SLE disease per se contributes to deterioration in bone mineral density, microstructure and bone strength.

Objective: The objective of this report is to assess the effect of systemic lupus erythematosus (SLE) disease itself on deterioration of bone mineral density (BMD), microstructure and bone strength.

Method: Thirty age-matched SLE patients on long-term glucocorticoids (GC) (SLE/GC), 30 SLE patients without GC (SLE/non-GC) and 60 healthy controls were examined. Areal BMD (aBMD) was measured by dual-energy X-ray absorptiometry. Bone geometry, volumetric BMD (vBMD), and architectural parameters at the nondominant distal radius were assessed by high-resolution peripheral quantitative computed tomography (HR-pQCT). Bone strength was estimated by HR-pQCT-based micro-finite element analysis.

Results: Adjusted for menopausal status and adjusted calcium level, when compared with controls, SLE/non-GC patients had significantly lower aBMD at femoral neck and total hip, and diminished radial total vBMD, cortical area, vBMD and thickness, respectively, by 8.3%, 8%, 2.7% and 9.2%, as well as significant compromised bone strength (stiffness, failure load and apparent modulus) by 8.3%, 9.1% and 9.5%, respectively. Similar alterations were also found in SLE/GC patients when compared to controls. In the premenopausal subgroup analysis, when compared with controls, total hip aBMD and radial cortical area were significantly lower in SLE/non-GC patients, and cortical area and thickness were significantly deficit in SLE/GC patients. However, no significant difference in any bone variables was present between SLE/GC and SLE/non-GC patients in the entire cohort or in the premenopausal subgroup.

Conclusion: SLE disease per se contributes to the deterioration in bone density, cortical microstructure and bone strength. This might help to explain the considerably higher fracture risk seen in SLE patients.