Funding for this research was provided by:
the Tianjin Health and Family Planning Commission (13KG119)
Received: 20 May 2019
Accepted: 9 October 2019
First Online: 29 November 2019
Ethics approval and consent to participate
: The study protocol was approved by the medical ethics committee of the Tianjin Mental Health Center and all respondents signed informed consent before participation.
: Not applicable.
: The authors declare that they have no competing interests.