1. INSERM, UMRS 1138, team 22, CRC, University Paris 5; University Paris 6; Paris France
2. Federal Institute for Drugs and Medical Devices; Bonn Germany
3. INSERM, UMR 1123, Hôpital Robert-Debré, APHP; University Paris 7; Paris France
4. Department of Medical Statistics; University Medical Center Göttingen; Göttingen Germany
5. Statistics and Epidemiology, Division of Health Sciences, Warwick Medical School; The University of Warwick; Warwick UK
6. INSERM, CIC 1414; University Rennes-1; Rennes France
7. INSERM, IAME UMR 1137; University Paris Diderot; Paris France