To compare the venous thromboembolism (VTE) rate in patients with ovarian cancer undergoing neoadjuvant chemotherapy before and after implementing routine thromboprophylaxis.

This is a quasi-experimental pre-post study evaluating the VTE rate in patients with ovarian cancer who received neoadjuvant chemotherapy following a quality improvement initiative of routine thromboprophylaxis within a single healthcare system that started in January 2017. Patients were excluded if VTE was diagnosed before initiating chemotherapy. Patient factors and perioperative variables of interest were investigated for their association with VTE through univariate and multivariate models.

Of the 136 patients in the pre-implementation group, 3.7% (n = 5) received thromboprophylaxis. Of the 154 patients in the post-implementation group, 65.6% (n = 101) received thromboprophylaxis. Provider compliance varied from 51% in 2019 to 79.3% in 2021. The overall rate of VTE, from the start of chemotherapy to the end of treatment, was 21.3% (n = 29) pre- and 8.4% (n = 13) in the post-implementation group (p < 0.01). There was no difference in major bleeding events between groups (0% vs. 0.68%, p = 0.63). On univariate analysis, thromboprophylaxis (OR 0.19; 95% CI 0.07-0.52) and post-implementation period (OR 0.34; 95% CI 0.17-0.69) were associated with a decreased risk of any VTE during primary treatment. On multivariate analysis, only thromboprophylaxis remained significantly associated with reduced VTE rates (aOR 0.19; 95% CI 0.07-0.53).

Routine thromboprophylaxis during neoadjuvant chemotherapy is associated with reduced risk of VTE throughout primary treatment and is not associated with increased bleeding events.