Received: 17 June 2020
Accepted: 17 February 2021
First Online: 18 March 2021
Ethics approval and consent to participate
: Since the claims data we used was an anonymized database and had no impact on patients’ health, informed consent was exempted. This study was approved by the Ethics Committee of Beijing University of Chinese Medicine (No.2019BZHYLL0201).
: Not applicable.
: The authors declare that they have no competing interests.