1. Department of Emergency Medicine, Aga Khan University , Karachi 74800 , Pakistan
2. Department of Community Health Sciences, Aga Khan University , Karachi 74800 , Pakistan
3. University of Michigan, School of Public Health , Ann Arbor, Michigan 48109 , USA
4. School of Nursing and Midwifery, Aga Khan University , Karachi 74800 , Pakistan