A novel algorithm to reduce VTE in peri-operative patients on tamoxifen

Venous thromboembolism (VTE) is a serious adverse event associated with tamoxifen use, with a 2 to 3-fold increase incidence in users. We aimed to reduce the incidence of venous thromboembolism in patients undergoing breast related surgery by implementing a risk stratifying algorithm for the perioperative management of tamoxifen.

A retrospective control cohort was compared to a prospective interventional cohort to validate the algorithm which was created by a multidisciplinary team. The algorithm classed patients as low, moderate, high, or very high risk, based on patient factors, and then managed their tamoxifen accordingly during the perioperative period. Each case was then analysed for the presence of a symptomatic, diagnosed venous thromboembolic event up to 60 days post operatively.

A total of 446 (n = 446) consecutive patients were analysed between May 2015 and July 2018 with a 3.36% (15/446) incidence of venous thromboembolism. The retrospective arm consisting of 306 cases, not subjected to the algorithm, showed a 4.58% (14/306) event rate while the prospective arm of 140 cases, managed with the algorithm, showed an event rate of 0.71% (1/140). Analysis with Fisher's exact test showed a significant reduction in VTE using the algorithm (p = 0.0447, CI = 0.95). The cessation of tamoxifen was more rationalised (no algorithm-18.1 days, low risk-0.125 days, moderate risk-14.988 days, high risk-29.6 days, very high risk-32.5 days) and stopped for 11.6% fewer days when using the algorithm.

The use of this algorithm significantly reduces the risk of venous thromboembolism in this population while reducing the number of omitted tamoxifen doses.