Contribution to authorship
Author Contributions: Miss Chu had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Dr Liu contributed equally to the work as co–senior authors.
Concept and design: Chu, Liu and Zhang.
Acquisition, analysis, or interpretation of data: Chu, Liu, Qi, Ma, Zhang.
Drafting of the manuscript: Chu and Liu.
Critical revision of the manuscript for important intellectual content: Wen, Li,
Cheng, Liang, Kafle, Wu, Wang and Chu
Statistical analysis: Ye and Chu.
Administrative, technical, or material support: Ye, Wen and Zhang
Supervision: Zhang