How Much Do We Need to Worry About Venous Thromboembolism After Hospital Discharge? A Study of Colorectal Surgery Patients Using the National Surgical Quality Improvement Program Database

PURPOSE: It is well recognized that the increased risk of a postoperative venous thrombotic event extends beyond the inpatient treatment period. The purpose of this study was to determine the 30-day incidence and risk factors associated with the occurrence of early postdischarge symptomatic venous thromboembolic events in patients who have undergone major colorectal surgery. METHODS: The National Surgical Quality Improvement Program database was queried for patients who had undergone a colon or rectal resection during the study period (2005-2008). Patient demographics, preoperative risk factors, and operative variables were recorded. The primary outcomes were occurrence of deep venous thrombosis requiring therapy or pulmonary embolism within 30 days after initial surgery. The occurrence of postdischarge venous thromboembolic events was calculated from the days to primary outcome and days from operation to discharge. Univariate and multivariate linear regression models incorporating pre- and intraoperative variables as well as the occurrence of a major or minor complication were used to evaluate the effect of these clinical factors on the early postdischarge venous thromboembolic event rate. RESULTS: A total of 52,555 patients were included in the initial analysis. A total of 240 deep venous thromboses were diagnosed in the postdischarge setting giving a postdischarge incidence of 0.47%. One hundred thirty cases of a pulmonary embolus were diagnosed (0.26% incidence) with 30 patients having a concurrent deep venous thrombosis and pulmonary embolus. The overall cumulative postdischarge symptomatic venous thromboembolic incidence was 0.67% (n = 340). Obesity, preoperative steroid use, "bleeding disorder," ASA class III, and postoperative (major and minor) complications were all independently associated with an increased risk of an early postdischarge venous thromboembolic event. CONCLUSION: This study has identified risk factors that may help stratify patients into different risk profiles and offer prolonged prophylaxis to patients at increased risk on the basis of preoperative risk factors and postoperative complications.