To cite the function of the kidney.epi package in publications use:

Bikbov B (2018). “R open source programming code for calculation of the Kidney Donor Profile Index and Kidney Donor Risk Index.” Kidney Diseases, 4, 269–-272. https://doi.org/10.1159/000492427.

Corresponding BibTeX entry:

  @Article{,
    author = {Boris Bikbov},
    title = {R open source programming code for calculation of the
      Kidney Donor Profile Index and Kidney Donor Risk Index},
    journal = {Kidney Diseases},
    year = {2018},
    volume = {4},
    pages = {269–-272},
    url = {https://doi.org/10.1159/000492427},
  }