This study investigated why some children with juvenile spondyloarthritis (JSpA) do not respond to TNF inhibitors (TNFi), a common treatment. Researchers analyzed data from patients enrolled in the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry between July 2015 and January 2019. They focused on children with enthesitis-related arthritis, psoriatic arthritis, and undifferentiated spondyloarthritis who either didn’t respond to TNFi at all (primary non-responders) or initially responded but then lost effectiveness (secondary non-responders).

Out of 287 patients, 124 were non-responders, with most being secondary non-responders. On average, non-responders stopped TNFi after about 275 days. The study found that non-responders were more likely to be female and had a higher Body Mass Index (BMI). They also had more severe disease symptoms, including arthritis, enthesitis (inflammation where tendons or ligaments attach to bone), and sacroiliitis (inflammation of the joints at the base of the spine), both before starting and after starting TNFi treatment.

Most non-responders switched to another TNFi, a disease-modifying anti-rheumatic drug (DMARD), or a different biologic treatment after their initial TNFi failed. The study concluded that children with more severe disease and higher BMI are less likely to respond to TNFi, highlighting the need for alternative treatment strategies for these patients.