Retrospective cohort study findings may help guide decision-making in the intersection of dermatologic and gender-affirming care.
Testosterone is a crucial aspect of gender-affirming hormone therapy and can be delivered intramuscularly, subcutaneously, or transdermally.
Each route of administration has pharmacological differences and is associated with a unique risk of acne but less is known about the incidence of acne development between the different formulations.
Now, American researchers have used the TriNetX database to compare the risk of developing acne in transmasculine patients receiving injectable and transdermal testosterone for GAHT.
“Our findings suggest that injectable testosterone is associated with modestly increased acne risk compared with transdermal formulations. Although unlikely to dictate formulation choice, these findings may help inform counseling and shared decision-making incorporating dermatologic and gender-affirming care goals,” they wrote in the Journal of the American Academy of Dermatology.
The database search identified 8482 transmasculine patients (individuals who had been assigned female at birth with a history of sex reassignment or gender dysphoria) over the age of 18 who had initiated at least two prescriptions of either injectable or transdermal testosterone.
People who had previously had acne, were using acne-inducing medications, or had switched between injectable and transdermal testosterone products were excluded. The risk of developing acne was tracked for two years after initiating testosterone.
More of the cohort received injectable testosterone (n = 7290) than a transdermal preparation (n = 1192), but the two groups were reasonably similar with respect to the average age of GAHT initiation (22.3 versus 24.8 years), ethnicity (76.0% White versus 78.7%), smoking status (4.3% versus 2.8%), and BMI (28.5kg/m2 versus 27.6kg/m2).
Acne developed in 9.9% of the injectable testosterone group and 5.6% of the transdermal group. The sharpest increase in acne incidence occurred in the first six months of treatment for the injectable group (4.2%) and the first six to 12 months for the transdermal group (2.6%).
Acne incidence plateaued after the first year of treatment across both groups.
After accounting for age at GAHT initiation, ethnicity, BMI, smoking status, and baseline testosterone levels, acne was more likely in the injectable testosterone group compared to the transdermal group (hazard ratio and 95% confidence interval 1.61, 1.23-2.12). The association remained when propensity score matching was used (HR 1.55, 95% CI 1.14-2.09).
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“The predominance of topical therapies over systemic agents may suggest that most treated cases were mild-to-moderate,” the researchers noted.
“However, treatment patterns alone are insufficient to infer severity, particularly in transmasculine patients with pregnancy potential who must comply with iPLEDGE requirements to access isotretinoin, potentially limiting its use independent of clinical need.”
“Given the moderate absolute risk difference (4.3%), acne risk alone is unlikely to determine formulation choice but may help inform anticipatory counseling regarding expected dermatologic effects,” they concluded.
