In patients with rheumatoid arthritis (RA), the relative risks (RRs) for serious infections (SIs) vary with treatment course, with tocilizumab having the least, abatacept in the middle, and rituximab the most, according to study results published in the Annals of the Rheumatic Diseases. The results indicated that the incidence rate (IR) of SI varies between the drugs.

The study included participants with RA from Denmark (DANBIO) and Sweden (Anti-Rheumatic Treatment in Sweden Register/Swedish Rheumatology Quality Register) who started abatacept, rituximab, or tocilizumab treatment between 2010 and 2015. The researchers identified the incidence of SIs and potential confounders through linkage to national registries. They calculated age- and gender-adjusted IR of SIs per 100 person-years and in addition adjusted risk ratios (RRs) of SI during 0 to 12 and 0 to 24 months from the start of treatment.

Overall, the researchers identified 8987 treatment courses:


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  • 2725 patients treated with abatacept
  • 3363 patients treated with rituximab
  • 2899 patients treated with tocilizumab 

At baseline, participants treated with rituximab were older, had longer disease duration, and had more previous malignancies compared with the other groups. Conversely, participants treated with tocilizumab had higher C reactive protein levels. During 0 to 12 months of follow-up, the researchers identified 456 SI events; this number rose to 639 during 0 to 24 months of follow-up. After adjusting for age and gender of Danish participants, the researchers found an IR of 7.1 for abatacept, 8.1 for rituximab, and 6.1 for tocilizumab at 12 months; and 6.1, 7.5, and 5.2 at 24 months. In Swedish participants, the IRs were 6.0 for abatacept, 6.4 for rituximab, and 4.7 for tocilizumab at 12 months; and 5.6, 5.8, and 4.3 at 24 months. The researchers found adjusted 12-month RR for tocilizumab vs rituximab of 0.82 (0.50 to 1.36) in Danish participants and 0.76 (0.57 to 1.02) in Swedish participants, for a pooled RR of 0.78 (0.61 to 1.01). For abatacept vs rituximab, the RR was 0.94 (0.55 to 1.60) in Danish participants and 0.86 (0.66 to 1.13) in Swedish participants, with a pooled RR of 0.88 (0.69 to 1.12). For abatacept vs tocilizumab, the RR was 1.15 (0.69 to 1.90) in Danish participants and 1.14 (0.83 to 1.55) in Swedish participants, with a pooled RR of 1.13 (0.91 to 1.42). The adjusted RRs for 0 to 24 months were comparable.

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“The findings should be interpreted with caution due to the few events and the risk of residual confounding, but do not support that one non-TNFi [tumor necrosis factor inhibitor] should be recommended over the other for patients with RA at high risk of SIs,” the researchers wrote.

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Reference

Grøn KL, Arkema EV, Glintborg B, et al. Risk of serious infections in patients with rheumatoid arthritis treated in routine care with abatacept, rituximab and tocilizumab in Denmark and Sweden. [published online January 5, 2019]. Ann Rheum Dis. doi:10.1136/annrheumdis-2018-214326