medwireNews: Real-world study findings from Claudia Salinas (Eli Lilly and Company Corporate Center, Indianapolis, Indiana, USA) and team suggest that people with rheumatoid arthritis (RA) treated with the Janus kinase (JAK) inhibitor baricitinib may have a significantly higher risk for venous thromboembolism (VTE) than those on tumor necrosis factor (TNF) inhibitors.
These results follow those from the ORAL Surveillance trial, which demonstrated higher rates of major adverse cardiovascular events (MACE) and VTE among high-risk RA patients treated with tofacitinib versus TNF inhibitors, which led the US FDA to mandate updated safety warnings on the labels for all JAK inhibitors.
However, it is not yet known whether the risks demonstrated in the ORAL Surveillance trial represent a class effect, and Salinas and team say that “[f]ew studies have assessed the comparative risk of VTE associated with JAK [inhibitors].”
To address this, the researchers used 14 real-world data sources from the USA, Europe, and Japan to evaluate the risk for adverse outcomes among 7606 RA patients treated with baricitinib and the same number of propensity score-matched individuals treated with TNF inhibitors. The average duration of follow-up in the baricitinib and TNF inhibitor groups was 9 months and 10 months, respectively.
A total of 97 patients experienced a VTE during the study period, of whom 58% were treated with baricitinib and 42% with TNF inhibitors. These findings translated into a significantly elevated risk for VTE in the baricitinib group, with an incidence rate ratio (IRR) of 1.51.
Based on estimated incidence rate differences, the study authors say that “assuming a constant rate over time, for every 1000 patients treated with baricitinib instead of a TNF [inhibitor], an additional three VTE would be expected each year.”
They also found that patients treated with baricitinib had a numerically greater risk for MACE (IRR=1.54) and serious infection (IRR=1.36) compared with those on TNF inhibitors, albeit without reaching statistical significance. In all, 58% of the 93 patients who experienced MACE were in the baricitinib group, as were 55% of the 321 with serious infections.
Salinas and colleagues caution in Rheumatology and Therapy that their study had a number of limitations, including the short duration of follow-up and “limited ability to control for confounding by lifestyle factors.”
They note that in the future, findings from the ongoing RA-BRANCH (NCT04086745) and RA-BRIDGE (NCT03915964) trials “will be available to provide a more complete understanding of the risk of VTE, MACE, and serious infection” in patients treated with baricitinib versus TNF inhibitors in high-risk patients with an inadequate response or intolerance to conventional or biologic DMARDs.
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