Author contributions
The authors meet criteria for authorship as recommended by the International Committee of Medical Journal Editors. Y.S.J. and C.K.R. take responsibility for the data and results. All investigators of the KOCOSS cohort contributed to the acquisition of data. C.K.R. designed the study and S.H. and D.L. conducted statistical analysis. Y.S.J. reviewed analysed data and wrote the initial manuscript. All authors provided critical review and approved of the version to be published.