1. Institute of Public Health, Medical Faculty; Heidelberg University; Heidelberg Germany
2. Ahmadu Bello University; Zaria Nigeria
3. Institute of Medical Biometry and Informatics; University Hospital Heidelberg; Heidelberg Germany
4. Department of Community Medicine; Ahmadu Bello University; Zaria Nigeria
5. Center for Health Policy Studies; Zhejiang University School of Medicine; HangZhou China