1 Nivel (Netherlands Institute for Health Services Research), PO Box 1568, 3500 BN, Utrecht, The Netherlands. A.Scheffelaar@nivel.nl.
2 Department of Primary and Community Care, Radboud university medical center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands. A.Scheffelaar@nivel.nl.
3 Nivel (Netherlands Institute for Health Services Research), PO Box 1568, 3500 BN, Utrecht, The Netherlands.
4 Reinier van Arkel, Den Bosch, The Netherlands.
5 Department of Primary and Community Care, Radboud university medical center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands.
6 Faculty of Health and Social Sciences, University of South-Eastern Norway, Drammen, Norway.
7 Tilburg School of Social and Behavioral Sciences, Tranzo, Scientific Center for Care and Welfare, Tilburg University, Tilburg, The Netherlands.