1. Department of Clinical Sciences and Community Health University of Milan Milan Italy
2. Department of Methodology and Statistics Tilburg University Tilburg The Netherlands
3. Department of Humanities Università Telematica Pegaso Naples Italy
4. Department of Medical and Surgical Sciences University of Bologna Bologna Italy
5. Department of Epidemiology and Health Services Research Centre for Primary Care and Public Health (Unisanté) University of Lausanne Lausanne Switzerland