5511. Relations Between Worsening NAFLD and Bone Mineral Density
Authors * Denotes Presenting Author
  1. Merlin Manogaram; University of Mississippi Medical Center
  2. Elliot Varney; University of Mississippi Medical Center
  3. Aubrey Smyly; University of Mississippi Medical Center
  4. Chanukya Cherukuri; University of Mississippi Medical Center
  5. Jeffrey Roux; University of Mississippi Medical Center
  6. Anna Mccoy; University of Mississippi Medical Center
  7. Candace Howard *; University of Mississippi Medical Center
This study aims to associate worsening degrees of NAFLD and a surrogate marker for bone mineral density.

Materials and Methods:
This retrospective, single-center observational study included 313 patients with a prior diagnosis of NAFLD with noncontrast CT imaging from January 1, 2004, to June 30, 2016. NAFLD clinical index was calculated from serum laboratory values within the 3-month timeline of imaging studies. Trabecular bone attenuation measurements of the L1 and L2 vertebral bodies served as surrogate markers of bone density as validated by multiple prior studies. Attenuation measurements were performed on noncontrast abdominal CT images using a circular Region-of-Interest (ROI) capturing the mean attenuation value of the anterior two-thirds of the vertebral bodies (avoiding endplate changes and the posterior vertebral plexus), the liver, and the spleen. Using a previously established and validated threshold for normal vs. abnormal bone density of 145 HU, linear regression analyses were conducted to determine the associations of L1 and L2 bone attenuation, liver attenuation, spleen attenuation, liver/spleen attenuation ratio, and NAFLD clinical index. Beta weights and odds ratios were calculated in an effort to understand the effects of bone density on NAFLD clinical index.

Trabecular bone attenuation was inversely proportional to NAFLD clinical index at both L1 and L2. For every 1-unit increase in NAFLD clinical index, there was a decrease in trabecular bone attenuation of 5.5 HU at L1 (ß = -5.50; 95% CI: - 8.48 to - 2.53, <em>p</em> < 0.001) and 4.91 HU at L2 (ß = - 4.91; 95% CI: - 7.90 to - 1.92, <em>p</em> = 0.001). Using 145 HU as the attenuation cut point for normal and abnormal bone density, for every 1 unit increase in NAFLD clinical index, there was a 19% increase in the odds of low BMD at L1 and a 21% increased odds of low bone density at L2. When assessing the association between liver and liver/spleen attenuation with bone attenuation, there was statistically significant but of no or minimal clinical significance.

Worsening NAFLD as defined by the NAFLD clinical index correlates with worsening bone attenuation, irrespective of sex, which can be extrapolated to worsening bone density in a diverse NAFLD population given prior associations between bone attenuation and bone density from previously published reports.