1. Division of Family Medicine, Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
2. Department of Family Medicine, National University Health System, 1E Kent Ridge Rd, Singapore 119228, Singapore
3. National University Polyclinics, National University Health System, Singapore 609606, Singapore
4. Saw Swee Hock School of Public Health, National University of Singapore, Singapore 117549, Singapore