E-Poster Presentation 30th Australian and New Zealand Bone and Mineral Society Annual Scientific Meeting 2020

Skeletal health in patients with traumatic spinal cord injury: a retrospective cross-sectional study from an Australian tertiary centre (#106)

Joshua L Lee 1 2 , Jean Doyle 3 , Maria-Liza Nery 3 , Roderick Clifton-Bligh 3 4 , Lianne Nier 1 4 , Christian Girgis 3 4 5
  1. Royal North Shore Hospital, St Leonards, NSW, Australia
  2. University of Sydney, Sydney, NSW, Australia
  3. Department of Endocrinology and Diabetes, Royal North Shore Hospital, St Leonards, NSW, Australia
  4. Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
  5. Department of Endocrinology and Diabetes, Westmead Hospital, Westmead, NSW, Australia

Objectives:
Traumatic spinal cord injury (tSCI) is associated with reduced bone mineral density from denervation and reduced load-bearing. We aimed to evaluate bone mineral density (BMD) in patients with tSCI, effects of bisphosphonates, and fracture rates by body region.

Methods:
Retrospective cross-sectional study including consecutive patients with BMD imaging at a tertiary hospital in Sydney, Australia from October 2004 to June 2018 was undertaken. Explanatory variable data extracted from electronic medical records; bisphosphonate usage confirmed using clinic data. BMD modelled using multivariate linear regression adjusting for baseline risk factors.

The outcome variable was femoral neck BMD measured in g/cm2. Potential tSCI risk factors adjusted for BMD included bisphosphonate usage, ASIA score, Australian National Sub-acute and Non-acute Patient (AN-SNAP) coding, time since tSCI. Other adjusted explanatory variables included age, sex, smoking, alcohol, fractures by location, renal/bladder calculi, osteoarthritis.

Multivariable analysis performed using backwards elimination method and χ2 likelihood ratio test. Absolute reduction in BMD with 95% confidence intervals reported using alpha of 0.05.

Results:
60 participants with tSCI were included. After multivariable analysis, BMI, bisphosphonate use, alcohol, ASIA, AN-SNAP, previous fracture location, were significantly associated with BMD. Previous bisphosphonate use compared to no previous antiresorptive treatment was associated with 0.21g/cm2 lower BMD (p=0.0004). ASIA score A had 0.03g/cm2 lower BMD than D (p=0.02). Worse AN-SNAP impairment was associated with lower BMD (C1-C4 0.19g/cm2 lower than incomplete paraplegia, p=0.01), lower BMI (0.02g/cm2 lower per unit, p<0.0001), and alcohol use (0.40g/cm2 lower if ≥2 standard drinks daily, p<0.0001). Fractures were associated with lower BMD – particularly axial/upper limb and knee fractures (0.27 and 0.29g/cm2 lower, p=0.0003).

Conclusions:
Bisphosphonates were used in tSCI patients with statistically lower femoral neck BMD. Independent risk factors for lower BMD in tSCI were ASIA, AN-SNAP coding, lower BMI, alcohol use. BMD was associated with fractures in tSCI patients, despite adjustment for bisphosphonate treatment.

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