1. Department of General Practice/Centre for Quality of Care Research (WOK), Care and Public Health Research Institute (CAPHRI), Maastricht University, Maastricht, The Netherlands,
2. Department of General Practice/Centre for Quality of Care Research (WOK), Care and Public Health Research Institute (CAPHRI), Maastricht University, Maastricht, The Netherlands
3. Department of Social Medicine, VU University Medical Centre, Amsterdam, The Netherlands