Funding for this research was provided by:
National Institutes of Health (U01DA021525, U01DA038886)
Canadian Institutes of Health Research (MSH-141971)
Received: 14 November 2017
Accepted: 12 January 2018
First Online: 19 January 2018
Ethics approval and consent to participate
: Participants from VIDUS and ACCESS cohorts have provided informed consent. The cohorts have received ethical approval by the University of British Columbia/Providence Health Care Research Ethics Board.
: Not applicable
: The authors declare that they have no competing interests.
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