Ethical approval was obtained from the National Health- care Group Domain Specific Review Board in Singapore. The patients were informed that their participation in this study was completely voluntary a the ample time to at any time. The participants were given ample time to consider participating in the study without any pressure from the researcher. Their personal information such as name and identification number was not recorded to maintain their privacy and anonymity. Data were securely locked and kept confidential , while access to the data was only granted to the investigators of this study