1 Department of Medicine, Hospital Selayang, Kepong, Malaysia.
2 Department of Medicine, School of Medical Sciences, Universiti Sains Malaysia, Kota Bharu, Malaysia.
3 Department of Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia.
4 Disease Control Division, Ministry of Health, Putrajaya, Malaysia.
5 Gastroenterology and Hepatology Unit, Department of Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia. Electronic address: wahkheong2003@hotmail.com.