EP862 - Early Experience in Apixaban vs Enoxaparin in Prevention of Postoperative Venous Thromboembolism

Purpose/Background: Patients who undergo major colorectal surgery are at a high risk of postoperative venous thromboembolism (VTE). Specific pathologies, such as malignancy and inflammatory bowel disease (IBD), further increase this risk. Current recommendations are to stratify patients using risk calculators and prescribe 4-weeks of postoperative VTE chemoprophylaxis for high-risk patients. Most clinical practices utilize low molecular weight heparin (LMWH) as the choice agent. However, emerging evidence suggests direct oral anticoagulants (DOACs) are safe and effective in preventing postoperative VTE. In the current study, we compare Apixaban (APX) to Enoxaparin (EPX) in the prevention of postoperative VTE following colorectal surgery.

Methods/Interventions: This is a single institution study involving patients undergoing colorectal surgery between the years 11/2023-12/2026. All patients received subcutaneously injected heparin (SQH) at time of surgery and during hospital admission. At discharge, patients were scored on our modified Caprini score and scores >= 9 are prescribed VTE chemoprophylaxis. Prior to 7/1/2025, patients received subcutaneously injected EPX (40mg per day) for a total of 28 days from surgery. Following 7/1/2025, patients received APX (2.5mg twice a day) for 30 days. All patients were followed up in clinic at a minimum of 30 days after surgery. Baseline characteristics were obtained for all study participants. The primary outcome was VTE development within the first 30 days after surgery with secondary outcomes including postoperative bleeding events, compliance rates, readmissions, and medication associated morbidity and mortality.

Results/Outcomes: The study cohort included 368 participants, 322 were reviewed prior to and 46 were reviewed following protocol initiation. The average age of the cohort was 61 years old (Standard Deviation (SD) 14); low to moderate risk patients were younger at 59 years old (SD 14) whereas high risk patients tend to be older at 66 years old (SD 12). Majority of the cohort was female (217/59%) and Caucasian (236/64%). The most common indication for colorectal surgery involved a benign disease process (202/55%), although colorectal cancer was the most common indication for surgery among high-risk patients (94/75%). 243 patients were deemed low to moderate risk for postoperative VTE and 125 patients met criteria as high risk for postoperative VTE. Of the high-risk patients, 82 received EPX, 12 received APX, and 10 did not receive chemoprophylaxis. 3 patients who did not receive chemoprophylaxis experienced VTE (2 high risk pre-protocol, 1 moderate risk post-protocol) and were re-admitted for work up and management. 7 patients experienced postoperative bleeding (4 moderate risk without VTE prophylaxis, 2 high risk on EPX, 1 high risk on APX), of which 5 were readmitted for observation.

Conclusion/Discussion: This is a preliminary report on the early experience of using APX vs EPX as postoperative VTE prophylaxis in our high-risk colorectal patient population. APX appears to have similar efficacy and safety compared to EPX in preventing VTE, although additional analysis is required to assess statistical associations. Future direction aims include completion of a non-inferiority study design trial.

Figure 1: Treatment Pathway for VTE prophylaxis
Pathway for evaluating individual patient VTE risk. Includes the modified Caprini score utilized in determining VTE risk as well as recommended treatment based on individual patient score.
Table 1: Combined Demographics and Early Outcomes
Demographic and early outcomes of the cohort with further separation between low-moderate and high risk patients. Age and Length of Stay are averaged with associated standard deviation (SD).