1. University Hospital of Cologne; Cochrane Haematological Malignancies Group, Department I of Internal Medicine; Kerpener Str. 62 Cologne Germany 50937
2. University Hospital of Cologne; Institute of Medical Statistics and Computational Biology; Kerpener Str. 62 Cologne Germany 50937
3. University Hospital of Cologne; Institute of Medical Statistics, Informatics and Epidemiology; Kerpener Str. 62 Cologne Germany 50937
4. University of Heidelberg; Department of Medicine V; Heidelberg Germany