Incidence of Fractures in a Cohort of Veterans With Chronic Multiple Sclerosis or Traumatic Spinal Cord Injury

Abstract

Logan WC Jr, Sloane R, Lyles KW, Goldstein B, Hoenig HM. Incidence of fractures in a cohort of veterans with chronic multiple sclerosis or traumatic spinal cord injury. Objective To measure skeletal fractures in a cohort of veterans with spinal cord dysfunction (SCD) due to multiple sclerosis (MS) or trauma-related spinal cord injury (SCI). Design Retrospective cohort analysis. Setting Database search. Participants Study subjects were a subset of the 1996 Veterans Health Administration (VHA) National Spinal Cord Dysfunction Registry, from which 8150 patients were identified with either MS (n=1789) or SCI (n=6361). Inpatient and outpatient encounters for nonaxial fractures, based on International Classification of Diseases, Ninth Revision, Clinical Modification codes, were identified through VHA administrative databases between October 1996 and June 2005. VHA Beneficiary Identification Records Locator Subsystem death file identified time of death. Interventions Not applicable. Main Outcome Measures Data from the 1996 VHA National Spinal Cord Dysfunction Registry survey was used to determine duration of disease and motor impairment (4 categories of motor impairment based on self-report of the number of limbs involved and degree of motor loss). Proportional hazard modeling evaluated the time to first fracture and Poisson regression evaluated relative risk (RR) of fracture by cause of SCD and degree of motor impairment, adjusting for age, sex, race, and duration of SCD. Results Subjects were, on average, 52.5 years of age, acquired their SCD 22 years prior, and 386 of 8150 were deceased. During the study period, 4021 fracture encounters were identified representing 1738 unique fractures for 1085 of 7832 subjects, for a mean per-person fracture rate of 3.1 per 100 patient-years at risk. The RR of fracture differed according to cause of SCD and motor impairment. Fracture risk was increased by more than 2-fold in those with some motor impairment (RR=2.33, P<.001), by more than 80% with moderate motor impairment (RR=1.87, P<.001), and almost 70% for those with severe motor impairment (RR=1.67, P<.001), compared with those with little motor impairment. Trauma-related SCI increased the RR of fracture 80% (RR=1.82, P<.001) compared with MS. Conclusions Persons with SCD have high rates of skeletal fractures. The highest fracture rates occurred in those with some to moderate motor impairment. There were significant differences in risk of fracture according to causal disease, controlling for motor impairment and duration. There appear to be unique contributors to risk of fracture beyond simply disuse.