Ellen Van de Poel1,2
, Ahmad Reza Hosseinpoor3
, Caroline Jehu-Appiah4
, Jeanette Vega3
and Niko Speybroeck5 
1
Department of Applied Economics, Erasmus University Rotterdam, Burg. Oudlaan 50, 3000 DR Rotterdam, The Netherlands
2
The Faculty of Economics and Commerce, The University of Melbourne, Victoria 3010, Australia
3
Equity, Poverty and Social Determinants of Health, Evidence and Information for Policy, World Health Organization, Avenue Appia 20, CH - 1211 Geneva 27, Switzerland
4
Policy Planning Monitoring and Evaluation Division, Ghana Health Service, Private Mail Bag, Ministries, Accra, Ghana
5
Institute of Tropical Medicine, Nationalestraat 155, 2000 Antwerp, Belgium