MP28-07: Association Between Baseline Bone Mineral Density Testing and the Risk of Fractures in Men Initiating Androgen Deprivation Therapy: Population-Based Study

Jason Hu*, Armen Aprikian, Alice Dragomir, Montreal, Canada

Introduction: Androgen deprivation therapy (ADT) is a staple of advanced prostate cancer (PCa) treatment, however several side-effects are associated with its long-term use. Notably, loss of bone mineral density (BMD) is accelerated which increases fracture risk.  Although guidelines recommend BMD testing when initiating ADT to properly assess baseline fracture risk, there is scarce data to support this recommendation in the PCa patient population.  The objective was to examine the association between baseline BMD testing and the risk of fractures in men initiating ADT for PCa.

Methods: The cohort consists of men extracted from Quebec public healthcare insurance administrative databases who were diagnosed with PCa from 2000-2015 and treated by ADT. Only patients who received at least one year of continuous ADT treatment were included. Baseline BMD testing was defined as a BMD test performed from 12 months prior to ADT initiation and up to 3 months after. The primary study outcomes were incidence of any fracture and incidence of fractures resulting in hospitalization.  Inverse probability of treatment weighting was used to control for measured baseline characteristics which included patient demographic variables, comorbidities, risk factors for fractures, use of other medications affecting bone density, and other variables.

Results: We identified 18,365 patients who initiated ADT at a mean age of 75 years old during the study period, of which 2,218 (12.1%) underwent baseline BMD testing.  The unadjusted 5-year incidence of any fracture was 5.7% for patients not receiving baseline BMD and 3.7% for patients receiving baseline BMD testing.  In weighted analyses, baseline BMD testing (hazard ratio [HR] 0.89, 95% confidence interval [CI] 0.68-1.11) was not statistically significantly associated with the risk of fracture. For fractures requiring hospitalization, baseline BMD testing was associated with a lower risk (HR 0.75, 95%CI 0.54-0.98).

Conclusions: In our study population, baseline BMD testing was associated with a lower risk of fractures resulting in hospitalization. Given the low uptake of baseline BMD testing, additional efforts emphasizing the importance of BMD testing in guidelines may be needed.

Source of Funding: Fonds de recherche du Québec - Santé