Background: Patients undergoing colorectal surgery are at increased risk for post-operative venous thromboembolism (VTE). Clinical guidelines strongly recommend VTE prophylaxis for those undergoing resection for colorectal cancer, and weakly recommend the same for those undergoing resection for inflammatory bowel disease (IBD). Apixaban is currently recommended for post-operative VTE prophylaxis in the orthopedic and OBGYN literature, but has not been evaluated in colorectal surgery patients, despite the obvious advantages of oral VTE prophylaxis. Here, we employ an insurance claims database, TriNetX, to compare rates of VTE in patients with IBD undergoing colorectal surgery with the hypothesis that apixaban and enoxaparin will be equally effective in preventing post-operative VTE.

Methods: TriNetX was queried for CPT codes corresponding to colorectal surgeries in those with a diagnosis of ulcerative colitis or Crohn’s disease. Patients who had used any anticoagulant, including anti-Xa medications, enoxaparin, and coumadin within 3 to 1 months prior to index procedure were excluded, 1 month was allowed for those who might have gotten VTE prophylaxis while admitted pre-operatively. Those with an outpatient claim for apixaban or enoxaparin 30 days following surgery defined the apixaban and enoxaparin cohorts respectively. After propensity matching for age, sex, race, ethnicity, and presence of colorectal, or GI-malignancy, risk ratio was computed for rates of VTE within 90 days of surgery, patients with the outcome of interest before this window were excluded. All statistical testing was completed using internal TriNetX software.

Results: The apixaban cohort included 334 patients, while the enoxaparin group included 7,285. The patients in the apixaban cohort were more likely to be female (55.9% vs 50.1%, p = 0.03) and Asian (2.9% vs 1.4%, p = 0.02). After propensity matching, 312 patients were included in the apixaban cohort, while 293 were included in the enoxaparin group. Comparing matched cohorts, 3.2% of the apixaban and 3.4% of the enoxaparin group experienced the outcome of interest. Those in the apixaban cohort had a 0.939 risk of VTE compared to the enoxaparin group, (95%CI = 0.397-2.22, p = 0.8864).

Conclusions: In IBD patients undergoing colorectal surgery, we find comparable rates of post-operative VTE in those who used either apixaban and enoxaparin, though use of apixaban remains comparatively uncommon. Given these data, the obvious advantages of an oral VTE prophylaxis strategy warrant further exploration in this patient population.

Alicia Greene

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