1. Clinical Epidemiology and Biostatistics; Faculty of Medicine and Health; Örebro University; Örebro Sweden
2. Faculty of Medicine and Health; School of Health and Medical Sciences; Örebro University; Örebro Sweden
3. Clinical Epidemiology Unit; Karolinska University Hospital; Karolinska Institutet; Stockholm Sweden
4. Department of Epidemiology and Public Health; University College London; London UK