1. University Hospital of Cologne; Cochrane Haematological Malignancies Group, Department I of Internal Medicine; Kerpener Str. 62 Cologne Germany 50924
2. University Hospital of Cologne; Department I of Internal Medicine, Center of Integrated Oncology Köln Bonn; Kerpener Str. 62 Cologne Germany 50924
3. MRC Biostatistics Unit; Cambridge UK