Regimen response by severity, and relationship between severity and clinical subtype. (A) Best response by regimen category stratified by disease severity at the start of the regimen. Each dot represents a given patient within a regimen category and severity status colored by best response (responder status indicated by blue, and non-responder status indicated by gold). Within each regimen category, there was a higher number of regimens initiated in mild/moderate compared with severe disease. A comparable proportion of patients achieved a response to siltuximab w/wo corticosteroids during both mild/moderate (57%) and severe (42%) disease. Corticosteroids alone was associated with response in 1 patient during mild/moderate disease only. (B) Severe disease was strongly associated with TAFRO status (ꞵ = 3.14; 95% CI, 2.00-4.27; P < .001). The majority (91.2%) of regimens initiated in severe disease occurred in patients with TAFRO subtype, but regimens initiated in mild/moderate disease occurred equally among patients with TAFRO (50.3%) and NOS (49.7%) subtypes.