First Online: 8 August 2019
Ethics approval and consent to participate
: This project was approved by the Mayo Clinic and Olmsted Medical Center Institutional Review Boards. Because the study involved use of data collected from existing medical records, and included information from deceased patients, the requirement for informed consent was waived. However, the State of Minnesota requires that patients provide a general “research authorization” for their medical records to be used for research, and we only included the records of patients who had provided research authorization.
: Not applicable.
: The authors declare that they have no competing interests.
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