Received: 16 August 2019
Accepted: 25 September 2019
First Online: 24 October 2019
Ethics approval and consent to participate
: We only collected the total number of CVD outpatient visits, and the selection was not related to outpatients’ personal privacy (i.e., not including personal name, gender, ethnicity, body weight, etc.), and the data belong to de-identification. The study protocol was approval by Medical Ethics Committee in Hebei Medical University (No.20180062).
: Not applicable.
: The authors declare that they have no competing interests.