Late initiation of G‐CSF was significantly associated with a higher risk of overall chronic GVHD following BMT (HR 1.22, 95% CI 1.02–1.47, p = .025) and CBT (HR 1.44, 95% CI 1.11–1.87, p = .006) compared to those not receiving it (Table S2). The gene discussed is CSF3; the disease is chronic graft versus host disease.