Risk of clinical fractures after gonadotropin-releasing hormone agonist therapy for prostate cancer

Purpose: We assessed the relationship between GnRH agonists and the risk of clinical fractures in men with prostate cancer. Materials and Methods: Using a database of medical claims from 16 large American companies we identified a study group of 3,779 men with prostate cancer who received treatment with a GnRH agonist and a control group of 8,341 with prostate cancer who were not treated with a GnRH agonist. Men with I or more medical claims for bone metastases were excluded. The rates of any clinical fracture, hip fracture and vertebral fracture were compared between the groups. Results: The rate of any fracture was 7.91/100 vs 6.55/100 person-years at risk in men who received vs did not receive a GnRH agonist (relative risk 1.21, 95% CI 1.09 to 1.34). The rates of hip fracture (relative risk 1.76, 95% CI 1.33 to 2.33) and vertebral fracture (relative risk 1.18, 95% CI 0.94 to 1.48) were also higher in men who received a GnRH agonist. GnRH agonist treatment was independently associated with fracture risk on multivariate analyses. Conclusions: GnRH agonists increase the risk of clinical fracture in men with prostate cancer.