Disease Damage Accrual and Low Bone Mineral Density in Female Patients with Systemic Lupus Erythematosus

Osteoporosis is a common comorbidity in patients with systemic lupus erythematosus (SLE), but the potential contribution of disease-associated factors to bone status in SLE is not well known because the reported risk factors from different studies differ greatly. We aimed to examine frequency of reduced bone mass in women with SLE, and determine their potential associations with disease activity, damage accrual and SLE-related clinical markers. A cross-sectional study including 121 Caucasian pre-menopausal and postmenopausal women was conducted (mean age 49.2 ± 12.4 years). The SLE Disease Activity Index (SLEDAI-2 K) and the SDI Damage Index were used to assess disease activity and disease-related damage, respectively. Bone mineral density (BMD) of the left femoral neck and lumbar spine (L2-L4) were measured by dual-energy X-ray absorptiometry. Ten patients (8.3%) had osteoporosis, 63 (52.1%) patients had osteopenia and 6.8% of women had history of previous fracture. Patients with low bone mass had a significantly higher mean SDI (1.3 ± 1.2 versus 0.7 ± 1.0 p = 0.003). T-score at lumbar spine was inversely correlated with SDI score (r = -0.222, p = 0.014) and complement C3 level (r = -0.206, p = .024). SDI scores were significantly different between patients with osteoporosis, osteopenia, and normal BMD after adjusting for covariates (p = .004). There is a high prevalence of low BMD in Caucasian women with SLE, and this status was associated with higher damage accrual scores, supporting that disease damage may itself be a major contributor to the low BMD. Women with SLE with organ damage require regular bone status monitoring to prevent further musculoskeletal damage.