NRM and OS after grade 3 to 4 aGVHD, stratified by adequate CD4⁺IR before aGVHD diagnosis. Cumulative incidence plot showing NRM after grade 3 to 4 aGVHD in the UMC/PMC cohort (A) and Kaplan-Meier curve showing OS (B). CD4⁺ IR was defined as ≥50 CD4⁺ T cells per μL in 2 consecutive measurements before aGvHD diagnosis (blue lines) and with no CD4⁺ IR (red lines).