Having people pray for heart bypass patients had no effect on their recoveries in an American study, researchers say.

The scientists, led by Dr. Herbert Benson of Harvard Medical School, emphasized that they looked only at the effect of prayer on the patients in their study – and could not address questions such as whether God exists or answers prayers.

The research, which is to be published in the April 2006 issue of the American Heart Journal, involved about 1,800 patients at six medical centres.

Three Christian groups were asked to pray for particular patients, starting the night before their surgeries and continuing for two weeks.

The volunteers were given a patient's given name and last initial, and prayed for "a successful surgery with a quick, healthy recovery and no complications."

Patients were divided into three groups:

  • One set of patients was being prayed for and knew it.
  • The second group was also the subject of prayers, but only knew it was a possibility.
  • Patients in the third group weren't prayed for, although they were told they might be.

The researchers did not tell patients or their families or friends to change their plans for praying, saying it would have been impractical and unethical to do so.

More complications among patients who knew they were prayed for

The patients were then monitored for 30 days for any complications.

The results showed no effect of prayer on the patients' recovery, the researchers said in the journal article, Study of the Therapeutic Effects of Intercessory Prayer (STEP) in cardiac bypass patients.

The study found 59 per cent of the patients who knew they were being prayed for developed medical complications. Among those who thought they might be prayed for, 52 per cent had complications.

The researchers said they had no explanation for the higher complication rate among patients who knew they were being prayed for.

The work was funded by the Templeton Foundation, which supports research into science and religion.