In the studied cohorts, 28 of 29 MAS episodes (97%) occurring while patients were receiving IL‐1 pathway–targeted treatment (either anakinra or canakinumab) met the EULAR/ACR/PRINTO 2016 classification criteria for MAS in sJIA‐SD26 before the initiation of MAS‐directed therapy (Table 2). Here, IL1B is linked to macrophage activation syndrome.