1. Department of General Practice , Erasmus MC, , 3000 CA Rotterdam , the Netherlands
2. University Medical Centre Rotterdam , Erasmus MC, , 3000 CA Rotterdam , the Netherlands
3. Department of Clinical Psychology, Open University , 6419 AT Heerlen , the Netherlands
4. Department of Public Health , Erasmus MC, , 3000 CA Rotterdam , the Netherlands
5. Department of Youth , City of Rotterdam, Rotterdam, The Netherlands