Incidence of and risk factors for post-operative venous thromboembolism after free flap breast reconstruction in a London teaching hospital: A retrospective cohort study.

[OBJECTIVE] The objective of this study was to determine the incidence of venous thromboembolism (VTE) following autologous breast reconstruction, assess risk factors that may predict incidence and assess the accuracy of the Caprini risk assessment model.

[BACKGROUND] VTE is a rare, but potentially lethal complication of autologous breast reconstruction. An accurate preoperative risk-stratification strategy is essential to improve patient outcomes by determining the patients who would benefit from extended thromboprophylaxis after surgery.

[METHODS] Patients who underwent autologous free flap breast reconstruction at a London teaching hospital from 2019-2021 were included. Risk factors for VTE were analysed. VTE incidence was assessed, and the risk factors were identified using multivariate analysis.

[RESULTS] Overall, 368 patients were included in the study. Among them, 10 (2.72%) had a confirmed diagnosis of post-operative VTE, at an average of 23 days after surgery (range 3-64 days). All VTEs occurred in deep, inferior epigastric artery perforator flap patients with a history of breast cancer. Multivariate regression analysis revealed a statistically significant correlation between the incidence of VTE and Caprini score (p = 0.030) and length of hospital stay (p = 0.007). Tamoxifen use was individually significant for VTE (p = 0.043) but non-significant (p = 0.106) when confounded for length of hospital stay (LOS) and Caprini score.

[CONCLUSIONS] Current VTE risk assessment tools do not accurately identify patients who are at risk of developing VTE following free flap breast reconstruction. The Caprini risk assessment model and LOS may be useful in predicting post-operative VTE in this cohort. These patients may benefit from extended chemoprophylaxis. Larger prospective studies are required to optimise risk prediction models in this cohort.