I often tell my patients and their family that I would pray for them. But I know that there are many things to consider when physicians are asked to pray or they offer prayers. Here are nice references.
AMA Journal of Ethics : How Should Clinicians Respond to Requests from Patients to Participate in Prayer?
April R. Christensen, MD, Tara E. Cook, MD, and Robert M. Arnold, MD
#120 Fast Fact : Physicians and Prayer Requests Kate Kwiatkowski , Robert Arnold MD , David Barnard PhD