1. Department of General Practice, Erasmus University Medical School, Rotterdam, The Netherlands
2. Department of Epidemiology and Biostatistics, Erasmus University Medical School, Rotterdam, The Netherlands
3. Department of Surgery 3, Ruwaard van Putten Hospital, Spijkenisse, The Netherlands
4. Julius Centre for Patient-Oriented Research, Utrecht University, Utrecht, The Netherlands
5. Department of General Practice, Utrecht University, Utrecht, The Netherlands