Text and Data Mining valid from 2020-01-09
Received: 10 September 2019
Accepted: 23 December 2019
First Online: 9 January 2020
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: Ethical approval was obtained from the Ethics Committee of Qingdao Mental Health Center (No. QMHC2015021156673). All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
: Informed consent was obtained from all individual participants included in the study.