CSF3 and acute graft versus host disease: Conversely, late initiation of G‐CSF (Days 5–10) was significantly associated with a higher risk of grades II–IV acute GVHD following BMT (HR 1.27, 95% CI 1.09–1.48, p = .002) and PBSCT (HR 1.28, 95% CI 1.07–1.53, p = .006) compared to those not receiving it.