Background/Purpose: Low bone mineral density (BMD) and osteoporosis may be significant complications in patients with systemic lupus erythematosus (SLE). Recent studies have shown that biologic therapy could arrest general bone loss, however, the role of  rituximab on BMD in SLE patients has not been analyzed. The aim of this prospective study was to assess the effects of rituximab on BMD at the lumbar spine and femoral neck in women with SLE, one year after rituximab therapy.

Methods: Thirty active female SLE patients treated with rituximab were compared with control SLE women not treated with rituximab. In those patients, rituximab 1 g was administered on days 1 and 15 in addition to current immunosuppressive treatment, which was maintained until disease remission. Since all patients were using steroids when rituximab therapy began, they were all taking calcium and vitamin D. Historical controls included forty-six SLE women with similar lupus activity treated with conventional therapy azathoprine, methotrexate, mycophenolate mofetil, leflunomide and cyclophosphamide) without rituximab therapy. BMD at the femoral neck and lumbar spine was measured using dual energy x-ray absorptiometry before initiating conventional and biologic therapy and after one year.

Results: Seventy-six patients were studied. The mean age was 38.5 ± 2.1 SD, median disease duration was 7 years (range 1 to 26). Thirty patients received rituximab and forty- six controls received conventional treatment. Baseline BMD measurements were higher in the rituximab group. In the rituximab group, after 1 year of follow up femoral neck BMD decreased from 0.980 ± 0.130 g/cm2 to 0.809 ± 0.139 g/cm2 (-17.4%; p = 0.001). Similarly, lumbar spine BMD decreased from 1.062 ± 0.137 g/ cm2 to 0.893 ± 0.194 g/ cm2 (-15.8%; p= 0.001). In controls, femoral neck BMD decreased from 0.914 ± 0.193 g/cm2 to 0.890 ± 0.135 g/cm2 (-2.6%; p= 0.001) and lumbar spine BMD decreased from 0.926 ± 0.128 g/cm2 to 0.867 ± 0.139 g/cm2 (- 6.2%; p= 0.09). BMD loss was higher in postmenopausal rituximab patients than in postmenopausal controls (0.324 ± 0.128 g/cm2 vs 0.138 ± 0.099 g/cm2). There was a significant difference in BMD at the femoral neck between responders and nonresponders (p = 0.014) but not in BMD at the lumbar spine.

Conclusion: After one year of follow up, SLE patients had lower BMD at both the femoral neck and lumbar spine, but the loss was greater in patients receiving rituximab than in patients receiving conventional treatment, and in postmenopausal women. Postmenopausal candidates for rituximab should be evaluated closely to prevent further BMD loss.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/bone-mineral-density-in-lupus-erythematosus-women-one-year-after-rituximab-therapy/