Background Low bone mineral density (BMD) is highly prevalent in patients with systemic lupus erythematosus (SLE). However, determinants of BMD changes in SLE are still largely unknown.
Objectives The aim of this study was to describe the clinical characteristics of SLE patients submitted to a dual energy X-ray absorptiometry (DEXA), evaluating the prevalence of osteopenia/osteoporosis and searching for possible predictors of bone loss in these patients.
Methods Retrospective observational study of 160 SLE patients of our Rheumatology department, was performed. Demographic, clinical data and BMD measurements (g/cm2) of the lumbar spine (LS) and total hip (TH) were collected. The DEXA results were classified according to WHO criteria for osteoporosis. Statistical analyses was performed using t-test, Mann-Whitney U-test, and Spearman correlation (SPSS 21.0).
Results Out of 160 SLE patients, 148 (92,5%) were female with a mean age 44,23±12,5 years. The median SLEDAI was 2 [0-23], median SLICC was 0,2 [0-5]. 74 (56%) patients were taking vitamin D supplements, 56 (35%) were taking calcium supplements and 24 (15%) received bisphosphonate therapy.
Only 81 (50,6%) had a DEXA done. Patients with DEXA were older (47.28±12.7 vs 41.09±11.8 years, p<0.01), had a longer disease duration (13.8±9 vs. 10.6±8 years, p=0.02), high SLICC score (2,0 vs 0,0 p=0,04) and were taking a higher dose of steroids (7 vs 5; p=0,01). No significant differences were found between gender, SLEDAI, serum vitamin D, complement levels, erythrocyte sedimentation rate or c-reactive protein.
Of the 81 patients with DEXA, 34 (42%) had osteopenia, 13 (16%) had osteoporosis and 34 (42%) had normal BMD. The mean lumbar spine BMD was 0.96±0.12 g/cm2 and the mean total hip BMD was 0.87±0.13 g/cm2.
Statistically significantly correlation was found between age and lumbar spine BMD (r=-0,256; p=0,02), age and total hip BMD (r=-0,262; p=0,02), SLICC score and lumbar spine DMO (r=-0,230; p=0,04) and SLICC score and total hip BMD (r=-0,279; p=0,04).
Conclusions In our cohort, SLE patients referred for a DEXA have more traditional risk factors, take a higher dose of corticosteroids and have a higher disease damage access by SLICC score. The prevalence of osteopenia and osteoporosis in our SLE-patients was greater than in general population. In addition to age, disease damage access by SLICC score was associated with low BMD.
Disclosure of Interest None declared