GLUCOCORTICOID-INDUCED BONE LOSS IS ASSOCIATED WITH ABNORMAL INTRA-VERTEBRAL BONE DISTRIBUTION: A CLINICAL STUDY

Presentation Number: SAT-263
Date of Presentation: June 15th, 2013

JOHN DENNIS Wark*1, Louise I Manning2, Andrew M Briggs3, Sharon VAN Doornum2, Ashwini Kale1 and Susan Kantor2
1The University of Melbourne / Royal Melbourne Hospital, PARKVILLE, Australia, 2The University of Melburne / Royal Melbourne Hospital, PARKVILLE, Australia, 3Curtin Health Innovation Research Institute,, Perth, Australia

Abstract

Individuals with glucocorticoid-induced osteoporosis experience vertebral fractures at an increased rate and at higher vertebral areal bone mineral density (aBMD) than individuals with primary osteoporosis. Postero-anterior (PA) projection dual energy x-ray absorptiometry (DXA) traditionally lacks the diagnostic sensitivity required for reliable estimation of vertebral fracture risk in individuals with osteoporosis. We postulated that assessment of subregional vertebral aBMD using lateral-projection DXA may improve the predictive value of DXA parameters for fracture. 104 individuals were recruited into 3 groups: primary osteoporosis with no prevalent vertebral fracture (n=43), glucocorticoid-induced bone loss with no prevalent vertebral fracture [glucocorticoid use  ≥5 mg/day of prednisolone or equivalent continuously for ≥ 6 months within the past 3 years together with a diagnosis of either osteoporosis or osteopenia (n=13)], and healthy controls (n=48). PA lumbar spine T scores [mean (95% CI)] were -2.6 (-2.9 to -2.4), -1.6 (-2.4 to -0.9) and 0.0 (-0.2 to 0.3), respectively. Standard PA-projection and supine-lateral scans were performed (Hologic 4500A, software version 9.10D), and lateral scans analysed according to an established protocol (Briggs et al, J Clin Densitom 2005) to measure aBMD within 6 subregions of the vertebral body. Main effects for subregion and group were assessed by ANCOVA, adjusting for vertebral area. Ratios of aBMD were calculated between subregions and compared between groups, to avoid the potentially confounding influence of variability in subregional geometry. The anterior subregion of the L3 centrum was reduced in the glucocorticoid and primary osteoporosis groups compared with controls (P < 0.001) and differed significantly  between these 2 groups (0.355 ± 0.148 v 0.416 ± 0.079g/cm2 , mean ± SD, respectively; P = 0.017), a difference not observed at any other subregion. Examining ratios, significantly lower values were observed in the glucocorticoid group for the anterior subregion/ whole vertebral body ratio when compared to both the primary osteoporosis and control groups [0.72 (0.58-0.86, 0.84 (0.81-0.88), 0.83 (0.80-0.86), respectively; mean, 95% CI; P <0.05 for each].

The absolute and relative reduction in anterior subregional aBMD in individuals receiving glucocorticoid therapy may contribute to their increased vertebral fracture risk compared with primary osteoporosis. Large-scale prospective studies are indicated.

 

Nothing to Disclose: JDW, LIM, AMB, SV, AK, SK