Background: Clinical observational studies revealed that 99Tc-methylene diphosphonate (99Tc-MDP) could reduce joint pain and swollenness in rheumatoid arthritis (RA) patients. This multicenter, randomized, double-blind, double-dummy study aimed to evaluate the effects of 99Tc-MDP plus methotrexate (MTX) vs. MTX alone or 99Tc-MDP alone on disease activity and structural damage in MTX-naïve Chinese patients with moderate to severe RA.
Methods: Eligible patients with moderate to severely active RA were randomized to receive 99Tc-MDP plus MTX (n = 59) vs. MTX (n = 59) alone or 99Tc-MDP (n = 59) alone for 48 weeks from six study sites across four provinces in China. The primary outcomes were the American College of Rheumatology 20% improvement (ACR20) response rates at week 24 and changes in modified total Sharp score at week 48.
Results: At week 24, the proportion of participants achieving ACR20 was significantly higher in the MTX + 99Tc-MDP combination group (69.5%) than that in the MTX group (50.8%) or 99Tc-MDP group (47.5%) (P = 0.03 for MTX + 99Tc-MDP vs. MTX, and MTX + 99Tc-MDP vs.99Tc-MDP, respectively). The participants in the MTX + 99Tc-MDP group and the 99Tc-MDP group had significantly less important radiographic progression than the participants in the MTX group over the 48 weeks (MTX + 99Tc-MDP vs. MTX: P = 0.03, 99Tc-MDP vs. MTX: P = 0.03, respectively). There was no significant difference in terms of adverse events (AEs) among the groups. No serious AEs were observed.
Conclusions: This study demonstrated that the combination of 99Tc-MDP with MTX inhibited structural damage and improved disease activity in RA patients compared with MTX and 99Tc-MDP monotherapies, without increasing the rate of AEs. Additional clinical studies of 99Tc-MDP therapy in patients with RA are warranted.
Trial registration: Chictr.org, ChiCTR-IPR-14005684; http://www.chictr.org.cn/showproj.aspx?proj=10088.
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