Development and validation of a prognostic index for fracture risk in older men undergoing prostate cancer treatment

ObjectivesMen treated with androgen deprivation therapy (ADT) or radiation therapy (RT) for prostate cancer have an increased risk for fractures. Given uncertainty as to whether specific clinical factors can identify men at increased risk, we sought to develop a prognostic index for risk of fracture in this population.Materials and methodsWe used the Surveillance, Epidemiology, and End Results-Medicare database to identify men who received ADT or RT after being diagnosed with localized prostate cancer in 2007–2009. Cox proportional hazards models tested the association of potential risk factors with fracture. In a derivation group, hazard ratios were used to assign points for factors independently related to fracture. The prognostic index was then applied to a validation group.ResultsThe sample of 5824 men had a median age of 73.0 years; 82.9% were white and 8.6% had a fracture within 2 years of treatment for prostate cancer. The Cox model identified 8 variables (age, race, hormone treatment, Elixhauser score, anxiety, Parkinson's, fall-inducing medications and disability status) independently associated with fracture. In the derivation cohort, 4.3% of the sample experienced a fracture in the low-risk group, 8.9% in the intermediate group, and 19.2% in the high-risk group (C statistic, 0.749). The index was applied to the validation cohort (C statistic, 0.782).ConclusionThe prognostic index can help to identify patients at increased risk for fracture. This underscores the importance of identifying risk factors for fracture, given the substantial variation in fracture risk in men treated with ADT or RT.