Patients being prayed for were as likely as others to develop complications such as heart attacks, be readmitted to hospital or die, the study said. Bedside therapy involving music, imagery and touch didn't have a significant effect either, researchers found.
I know that for a lot of people it is just about the affect on the recipient of the prayers/thoughts/meditation but there is also the secondary impact on the actor. The one, or in many situations, the congregation, are able to receive some sort of benefit for the act of prayer. Whether or not that benefit comes from a higher being seems to be immaterial in my eyes. What is important is that it relieves some of the anxiety, some of the fears, and some of the trepidation you have about your friend who is in the hands of a third party surgeon.