Increased organ damage associated with deterioration in volumetric bone density and bone microarchitecture in patients with systemic lupus erythematosus on longterm glucocorticoid therapy.

Objective: To evaluate bone quality in patients with systemic lupus erythematosus (SLE) who were undergoing longterm glucocorticoid (GC) therapy, and to focus on the correlation between bone quality and organ damage.

Methods: Seventy-eight female patients with SLE and organ damage taking longterm GC, and 72 age-matched SLE patients without damage taking longterm GC were recruited for study. Clinical variables of interest included disease activity, cumulative organ damage (by Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index; SDI), major organ involvement (musculoskeletal damage and neuropsychiatric damage, etc.), and use of medication. Areal bone mineral density (aBMD) was measured by dual-energy X-ray absorptiometry. Bone geometry, volumetric BMD (vBMD), microarchitecture, and biomechanical properties were measured by high-resolution peripheral quantitative computed tomography (HR-pQCT).

Results: Patients were mean age of 45 years (SD 10) and 54% were postmenopausal. The median SDI score of the cohort was 1 (interquartile range 1-2, range 1-5). Compared with patients without damage, the prevalence of osteopenia at either total hip or lumbar spine was significantly higher, and there were trends of deterioration of bone geometry, vBMD, microarchitecture, and biomechanical properties in patients with organ damage. Potential risk factors for bone quality in patients with damage were screened by univariate analysis. During multiple regression analysis, SDI was the only clinical variable consistently associated with deterioration of vBMD and microarchitecture.

Conclusion: Cumulative organ damage consistently correlated with deterioration of vBMD and bone microarchitecture in SLE patients with damage on longterm GC therapy. HR-pQCT provides an insight into the underlying mechanism of bone loss in SLE.