Conventional synthetic disease-modifying antirheumatic drugs and bone mineral density in rheumatoid arthritis patients with osteoporosis: possible beneficial effect of leflunomide.

To investigate the effect of conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs) on bone mineral density (BMD) in rheumatoid arthritis (RA) patients with osteoporosis.Patients with RA who were newly diagnosed with osteoporosis (T-score ≤ -2.5) between 2010 and 2017 were included. All patients received background bisphosphonate for treatment of osteoporosis. BMD was measured at baseline and after one year. To identify csDMARDs or other factors associated with significant increase in BMD (≥3%) at lumbar spine and femoral neck at one year, we performed logistic regression analysis. To exclude the possibility of confounding by methotrexate, which was commonly used as a combination therapy with other csDMARDs, we also performed logistic regression analysis in the methotrexate users (subgroup analysis).In total, 153 RA patients with newly diagnosed osteoporosis were included. Leflunomide was the only csDMARD associated with significant increase in lumbar spine BMD (adjusted odds ratio (OR) 3.000, 95% confidence interval (CI) 1.177-7.645, p=0.021). In regard to femoral neck BMD, no csDMARDs were associated with significant increase in BMD. In the subgroup analysis, use of leflunomide was still associated with significant increase in lumbar spine BMD (adjusted OR 2.653, 95% CI 1.030-6.836, p=0.043), whereas no csDMARDs were associated with significant increase in femoral neck BMD.Among the csDMARDs, leflunomide can be beneficial in lumbar spine BMD in RA patients with osteoporosis.