Study tests the power of prayer and finds it could make matters worse

"We are praying for you ... you will be in my prayers." In this ostentatiously religious country, such phrases drop routinely from the lips of presidents, politicians and ordinary people when wishing someone well before an operation. But do prayers make any difference? If a major scientific study here is to be believed, the answer is, no. Indeed, if a patient knows there is organised prayer on his or her behalf, such intercession might actually make matters worse.

These are the main, if highly tentative, findings of one of the most ambitious exercises yet to evaluate the power of therapeutic prayer. The $2.5m (£1.4m) study was done over a decade at six major US medical centres and involved 1,800 patients who had heart bypass surgery.

The patients - 65 per cent of whom said they believed in the power of prayer - were split into three groups. Two were prayed for, the third was not. Of those who were prayed for, one group was told so, and the others were told merely that they may or may not be prayed for. Three congregations were recruited to do the praying, one Protestant and two from Catholic monasteries, and given the names of patients.

Prayers began the night before surgery, and continued for two weeks after, using the same intercession, for "a successful surgery and a quick healthy recovery with no complications". After 30 days, researchers went through the results, or lack of them. There was no significant difference between the groups, they found.

This study is no more likely than its many predecessors to resolve the issue. Indeed, sceptics and believers in the power of prayer claim prayer is a supernatural force, beyond the reach of science. Thus, even the most scrupulous research is ultimately pointless.

"God must be smiling broadly," said Sister Carol Rennie, the prioress of St Paul's Monastery in St Paul, Minnesota, one of three praying congregations. "It [the study] tells me frankly that God's way of working with people is a mystery, and that technology can't determine the effects of prayer."

But it has raised intriguing questions about whether people should be told others are praying for them. A slightly higher proportion of whose who knew they were the subject of prayers suffered complications than those who did not.

The difference was very small - 59 per cent compared to 51 per cent - but researchers wonder if the problems among those who knew they were being prayed for reflected in part a "performance anxiety," said Charles Bethea, an Oklahoma cardiologist and an author of the study. "It may have made them uncertain, wondering, 'Am I so sick they had to call in a prayer team?'"

That is conjecture. But two things are certain. A study supposed to be the last word on the subject will be followed by others. And, whether or not it works, Americans will keep on praying.