1. Department of Pediatrics, Faculty of Medicine, Prince of Songkla University, Songkhla 90110, Thailand
2. Office of National Health Examination Survey, Health System Research Institute, Bangkok 11000, Thailand
3. Department of Community Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand
4. Faculty of Public Health, Mahidol University, Bangkok 10400, Thailand