1. Institute of Medical Statistics and Computational Biology; Faculty of Medicine and University Hospital Cologne, University of Cologne; Cologne Germany
2. Institute of Health Economics and Clinical Epidemiology; University of Cologne, Faculty of Medicine and University Hospital Cologne; Cologne Germany
3. Cochrane Haematology, Department I of Internal Medicine, Center for Integrated Oncology Aachen Bonn Cologne Duesseldorf; Faculty of Medicine and University Hospital Cologne, University of Cologne; Cologne Germany
4. Institute of Social and Preventive Medicine; University of Bern; Bern Switzerland
5. Cochrane Cancer, Department I of Internal Medicine, Center for Integrated Oncology Aachen Bonn Cologne Duesseldorf; Faculty of Medicine and University Hospital Cologne, University of Cologne; Cologne Germany