Received: 5 January 2018
Accepted: 14 January 2019
First Online: 1 February 2019
Ethics approval and consent to participate
: Not applicable. The population-based mortality surveillance is our routines. Original data of this study is part of a screening survey organized by the Guangdong Provincial Commission of Health and Family Planning. All data used for this study were permitted to use.
: Not applicable.
: The authors declare that they have no competing interests.
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