Received: 10 September 2021
Accepted: 25 January 2022
First Online: 4 February 2022
: The original datasets were collected by the Korea Institute for Health and Social Affairs and the Seoul National University Institute for Social Welfare in Korea. The Institutional Review Board (IRB) of Seoul National University approved the study protocol, including consent form, data collection, and data analysis, and extended the IRB approval every year. Since we only used publicly available datasets as secondary data, no additional consent form from the participants was required in our study. The participants’ identifiable information was completely anonymized before analyzing the datasets, and all methods were performed in accordance with the relevant guidelines and regulations in our study. No additional administrative permission was required to access or use the datasets.
: Not applicable
: The authors declare no conflict of interest.