Contribution to authorship
J.H.Y. Q. Z. and T.X.N. supervised the entire study, including the conception, design, procedures and completion. L.L.Y., T.X.N., Y.Y.Y. and M.D.X. took the responsibility for the collection of data. L.L.Y. and T.X.N. were responsible for the data analysis and first draft of article. J.H.Y. T.X.N. and M.D.X. participated in the interpretation of the study data and in revisions to the article. All authors reviewed and approved the final version of this work.