The Standards for the Reporting of Observational Studies in Epidemiology (STROBE) were fol-lowed in this study. The study protocol was approved by the Ethics Committee of the Faculty of Tropical Medicine, Mahidol University, and the Ethics Committee of the CCIT in Thailand. Written informed consent was not obtained as it was specifically waived by the approving Eth-ics Committee of the Faculty of Tropical Medicine and the CCIT. Data were anonymized before analysis by de-identifying patient data.