1. Department of Child Health, College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Oman
2. Department of Family Medicine and Public Health, College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Oman
3. Department of Epidemiology, School of Public Health, Boston University, MA, USA
4. Department of Behavioral Medicine, College of Medicine and Health Sciences, Sultan Qaboos University, P.O. Box 35, Al-Khoudh, 123 Muscat, Oman
5. College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Oman