How effective are JAK-inhibitors? Perspectives from clinical trials and real-world studies.

Introduction JAK-inhibitors have emerged as a new treatment option for rheumatoid arthritis, with five molecules currently available in different parts of the world: tofacitinib, baricitinib, upadacitinib, peficitinib and filgotinib. These molecules have been the subject of numerous trials looking at their efficacy (how well they perform in controlled conditions) but also some observational studies from the general population to assess their effectiveness (how well treatment perform under real conditions). With each their own weaknesses and strengths, they give different but complementary information. Areas covered We will review what we can learn from trials and real-world studies on how effective JAK-inhibitors are in the treatment of rheumatoid arthritis. Expert opinion Trials of JAK-inhibitors have shown that JAK-inhibitors are efficacious for the treatment of rheumatoid arthritis. However, their main outcomes are not clinically meaningful as their aim is mainly the regulatory authorisation of the product. Real-world studies are important as they evaluate the real-life effectiveness of the compounds, however, they are scarce at the moment, mainly evaluating tofacitinib and of variable quality. Future high-quality studies are needed to assess the real-world effectiveness of JAK-inhibitors in a more complete manner.