Testosterone therapy in females is not associated with increased cardiovascular or breast cancer risk: a claims database analysis

Background: Testosterone therapy (TTh) has been shown to improve libido in women with sexual dysfunction, but its utilization has been limited due to concern for cardiovascular events and past studies reporting highly variable results. Aim: To assess the association of TTh in women with major adverse cardiac events (MACEs), including heart attack, stroke, or death, using a large database. Methods: The TriNetX Diamond Network was queried from 2009 to 2022. Our study cohort included adult females with ≥3 systemic testosterone prescriptions within a year. Our control cohort excluded females with any testosterone prescriptions, polycystic ovary syndrome, or androgen excess. Both cohorts excluded females with prior heart failure, unstable angina, intersex surgery (female to male), personal history of sex reassignment, or gender identity disorders. Propensity matching between the cohorts was performed. A subanalysis by age was conducted (18-55 and >55 years). Outcomes: We evaluated the association of TTh to the following: MACE, upper or lower emboli or deep vein thrombosis (DVT), pulmonary embolism (PE), breast neoplasm, and hirsutism within 3 years of TTh. Results: When compared with propensity-matched controls, adult females with TTh had a lower risk of MACE (risk ratio [RR], 0.64; 95% CI, 0.51-0.81), DVT (RR, 0.61; 95% CI, 0.42-0.90), PE (RR, 0.48; 95% CI, 0.28-0.82), and malignant breast neoplasm (RR, 0.48; 95% CI, 0.37-0.62). Similarly, females aged 18 to 55 years with TTh had a lower risk of MACE (RR, 0.49; 95% CI, 0.28-0.85) and DVT (RR, 0.48; 95% CI, 0.25-0.93) and a similar risk of malignant breast neoplasm (RR, 0.62; 95% CI, 0.34-1.12). Females aged ≥56 years with TTh had a similar risk of MACE (RR, 0.84; 95% CI, 0.64-1.10), DVT (RR, 0.82; 95% CI, 0.50-1.36), and PE (RR, 0.52; 95% CI, 0.26-1.05) and a significantly lower risk of malignant breast neoplasm (RR, 0.51; 95% CI, 0.38-0.68). Risk of hirsutism was consistently higher in those with TTh as compared with propensity-matched controls. Clinical Implications: Our results contribute to safety data on TTh, a therapy for sexual dysfunction in women. Strengths and Limitations: The TriNetX Diamond Network allows for significant generalizability but has insufficient information for some factors. Conclusions: We found a decreased risk of MACE among women with TTh as compared with matched controls and a similar risk of MACE in postmenopausal women while demonstrating a similar or significantly lower risk of breast cancer on age-based subanalysis.