- Steroid refractory GVHD is defined as GVHD that has progressed (increasing in grading) despite 49 hours of treatment with methylprednisolone of ≥ 2.0 mg/kg OR GVHD that has failed to improve (no change in grading stage) despite 4 days of treatment with methylprednisolone of ≥ 2.0 mg/kg