Association of country-specific socioeconomic factors with survival of patients who experience severe classic acute graft-vs.-host disease after allogeneic hematopoietic cell transplantation. An analysis from the transplant complications working party of the EBMT Andrzej Frankiewicz, Christophe Peczynski, Sebastian Giebel, Alenca Harrington, Gerard Socié, Dietger Niederwieser, Christoph Scheid, Martin Bornhäuser, Nicolaus Kröger, Ahmet Elmaagacli, Boris Afanasyev, Peter Dreger, Claudia Rössig, Didier Blaise, Christian Peter Kratz, Ibrahim Yakoub-Agha, Bernhard Kremens, Charlotte Marie Niemeyer, Gerald Wulf, Igor W. Blau, Olaf Penack, Hildegard T. Greinix and Grzegorz W. Basak