passages: PMC-3212806-sec-17__text
passages: sec
passages: Authors' contributions
  EEKN was responsible for data collection, statistical analysis and drafting the manuscript. SAGN and YW involved in data collection and helped with the data analysis. AS helped in data analysis. EST and JL directed the study and helped in revising the manuscript. RMVD helped in data analysis, interpretation of the results and led writing of the manuscript. All authors read and approved the final manuscript.
  