. Written informed consent was obtained from each volunteer participating in this study. All procedures of the protocol have been approved by Health Research Ethics Committee, Faculty of Medicine, Universitas Indonesia (Approval letter no. 329/PT02.FK/ETIK/2012 on May 28, 2012). The sample size was calculated based on the formula of two independent proportion, and 42 subjects in each group was needed. With additional anticipated 10% drop out, 94 subjects were finally recruited.