Venous Thromboembolism in Transgender Individuals Receiving Hormone Replacement Therapy in Alberta, Canada

Background:

Hormone therapy is a key component of gender-affirming care for transgender individuals. Estrogen, testosterone, and progestin therapy have been associated with a higher risk of venous thromboembolism (VTE). However, this is largely based on use of these medications in hypogonadism, birth control, and hormone replacement therapy (HRT). There is a lack of information regarding their relation to VTE risk in transgender persons. The aim of this study is to retrospectively examine VTE events for transgender individuals in Alberta, Canada, and their potential association with hormone therapy.

Methods:

Chart review of adult (≥ 18 years of age) transgender individuals was completed using electronic medical records between 2002 and 2021. A list of individuals for the study was provided by a psychiatrist who specializes in transgender care at the Gender Program in Edmonton, Canada. Population included those who were referred for gender affirming surgery. Data collected included age, affirmed gender, VTE events, thrombophilia history, anticoagulation use, and hormone therapy. All data was anonymized prior to analysis. This study was approved by the Alberta Health Ethics Research Board (Pro00114160).

Results:

Fifty-six individuals were identified for this study. Median age as of December 31, 2021 was 27.5 years (range 18-73). Affirmed gender in this cohort included 36 affirmed females (64%), 13 affirmed males (23%), and 7 non-binary individuals (13%). None of the individuals had a history of thrombotic events prior to the study, nor did any have known genetic or acquired thrombophilia. Two of the affirmed female individuals (ages 69 and 73) were on anticoagulation for atrial fibrillation during the study. There were no VTE events (DVT or PE) documented in this cohort.

In terms of HRT, 46 of 56 individuals (82%) were on HRT at some point in the study, including 32/36 affirmed females (89%), 10/13 affirmed males (77%), and 4/7 non-binary individuals (57%). 18/36 of affirmed females (50%) were on combined estradiol and progesterone at some point in the study.

Limitations of this study include the small numbers, retrospective nature and incomplete documentation. Furthermore, transgender individuals must go out of province for gender affirming surgery, and documentation around this strong provoking event was not included as was not accessible in this chart review.

Conclusion:

While there is a known association between hormone supplementation and VTE, there were no documented VTE events in this cohort. Further prospective studies would be ideal to fully characterize other VTE risk factors in this cohort and to monitor for VTE events.

Wu:BMS-Pfizer: Honoraria, Research Funding; Pfizer, Leo Pharma, Servier: Honoraria; Bayer: Research Funding.