Risk factors for fracture among current, persistent users of bisphosphonates.

ABSTRACT

SUMMARY: Bisphosphonate therapy reduces fracture risk but does not eliminate fracture occurrence. We determined the fracture incidence and risk factors for fractures among 14,674 bisphosphonate users in a community setting. Bisphosphonate users remained at risk of fracture, and additional measures to prevent fractures in these patients would be beneficial. INTRODUCTION: Bisphosphonate therapy reduces but does not eliminate fracture occurrence. The incidence of fracture and risk factors for fractures among persistent, current users of bisphosphonates in a community setting have not been well studied. METHODS: We conducted a retrospective cohort study of 14,674 bisphosphonate users in a health maintenance organization. Patients were followed until a 3-month gap in therapy, creating a pool of highly compliant [mean medication possession ratio (MPR) of 94%] current users. We used Cox proportional hazards models to identify risk factors for fractures among these persistent, current users. RESULTS: There were 867 fractures over the period of observation or 3.7 fractures per 100 users per year. Older patients who take multiple medications, have lower bone mineral density, have a history of prior fracture, and suffer from particular comorbidities (i.e., dementia, chronic kidney disease, and rheumatoid arthritis) are at higher risk of fracture while taking bisphosphonates. CONCLUSION: Persistent, current bisphosphonate users remain at risk of fracture, and additional measures to prevent fractures in these patients would be of benefit.