Retrospective Cohort Study of Venous Thromboembolism Rates in Ambulatory Cancer Patients: Association With Khorana Score and Other Risk Factors

BACKGROUND: Guidelines do not recommend that cancer outpatients receive thromboprophylaxis unless at high venous thromboembolism (VTE) risk, with the Khorana score suggested for risk stratification. This study investigated VTE incidence in outpatients with pancreatic, endometrial, colorectal, ovarian and cervical cancer, the role of Khorana score in risk assessment and potential risk factors. METHODS: Data were retrospectively collected 1 year after cancer diagnosis. VTE associated with inpatient admissions was excluded. RESULTS: Seven hundred forty-six patients were included. VTE rates varied: 26.8% pancreatic; 5.7% endometrial; 9.8% colorectal; 10.2% ovarian; and 0.0% cervical cancer. Excluding VTE at diagnosis, potentially preventable VTE rates were 16.5% in pancreatic, 3.8% in endometrial, 9.8% in colorectal and 8.7% in ovarian cancer. Khorana score was associated with VTE in endometrial cancer only (high-risk: 16.7% vs. low-risk: 1.5%; P < 0.001). VTE rates for patients with central venous catheters (CVCs) were 22.6-34.8% in pancreatic, endometrial, colorectal and ovarian cancers. VTE was associated with CVCs in endometrial, colorectal and ovarian; chemotherapy and Hb < 100 g/L in pancreatic; surgery in endometrial and ovarian; and body mass index > 35 in ovarian cancers following adjusted analysis (P < 0.05). CONCLUSIONS: VTE is a significant burden in pancreatic, endometrial, colorectal and ovarian cancers. Khorana score was not predictive in most cancers. The major VTE-associated variable was CVC. Our data suggest a role for clinical trials of thromboprophylaxis in targeted cancer outpatients.