed across hospitals.

Discussion: The incidence of VTE observed in this study compares favorably to that reported in several prior studies. Next steps include distinguishing preventable VTE from VTE that occurred despite receipt of prophylaxis, and development of risk assessment models to guide rationale use of either pharmacological or mechanical prophylaxis.