1 Health Economics Research Centre, Nuffield Department of Population Health, University of Oxford, United Kingdom.
2 Berlin University of Technology, Faculty of Economics and Management, Department of Health Care Management, Straße des 17. Juni 135, 10623 Berlin, Germany; European Observatory on Health Systems and Policies, Berlin Area, Germany.
3 NIVEL (Netherlands institute for health services research), P.O. Box 1568, 3500 BN Utrecht, The Netherlands. Electronic address: m.rijken@nivel.nl.