Diagnosis of Venous Thromboembolism as an Outpatient in Patients Undergoing Surgical Treatment for Malignancy: An Analysis of ACS NSQIP Data 2005-2008

Abstract

Introduction: the relationship between malignancy, surgery and venous thromboembolism (VTE) is well established. Previous studies have reported that the incidence of VTE varies by tumor type. Current guidelines provide recommendations on use of inpatient pharmacoprophylaxis for surgical oncology patients. the practice of continuing pharmacoprophylaxis after discharge is reserved for the “high-risk” patient and the use of this practice varies widely. Little is known regarding rates of outpatient VTE diagnosis by tumor site for surgical patients. the current study was designed to determine the likelihood of VTE diagnosis after hospital discharge by site of neoplasm to help inform surgeons when deciding upon the duration of pharmacoprophylaxis for their cancer patients. Methods: We performed a retrospective cohort study of patients entered into the ACS-NSQIP database from 2005-2008 who underwent a surgical procedure and had a post-operative neoplasm diagnosis. The incidence of VTE was calculated by tumor site for malignant neoplasms and the median post-operative day of diagnosis of VTE and median post-operative day of discharge were calculated and compared across cancer types. We report 30-day VTE outcomes and censored length of stay at 30 days. Patients with neoplams in the field of general surgery, gynecologic and genitourinary surgery were analyzed. Patients with VTE diagnosis on the day of discharge were excluded from the analysis of outpatient status (n=13) as well as patients who were missing day of diagnosis of VTE (n=6). For VTE patients, diagnosis status (inpatient versus outpatient) was determined and the percent of VTE patients diagnosed as an outpatient was compared across groups. An incidence of post-discharge VTE diagnosis was determined by multiplying the incidence and the percent of patients with outpatient discharge for each malignancy site. Results: Out of 130,284 patients who underwent surgery for neoplasm, there were 92,072 with malignant diagnosis by pathology, of which 76,479 were included in the analysis. The incidence of VTE varied substantially by site of malignancy (0-51 events per 1000 cases). Percent of VTE events diagnosed as an outpatient varied as well, ranging from 0 to 100% (see Table). The absolute incidence of VTE diagnosed as an outpatient ranged from 0 to 10.1 per 1000 cases, with malignancies of the pancreas, stomach and prostate having the highest rates. Conclusions: Extended VTE pharmacoprophylaxis should be considered for patients with malignancies with a high incidence of VTE diagnosis after discharge, such as malignancies of the pancreas, stomach and prostate. Future studies to determine the impact of extending VTE prophylaxis on rates of VTE and re-admission or complications of bleeding are needed. Table from Abstract 35.7 Site Number of VTE events per 1000 cases Median Post-operative Day of Diagnosis VTE N (min, max) Median Post-operative Day of Discharge N (min, max) Diagnosed as Outpatient (%) Number of VTE events per 1000 cases diagnosed as outpatient Pancreas 33.4 11 (0, 30) 8 (0, 30) 30% 10.1 Stomach 37.6 10 (0, 30) 8 (0, 30) 26% 9.6 Prostate 11.5 9 (1, 30) 1 (0, 30) 80% 9.2 Uterus 18.8 8 (2, 22) 3 (0, 30) 45% 8.5 Cervix 8.5 20 (20) 3 (0, 27) 100% 8.5 Liver 33.0 9 (1, 30) 6 (0, 30) 25% 8.3 Small Intestine 25.2 10 (3, 29) 8 (0, 30) 28% 7.1 Bladder 10.5 10 (1, 20) 1 (0, 30) 67% 7.0 Large Intestine 22.4 8 (0, 30) 6 (0, 30) 31% 7.0 Esophageal 50.7 10 (2, 28) 11 (0, 30) 14% 6.9 Gallbladder 22.7 12 (2, 29) 8 (0, 30) 27% 6.1 Ovarian 35.3 5 (2, 30) 5 (0, 30) 15% 5.4 Rectum 16.7 9.5 (1, 30) 6 (0, 30) 30% 5.0 Breast 2.3 11 (1, 30) 1 (0, 30) 77% 1.8 Thyroid 0.8 8 (4, 29) 1 (0, 30) 100% 0.8 Adrenal 37.0 3 (1, 12) 5 (0, 30) 0% 0.0 Parathyroid 0.0 n/a 1 (0, 20) n/a 0.0 Open table in a new tab