Objectives To evaluate the trabecular bone score (TBS) in patients with systemic lupus erythematosus (SLE).
Methods Design: Cross sectional study. Patients: we recruited 37 patients with SLE who had at least one DXA and one analysis of the trabecular microarchitecture during the follow-up. Protocol: we analysed the most recent DXA, TBS and clinical data collected from the clinical records using a predesigned questionnaire. Variables: demographic, therapeutic (including use of glucocorticoids and antiresorptives), clinical and laboratory features of SLE (including cumulative number of ACR criteria of LES, SLICC damage and SELENA-SLEDAI average of the two years prior at protocol date). Also were collected: personal and family history of fragility fractures, densitometric diagnosis (OMS) and FRAX index. Outcome variables: (1) Measurement of microarchitecture using software “Trabecular bone score -MedIMaps®” (TBS) and (2) Measurement of BMD (g/cm2) of the lumbar spine (L1 L4), proximal femur and total hip, using DXA (GE Lunar Prodigy Advance). Definitions: The cutoff points for TBS used in the study were the same proposed by the International working group of TBS users: (1) Normal microarchitecture, score>1.350; (2) microarchitecture partially degraded, score <1.350 and >1.200; and (3) microarchitecture degraded<1.200. Bone densitometry scores were classified according to OMS criteria as normal bone, osteopenia and osteoporosis at the lumbar spine (LS), femoral neck (FN) and total hip (TH). Statistical analysis: Descriptive analysis of the main variables, T-student test for the comparison of quantitative variables of groups, Fisher exact test to compare qualitative and correlation of Pearson/Spearman Rho for the quantitative variables.
Results The main characteristics of the patients (n=37) are shown in the Table. Almost all of them had received hydroxychloroquine, calcium supplements and vitamin D. The majority had lumbar osteopenia (43.9%) and trabecular bone microarchitecture partially degraded (46.3%). A trend towards association between densitometric diagnosis (OMS) and the TBS LS (p=0.096) was observed, but not in the case of the BMD FN (p=0.335) or BMD TH (p=0.447).) A negative correlation between the FRAX index and the LS T-score (p=0005 r= -0.5) and FN (r= -0.7; p<0.001 was observed, but not with the TBS (Rho = -0, 3; p=0.1). No correlation between FRAX, TBS, SLEDAI and SLICC was observed. No association was observed between the uses of hydroxychloroquine, oral or intravenous glucocorticoids and the T-score or TBS.
Conclusions Most patients with SLE studied in this small pilot study have some moderate bone disorder that affects both the amount of bone mass and quality of their lumbar trabecular microarchitecture.
Disclosure of Interest None declared