Risk for Venous Thromboembolism in Transgender Patients Undergoing Cross-Sex Hormone Treatment: A Systematic Review

Feminizing and masculinizing hormone treatments are established components of management in transgender patients. Exogenous hormones have been associated with hemostatic effects, which are well-studied in cis-gender individuals on hormone replacement therapy (HRT). Unfortunately, comprehensive understanding of their effects on venous thromboembolism (VTE) risk in the transgender population is lacking. This manuscript aims to identify the risk of VTE among transgender individuals undergoing cross-sex hormone therapy. A Systematic review of the literature was performed in March 2020 for studies reporting VTE rates in transgender patients undergoing hormone treatment and rates in cis-gender patients on HRT. Data regarding demographics, hormone therapy, and VTE incidence were collected and pooled for analysis. The primary outcome of interest was the development of a VTE event in association with concurrent hormone administration. Overall, 22 studies were included with 11 reporting VTE rates among transgender patients, 6 in cis-female patients, and 5 in cis-male patients. Data from 9,180 transgender patients (6,068 assigned male at birth [AMAB] and 3,112 assigned female at birth [AFAB]) undergoing hormone treatment and 103,713 cis-gender patients (18,748 female and 84,965 male) undergoing HRT were pooled. The incidence of VTE was higher in AMAB patients compared to AFAB patients (42.8 vs 10.8 VTE per 10,000 patient years; P = .02). The rate of VTE incidences in AMAB patients appears similar or higher than the rate demonstrated in cis-females on HRT. VTE incidence in AFAB patients, however, is similar to the published rates in cis-males on HRT. AMAB patients on hormone therapy have higher VTE rates than AFAB patients. AMAB and AFAB patients may have similar VTE incidence to cis-female and cis-male patients on hormone replacement therapy, respectively. This is the first study to aggregate and quantify the development of VTE events in association with hormone therapy in transgender patients. It places these values in the context of rates published in more widely studied populations. It is limited by its retrospective data and heterogenic data. Surgical planning regarding perioperative and postoperative VTE prophylaxis or cessation of hormone therapy should take into account each patient's Caprini risk assessment and the nature of each intervention. Kotamarti VS, Greige N, Heiman AJ, et al. Risk for Venous Thromboembolism in Transgender Patients Undergoing Cross-Se