Effect of TNF inhibitors on bone mineral density in rheumatoid arthritis patients receiving bisphosphonate: a retrospective cohort study

We aimed to determine whether tumor necrosis factor inhibitors (TNFi) have beneficial effects on bone mineral density (BMD) in rheumatoid arthritis (RA) patients with osteoporosis receiving bisphosphonate. A total of 199 RA patients, who were newly diagnosed with osteoporosis and receiving bisphosphonate between January 2005 and March 2017, were reviewed. Changes in BMD after 1 year were compared between patients treated with and without TNFi. The inverse probability of treatment weighting (IPTW) method using the propensity score was performed to minimize confounding factors, and logistic regression analysis was applied to identify any factors associated with significant BMD improvement (≥ 3%) at the lumbar spine and femur neck. Among patients receiving bisphosphonate, 29 were exposed to TNFi, and 170 patients were not exposed. The percentage change in BMD and the proportion of significant improvements at the lumbar spine and femur neck were similar between patients treated with and without TNFi, before and after IPTW adjustment. In addition, the disease activity score 28 (DAS28) with three variables [adjusted odds ratio (OR) 0.741, 95% confidence interval (CI) 0.592–0.927, p = 0.009] and cumulative steroid dose (adjusted OR 0.639, 95% CI 0.480–0.851, p = 0.002) were inversely associated with an improvement in BMD. Conversely, TNFi use was not associated with any improvement in BMD after adjustment by IPTW using the propensity score. TNFi did not influence BMD improvement in RA patients with osteoporosis receiving bisphosphonate, suggesting that TNFi cannot be considered as a preferred therapeutic option for increasing BMD.