Author contributions
DG: study concept and design; data entry; analysis and interpretation of data; drafting of the manuscript; critical revision of the manuscript for important intellectual content; statistical analysis. SG: study concept and design; data entry; analysis and interpretation of data; drafting of the manuscript; critical revision of the manuscript for important intellectual content; statistical analysis. MWR: study concept and design; acquisition of data; analysis and interpretation of data; critical revision of the manuscript for important intellectual content. All authors read and approved the final manuscript.