Funding for this research was provided by:
Received: 18 February 2019
Accepted: 2 August 2019
First Online: 9 August 2019
Ethics approval and consent to participate
: The data extracts were de-identified prior to their release to study investigators, and thus their use for health services research is compliant with the HIPAA Privacy Rule and federal guidance on Public Welfare and the Protection of Human Subjects and is exempt from IRB review.
: Not applicable.
: DW, RD, AH, and AL are employed by Policy Analysis Inc. (PAI). CB, RB, DC, and MB are employed by, and own stock in, Amgen Inc. GHL is the principal investigator on a research grant to Fred Hutchinson Cancer Research Center from Amgen Inc.