Effect of Bisphosphonates on Fracture Incidence in Young Adults With Low Bone Density

Abstract

ObjectiveTo assess the effect of bisphosphonates on fracture incidence in young adults over a 5-year follow-up period. MethodsBased on the Kaiser Permanente electronic health record, this retrospective study investigated patients aged 19 to 40 years with abnormal bone density (either any Z-score of ≤−2 standard deviation [SD] or any T-score of ≤−2.5 SD). The incidence and time to fracture between the control (patients with <6 months of bisphosphonate exposure) and treatment (patients with ≥6 months of bisphosphonate use within 4 years of their first dual energy x-ray absorptiometry scan) groups were compared. Comparisons were analyzed with Χ2 test for categorical variables and Wilcoxon rank sum test for continuous variables. ResultsA total of 422 patients met the inclusion and exclusion criteria. Fractures occurred in 18 patients (5.0%) of the control group (n = 358) and 5 patients (7.8%) of the treatment group (n = 64; P = .37). T-scores were significantly lower in the treatment group (−2.53 ± 0.58 SD) than those in the control group (−2.30 ± 0.80 SD; P = .002) but did not correlate with fracture risk. No significant differences were found in total fracture incidence (hazard ratio = 1.54; 95% confidence interval, 0.26-6.26). Similarly, no correlation was noted between the length of bisphosphonate therapy and fracture incidence (odds ratio = 0.99; 95% confidence interval, 0.966-1.026). ConclusionIn summary, we did not find a clear correlation of fracture incidence with the use of bisphosphonates in young adults. Further research into the pathophysiology, specific etiologies, and treatment options in this population is needed.