Background:Patients with Systemic Lupus Erythematosus (SLE) are at risk of osteoporosis (OP) and fragility fractures (FFx) because of the disease or its treatments. We assessed the prevalence and risk factors for OP in patients with SLE.Objectives:Our objective is to determine the prevalence of bone mineral density (BMD) loss and fracture risk factors in SLE patients undergoing dual-energy X-ray absorptiometry (DXA).Methods:This is a cross sectional study conducted during the year 2020 in the Rheumatology and internal medicine departements in Taher Sfar hospital of Mahdia, Tunisia. We included patients aged ≥18 years with a diagnosis of SLE according to the 1997 ACR or 2012 SLICC criteria. Patients with renal or hepatic osteodystrophy, or receiving bisphosphonates were excluded from the study. The BMD values were measured by DXA. The T-score, Z-scores and BMD of the lumbar spine (LS) and femoral neck (FN) were determined. OP was defined as a value of the T-score less or equal to -2.5 SD for postmenopausal women and men aged more than 50 years old, and Z-scores less or equal to -2 for premenopausal women and men aged less than 50 years old.Results:Forty-six SLE patients were included. The mean age was 47.19±16.45 years [18-85], with a mean disease duration of 2.52±3.46 years [15days-15years]. The mean SLEDAI score was 5.34±4.82. As regards menstrual history of female patients: 56.5% were premenopausal, 43.5% were post-menopausal and 6% had premature menopause. 13% of our patients gave history of smoking. The mean BMI was 27.6 ± 6 kg/m2 [15-39.8]. FFx were diagnosed in 4 patients (9%) and the mean age of the first fracture was 45years. GCs were used in 65.2% of cases (30 patients). The mean daily dose of GCs was 10 mg/day and the mean cumulative dose was 20g. Calcium and Vitamin D intake was mentioned in 65.2% of cases (30 patients). The association of SLE with other rheumatic diseases was found in 14 of patients. The mean T-score at FN and LS were respectively 0.02±1.17 and -1.32±1.36. The mean Z-score at FN and LS were respectively 0.53±1.14 and -0.6±1.26. It was found that 17 patients (37% of cases) had OP, 12 had osteopenia (26%) and 17 patients (37%) had normal BMD. 37% of patients had OP at LS, 23.9% osteopenia at LS, 6.5% OP at FN and 21.7% osteopenia at FN. Low BMD was significantly correlated with increased age (p=0.01) and disease duration(p=0.05),post-menopausal status(p=0.04), higher BMI (p=0.004), musculoskeletal involvement (p=0.01), association to other rheumatic diseases (p=0.01), higher disease activity by SLEDAI score (p=0.05), higher Erythrocyte sedimentation Rate (p=0.01) and C-Reactive Protein (p=0.007), low serum complement C3 (p=0.009) and C4 (p=0.04) and cumulative doses of GCs (p=0.01).We found also that BMD at LS was mostly affected by GCs intake, BMI and CRP while BMD at FN was mostly affected by SLEDAI score, C3 and C4 (p<0.001 in all cases). Gender, history of smoking and cardiovascular comorbidities had no significant impact on BMD.Conclusion:OP is a common but unrecognised complication of SLE with increased frequency of both peripheral and vertebral FFx. Our study suggests a high risk profile for OP and FFx in SLE which seems to be associated with age, disease duration, post-menopausal status, BMI and GCs.References:[1]Dey, M., & Bukhari, M. (2018). Predictors of fracture risk in patients with systemic lupus erythematosus. Lupus, 27(9), 1547–1551.Disclosure of Interests:None declared
