Received: 10 November 2021
Accepted: 17 December 2021
First Online: 23 November 2022
: The study was approved by the Ethics Committee of School of Public Health, Shandong University and conducted in accordance with the ethical guidelines of the Declaration of Helsinki of the World Medical Association. The data used are all deidentified, consent to participate is not applicable.
: Not applicable.
: Authors have no competing interests relevant to this paper.