Most research in the field looks at how people who are sick are affected by their own spiritual beliefs and practices. In general, these studies have suggested that people who are religious seem to heal faster or cope with illness more effectively than do the nondevout.
But a few scientists have taken a further step: They're trying to find out if you can help strangers by praying for them without their knowledge.
A recent, controversial study of cardiac patients conducted at St. Luke's Hospital in Kansas City, Missouri, concludes that this type of prayer -- known as intercessory prayer -- may indeed make a difference. "Prayer may be an effective adjunct to standard medical care," says cardiac researcher William Harris, Ph.D., who headed the St. Luke's study. The study was published in the October 25, 1999 issue of the Archives of Internal Medicine.
Harris and team examined the health outcomes of nearly 1,000 newly admitted heart patients at St. Luke's. The patients, who all had serious cardiac conditions, were randomly assigned to two groups. Half received daily prayer for four weeks from five volunteers who believed in God and in the healing power of prayer. The other half received no prayer in conjunction with the study.
The volunteers were all Christians. The participants were not told they were in a study. The people praying were given only the first names of their patients and never visited the hospital. They were instructed to pray for the patients daily "for a speedy recovery with no complications."
Using a lengthy list of events that could happen to cardiac patients -- such as chest pains, pneumonia, infection, and death -- Harris concluded that the group receiving prayers fared 11% better than the group that didn't, a number considered statistically significant.
Harris originally embarked on his study to see if he could replicate a similar 1988 study of intercessory prayer conducted at San Francisco General Hospital. That study -- one of the only published studies of its kind -- also found that prayer benefited patients, but by a different measure: The patients were able to go home from the hospital sooner.
In Harris' study, the length of the hospital stay and the time spent in the cardiac unit were no different for the two groups.
Still, Harris says, his study bolsters the evidence that prayer works. "To me it almost argues for another intelligence, to have to redirect this very vague information."
At the very least, he says, his results validate the need for more research. "It strengthens the field. The more studies done in independent, different places, the closer you are to the truth," he says.
Fans and Critics
The Harris study, like its predecessor, has attracted both fans and critics, and plenty of each. Some critics say that adding up health events to judge a patient's outcome is subjective, open to bias, and therefore scientifically invalid. Others say not informing people they were in a study is unethical and disrespects personal religious preferences.
"This was a reasonably well conducted study, [but] I think they made some mistakes," says Richard Sloan, Ph.D., a cardiovascular researcher at Columbia Presbyterian Medical Center in New York who closely follows research on spirituality and healing.
Sloan has trouble with several aspects of the Harris study. The prayers were for a "speedy recovery" but there were no measurable differences in hospital stays for the two groups, he says. "Half of their predictions failed at the offset."
But supporters say the work is careful. "They're not claiming they are identifying how this occurred; they're just saying maybe we should take a closer look," says Harold Koenig, M.D., a doctor and professor of medicine and psychiatry at Duke University who has written about prayer and healing.
The percent of difference in the outcomes of the two groups was small, Koenig says, but the Harris study used sound methodology and produced intriguing results. "Many, many people pray. Many people would like to know if their prayers are being heard."