Idea of comparative effectiveness research

The idea of comparative effectiveness research is to provide information about the value of different tools. Once that information is available, however, who should make the decisions about whether to provide coverage and reimbursement for a particular good or service? Can one objectively assess the potential harms and benefits associated with mammograms or other services or medications? Should decisions be made solely by the patient and treating provider? Does it matter if decisions affect taxpayers (for example, if a patient is covered by a government program such as Medicare or the Veterans Administration)?