Funding for this research was provided by:
National Natural Science Foundation of China (81671078)
Shanghai Municipal Population and Family Planning Commission (201840319)
Received: 10 June 2019
Accepted: 25 March 2020
First Online: 6 April 2020
Ethics approval and consent to participate
: This retrospective database analysis study was approved by the institutional review board of Shanghai Chest Hospital Ethics Committee, and the requirement to obtain informed consent was waived.
: Not applicable.
: The authors declare that they have no competing interests.