Background/Purpose: Biologic agents used in patients with rheumatoid arthritis (RA) have increased in recent years. Abatacept (ABT) has been described as relatively safe for elderly patients because of lower risk of infectious events than other biologic agents. Tocilizumab (TCZ) was approved for marketing for use in patients with RA in Japan ahead of other countries in 2008. Randomized controlled trials have been shown the efficacy and safety of ABT and TCZ in RA patients. It is required to compare biologic agents in real clinical practice. Therefore, we investigated the efficacy, safety, and continuation rate of ABT and TCZ in patients with RA.

Methods: One hundred eighty three patients with RA treated with ABT or TCZ retrospectively observed for 12 months in Saitama Medical University Hospital since 2010 to 2018. We compared the baseline characteristics, disease activity, physical disability, drug continuation rate, and adverse events between the patients treated with ABT and TCZ.

Results: In ABT group (n=85) compared with TCZ group (n=98), we found older age at initiation of biologics (ABT vs. TCZ: 64 vs. 58 years, p=0.011), higher HAQ-DI score (1.5 vs. 1.0, p=0.003), higher titer of rheumatoid factor (318.2 vs. 126.5 IU/mL, p=0.001), and fewer MTX-users (44.7 vs. 62.2%, p=0.025). Disease duration, rate of female, naïve rate of biologics, body weight, DAS28-ESR4, CDAI, MMP-3, the positive rate of rheumatoid factor and anti-CCP antibody, dose of MTX and PSL at baseline were similar between the groups. CDAI and HAQ-DI significantly decreased at one year after initiation compared to baseline in both groups. The patients who achieved remission or low disease activity in CDAI at one year after initiation tended to be lower in ABT group than TCZ group (67.3 vs. 82.4%, p=0.061). There was no significant difference in the drug continuation rate (81.2 vs. 80.6%). In the patients who discontinued ABT or TCZ during one year of observational period, the rate of adverse events (10.6 vs.12.2%) and inefficacy rate (7.1 vs. 5.1%) as reasons for discontinuation were not significantly different between the groups. Infection occurred most commonly as adverse events in both groups (4.7 vs. 7.1%). In ABT group, the rate of PSL-users and daily dose of PSL significantly decreased in one year after initiation compared to those at baseline (69% vs. 60%, P=0.031, 6.4 vs. 6.0mg/day, p=0.002). In TCZ group, the rate of PSL-users and daily dose of PSL significantly decreased one year after initiation (60 vs. 35%, p< 0.001, 5.1 vs. 3.6 mg/day, p=0.003).

Conclusion:

ABT was tended to be selected for patients, who had disadvantageous conditions such as older age, higher HAQ-DI, fewer MTX users at baseline, and ABT-treated patients achieved lower rates of remission or low disease activity one year after initiation compared to TCZ-treated patients. In spite of these different backgrounds of patients, rate of discontinuation for inefficacy, adherence, and safety were equivalent between the two groups.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/efficacy-safety-and-continuation-rate-of-abatacept-and-tocilizumab-in-patients-with-rheumatoid-arthritis-the-comparative-observational-study/