1. Spanish Centre for Pharmacoepidemiologic Research (CEIFE), Madrid, Spain;
2. Servicio de Aparato Digestivo, Hospital Clínico, University of Zaragoza, IIS Aragón, Zaragoza, Spain;
3. CIBERehd, Madrid, Spain;
4. Epidemiology, Bayer AG, Berlin, Germany;
5. Department of Public Health and Maternal Child Health, Faculty of Medicine, Complutense University of Madrid, Madrid, Spain