Serious infection risk compared across different biologicals
medwireNews: Findings from two registry studies of patients with rheumatoid arthritis (RA) suggest that serious infection risk may differ by the type of biological agent used.
The first study, an analysis of a US claims database by Seoyoung Kim and colleagues from Brigham and Women’s Hospital in Boston, Massachusetts, USA, included 22,496 patients who initiated abatacept or a tumour necrosis factor (TNF) inhibitor between 2006 and 2015.
They demonstrated that among the 11,248 abatacept-treated patients, 188 hospital admissions due to infection occurred over an average 168 days of follow-up on active treatment, compared with 219 among the 11,248 propensity-matched patients given TNF inhibitors over an average 150 days of follow-up, giving incidence rates of 37 versus 47 per 1000 person–years.
These findings translate into a significant 22% reduced risk for infection among patients treated with abatacept versus TNF inhibitors, which “was driven mostly by infliximab”, say the study authors.
When the TNF inhibitors were considered separately, abatacept was associated with a significant 37% lower serious infection risk than infliximab, but there was no significant risk reduction associated with abatacept relative to adalimumab or etanercept.
The researchers conclude in Arthritis Care & Research that “RA patients with specific concerns about infections may benefit from use of abatacept compared to TNF [inhibitors]”.
The second study, published in the Annals of the Rheumatic Diseases, compared the serious infection risk associated with three non-TNF inhibitor biologicals, namely abatacept, rituximab and tocilizumab, in RA patients from Denmark and Sweden.
The investigation included 6648 individuals from the DANBIO and ARTIS registries who received 8987 treatment courses – 2725 with abatacept, 3363 with rituximab and 2899 with tocilizumab – from 2010 to 2015. A total of 456 cases of infection requiring hospital admission were reported during the first year of treatment, and 639 cases occurred over 2 years.
Although not statistically significant, Kathrine Lederballe Grøn, from the University of Copenhagen in Denmark, and co-researchers found numerical differences in infection rates between the different treatment groups.
After adjustment for age and sex, 1-year incidence rates of serious infection in the Danish cohort were highest in patients treated with rituximab, at 8.1 per 100 person–years, followed by abatacept and tocilizumab, at 7.1 and 6.1 per 100 person–years, respectively. The corresponding 2-year rates were 7.5, 6.1 and 5.2 per 100 person–years, and a similar pattern of results was observed in the Swedish database.
While serious infection risk “seemed to vary with drug”, the investigators note that “[t]he findings should be interpreted with caution due to the few events and the risk of residual confounding”.
They conclude that the results “do not support that one non-TNF [inhibitor] should be recommended over the other for patients with RA at high risk of [serious infections].”
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