Bisphosphonates and the Risk of Fractures : Survival Analysis Using Patient Data from Swedish National Registers

Sammanfattning: Background Osteoporosis increases the risk of fractures. Bisphosphonates is a group of medications used to treat osteoporosis. Purpose The purpose of this study was to answer the questions: Do bisphosphonates decrease the risk of fractures? Are the effects ofbisphosphonates different depending on a patient’s age or sex? Methods Data were collected for patients in the Swedish National Patient Register who got a fracture between 2006 and 2012 and who were at least fifty years of age. Kaplan-Meier curves and Cox regression were used; both were extended for time-varying covariates and multiple events. Results A patient who had received a bisphosphonate by any given time had an estimated 45.1 % (hazard ratio, .549; 95 % confidence interval, .524-.574) lower rate of fractures than did a patient who would later receive treatment, given that they were the same age when they entered the study. The effect of bisphosphonate treatment did not vary significantly depending on a patient’s age at study entry (p = .866). A patient’s sex had no significant effect on the rate of fractures after adjusting for his/her age at study entry (p = .142). Discussion It is likely that the patients who received a bisphosphonate suffered osteoporosis to a greater extent than did others. If this had not been taken into account the results would have shown that bisphosphonates were associated with an increased rate of fractures.