Purpose: Gender-affirming hormonal treatment (HT) in transgender people can influence bone mineral density (BMD). Earlier studies found an increase in BMD in transwomen (male-to-female transgender people), and a maintenance or increase in BMD in transmen (female-to-male transgender people). However, the effects of HT on fracture risk are not known. Therefore we aimed to investigate the fracture incidence in transwomen and transmen using long-term HT and to compare this with an age-matched male and female control population.

Methods: All adult transgender people who started with HT before 2013 in our center were included. This population was linked to a random sample of 5 age-matched control males and 5 age-matched control females. Fracture occurrence in 2013 and 2014 was provided by Statistics Netherlands (CBS), which stores all diagnoses from visits to the hospital emergency rooms nationwide. The occurrence of fractures is expressed as percentages, and relative risks (RR) with 95% confidence intervals (CI) were calculated.

Results: A total of 1,725 transwomen (mean age 50 years, standard deviation (SD) 13 years) who used HT for median 15 years (inter quartile range (IQR) 8 – 23 years) were included. Fractures occurred in 2.5% of the transwomen (n=43), while 1.9% of the age-matched control men (RR 1.33, 95%CI 0.94 – 1.86) and 2.2% of age-matched control women (RR 1.14, 95%CI 0.82 – 1.60) had a fracture. A total of 729 transmen (mean age 44 years, SD 12 years) who used HT for median 14 years (IQR 6 – 23 years) were included. Fractures occurred in 1.4% of the transmen (n=10), while 1.6% of the age-matched control men (RR 0.85, 95%CI 0.43 – 1.66) and 2.0% of age-matched control women (RR 0.69, 95%CI 0.35 – 1.34) had a fracture.

Conclusion: This large population of both transwomen and transmen using long-term HT does not demonstrate an increased fracture risk compared with an age-matched control population. This increases the evidence that HT does not negatively affect bone health.