1. CAPHRI School for Public Health and Primary Care, Maastricht University Medical Centre; Department of Family Medicine; Maastricht Netherlands
2. Public Health Service of Haaglanden; Epidemiology; The Hague Netherlands
3. Maastricht University (CAPHRI); Department of Family Medicine; Maastricht Netherlands
4. Heinrich-Heine-University; Institute of General Practice, Addiction Research and Clinical Epidemiology, Medical Faculty; Düsseldorf Germany