Recurrent fever and association with severe organ involvement, mortality and treatment outcomes in VEXAS syndrome: data from the AIDA Network.

Introduction: Recurrent febrile episodes account for one of the most frequent symptoms observed in Vacuoles, E1 enzyme, X-linked, Autoinflammatory, Somatic (VEXAS) syndrome and a key target for therapeutic intervention. Therefore, this study aims at investigating the association between recurrent febrile episodes and specific clinical manifestations, mortality and response to treatment. Methods: Data were obtained from the international AutoInflammatory Disease Alliance (AIDA) Network registry and analyzed using a Bayesian statistical approach. Posterior probabilities [P(β)] were calculated to assess the likelihood that fever was associated with clinical, laboratory, genetic, and therapeutic features. Results: In total, 87 VEXAS patients were enrolled, 65 (74.7%) of whom suffered from recurrent fever episodes. Fever episodes showed a significant association with patients' mortality [P(β): 99.41%], as well as with major inflammatory organ involvement, including cardiac [P(β): 99.99%], lung [P(β): 99.98%], and gastrointestinal [P(β): 97.5%] involvement. The occurrence of recurrent fever episodes was associated with a negligible probability of both complete response and treatment failure [P(β) <2.5%], instead favoring a partial response [P(β) >97.5%] to conventional disease modifying anti-rheumatic drugs, Janus Kinases inhibitors, and tocilizumab. For temperatures exceeding 40 °C, using anti-interleukin-1 agents was associated with a high probability of treatment failure [P(β): 99.3%]. Conclusions: febrile episodes are associated with more severe pattern of organ involvement and, accordingly, to death. Furthermore, febrile episodes could correlate with differential therapeutic responsiveness, thereby potentially serving as a valuable marker to guide the treatment strategies in VEXAS patients.