Background Abatacept and tocilizumab are representative non-anti-TNF biological DMARDs. However, the direct comparison on the efficacy of these two drugs remains unclear because no randomized controlled trials (RCTs) to compare them have been performed. Although RCTs have brought abundant evidence, the patients in RCTs are limited due to inclusion/exclusion criteria. By the propensity-score matching, potential selection bias can be reduced from population in routine clinical practice.
Objectives To compare the clinical outcomes at 1 year after the treatment with either abatacept or tocilizumab by the propensity-score matching in patients with rheumatoid arthritis (RA) in routine clinical practice.
Methods To overcome potential bias in allocation to the treatment with abatacept and tocilizumab, a propensity-score based on multiple baseline characteristics variables was calculated and 102 from 194 patients treated with abatacept and 102 from 273 patients treated with tocilizumab were statistically extracted by the propensity-score matching. Clinical and functional outcomes at 1 year after the treatment was assessed by the last observation carried forward method.
Results The baseline (BL) characteristics in the extracted abatacept and tocilizumab groups were statistically comparable: mean age 60.7/59.2 years old (abatacept/tocilizumab), disease duration 8.7/9.5 years, prior biologics 45%/40%, concomitant MTX 67%/65%, SDAI 28.7/27.7, HAQ-DI 1.5/1.5, CRP 2.1/2.0 mg/dl, ESR 53/21 mm/h, MMP-3 236.0/205.6 ng/ml, and RF 166.3/176.6 U/ml. Thus, patients with high disease activity despite prior biologics and/or MTX were enrolled. At week 52 (W52), 72%/69% of patients (abatacept/tocilizumab) were still maintained treatment and there was no statistical differences by Kaplan-Meier survival curves and the log-rank test. Changes (BL, W24, W52) in SDAI by abatacept and tocilizumab, were 28.7, 13.6, 14.0 and 27.7, 13.4, 12.5, respectively. At W24 and W52, the remission rates for abatacept/tocilizumab were 16%/16% and 18%/20%, respectively. Thus, no statistical difference in clinical efficacy between abatacept and tocilizumab was observed. Changes in HAQ-DI were also statistically comparable between abatacept and tocilizumab, HAQ-DI at BL, W24, W52 was 1.5, 1.2, 1.2 and 1.5, 1.3, 1.2, the functional remission rates (HAQ-DI≤0.5) at W24, W52 was 32%, 36% and 28%, 28%, respectively. However, prognostic factors at BL contributing to SDAI at W52 were different between two groups by multiple regression analysis; higher RF titer and lower SDAI were associated with lower SDAI at W52 in patients treated with abatacept, whereas lower HAQ-DI and biologics-naïve were associated in those with tocilizumab. The BL factors associated with HAQ-DI at W52 were shorter disease duration and BL lower HAQ in both groups.
Conclusions We could first compare patients treated with abatacept or tocilizumab in patients with RA after statistically adjustment for treatment selection bias by the propensity-score matching. Clinical efficacies including SDAI and HAQ-DI were comparable between two treatments in routine clinical practice. However, the predictive factors at BL for SDAI at W52 were different and abatacept appeared to benefit patients with higher RF titers and early induction of tocilizumab is an important factor for good clinical efficacy.
Disclosure of Interest S. Kubo: None declared, S. Nakayamada: None declared, K. Nakano: None declared, S. Hirata Speakers bureau: Abbvie, Bristol-Myers Squibb., S. Fukuyo: None declared, I. Miyagawa: None declared, K. Hanami: None declared, K. Saito: None declared, Y. Tanaka Grant/research support from: Mitsubishi-Tanabe, Chugai, MSD, Astellas, Novartis., Speakers bureau: Abbvie, Chugai, Astellas, Takeda, Santen, Mitsubishi-Tanabe, Pfizer, Janssen, Eisai, Daiichi-Sankyo, UCB, GlaxoSmithKline, Bristol-Myers
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