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

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.