The study was conducted at 32 Department of
Veterans Affairs (VA) medical centers. It was approved
by the human rights committee at the
West Haven VA Cooperative Studies Program Coordinating
Center and by the institutional review
board at each participating site and was overseen
by an independent data and safety monitoring committee
chartered by the sponsor (the Cooperative
Studies Program of the VA Office of Research
and Development). All enrolled patients provided
written informed consent. The study protocol is
available with the full text of this article at
NEJM.org.