1 Department of Clinical Epidemiology and Department of Biomedical Data Sciences, Leiden University Medical Center, Leiden 2333 ZA, Netherlands. Electronic address: M.van_Smeden@lumc.nl.
2 Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, TN, USA.
3 Department of Epidemiology and Public Health, University College Cork, Cork, Ireland.