Association of Bisphosphonate Therapy With Incident of Lower Extremity Fractures in Persons With Spinal Cord Injuries or Disorders

Abstract

ObjectiveTo investigate the association between prescriptions for bisphosphonates; calcium and vitamin D supplements; and receipt of dual-energy x-ray absorptiometry (DXA) screening, and incident fracture risk in men and women with a spinal cord injury (SCI) or disorder (SCID). DesignPropensity-matched case-control analyses. SettingUnited States Veterans Affairs (VA) facilities. ParticipantsA total of 7989 men and 849 women with an SCID included in VA administrative databases between October 1, 2005 and October 1, 2015 were identified (N=8838). Cases included 267 men and 59 women with a bisphosphonate prescription propensity matched with up to 4 controls. InterventionsNot applicable. Main Outcome MeasuresIncident lower extremity fractures. ResultsThere was no significant association between prescriptions for bisphosphonates and incident lower extremity fractures in men (odds ratio [OR], 1.04; 95% confidence interval [CI], 0.62-1.77) or women (OR, 1.02; 95% CI, 0.28-3.75). In men, similar null associations were seen among those who were adherent to bisphosphonate therapy (OR, 1.25; 95% CI, 0.73-2.16), were concomitant users of vitamin D and calcium and a bisphosphonate (OR, 1.05; 95% CI, 0.57-1.96), had more than 1 fracture on different dates during the study period (OR, 0.13; 95% CI, 0.02-1.16) and in those who had undergone DXA testing prior to the date of the bisphosphonate prescription and incident fracture (OR, 1.26; 95% CI, 0.69-2.32). ConclusionsIn men with a traumatic SCI and women with a traumatic SCID, bisphosphonate therapies for osteoporosis do not appear to significantly affect fracture risk. Adequately powered randomized controlled trials are needed to definitively demonstrate efficacy of bisphosphonates for fracture prevention in this population. There is a compelling need to identify new medications to prevent fractures in this high-risk population.