Studies on intercessory prayer
- For a general discussion of the philosophical and religious issues, please see Efficacy of prayer.
Some religions claim that praying for somebody who is sick can have positive effects on the health of the person being prayed for. Adherents of those religions believe that prayer, like forgiveness, has a positive effect on the health and well-being of the person doing the prayer or forgiveness.
Meta-studies of the literature in the field have been performed showing evidence only for no effect or a potentially small effect. For instance, a 2006 meta analysis on 14 studies concluded that there is "no discernible effect" while a 2007 systemic review of intercessory prayer reported inconclusive results, noting that 7 of 17 studies had "small, but significant, effect sizes" but the review noted that the most methodologically rigorous studies failed to produce significant findings.
In comparison to other fields that have been scientifically studied, carefully monitored studies of prayer are relatively few. The field remains tiny, with about $5 million spent worldwide on such research. If and when more studies of prayer are done, the issue of prayer's efficacy may be further clarified.
The third party studies discussed here have all been performed using Christian prayers. Some have reported null results, some have reported correlations between prayer and health, and some have reported contradictory results in which beneficiaries of prayer had worsened health outcomes. The parameters used within the study designs have varied, for instance, daily or weekly prayers, whether to provide patient photographs, with full or partial names, measuring levels of belief in prayer, and whether patients underwent surgery.
In 1872, the Victorian scientist Francis Galton made the first statistical analysis of third-party prayer. He hypothesized, partly as satire, that if prayer were effective, members of the British Royal Family would live longer than average, given that thousands prayed for their well-being every Sunday, and he prayed over randomized plots of land to see whether the plants would grow any faster, and found no correlation in either case.
Byrd and Harris
A 1988 study by Randolph C. Byrd used 393 patients at the San Francisco General Hospital coronary care unit (CCU). Measuring 29 health outcomes using three-level (good, intermediate, or bad) scoring, the prayer group suffered fewer newly diagnosed ailments on only six of them. Byrd concluded that "Based on these data there seemed to be an effect, and that effect was presumed to be beneficial", and that "intercessory prayer to the Judeo-Christian God has a beneficial therapeutic effect in patients admitted to a CCU." The reaction from the scientific community concerning this study was mixed. Several reviewers considered Byrd’s study to be well-designed and well-executed, while others remained skeptical. A criticism of Byrd's study, which also applies to most other studies, is the fact that he did not limit prayers by the friends and family of patients, hence it is unclear which prayers, if any, may have been measured.
A 1999 follow-up by William S Harris et al. attempted to replicate Byrd's findings under stricter experimental conditions, noting that the original research was not completely blinded and was limited to only "prayer-receptive" individuals (57 of the 450 patients invited to participate in the study refused to give consent "for personal reasons or religious convictions"). Using a different, continuous weighted scoring system – which admittedly was, like Byrd's scoring, "an unvalidated measure of CCU outcomes" – Harris et al. concluded that "supplementary, remote, blinded, intercessory prayer produced a measurable improvement in the medical outcomes of critically ill patients", and suggested that "prayer be an effective adjunct to standard medical care." However, when they applied Byrd’s scores to their data, they could not document an effect of prayer using his scoring method. Critics have suggested that both Byrd's and Harris's results can be explained by chance. Dr. Richard P. Sloan, PhD, compared the Byrd and Harris studies with the sharpshooter fallacy, "searching through the data until a significant effect is found, then drawing the bull's-eye."
A 1997 study by O'Laoire measured the effects on the agents performing daily prayers and reported benefits not only for the beneficiaries, but also for the agents, and the benefit levels correlated with the belief levels of agents and beneficiaries in some cases. The study measured anxiety and depression. This study used beneficiary names as well as photographs.
In 1998 Fred Sicher et al. performed a small scale double-blind randomized study of 40 patients with advanced AIDS. The patients were in category C-3 with CD4 cell counts below 200 and each had at least one case of AIDS-defining illness. The patients were randomly assigned to receive distant intercessory healing or none at all. The intercession took place by people in different parts of the United States who never had any contact with the patients. Both patients and physicians were blind to who received or did not receive intercession. Six months later the prayer group had significantly fewer AIDS illnesses, less frequent doctor visits, and fewer days in the hospital. However, CD4 counts and scores on other physiological tests had no significant variation between the two groups of patients.
A 2001 double-blind study at the Mayo Clinic randomized 799 discharged coronary surgery patients into a control group and an intercessory prayer group, which received prayers at least once a week from 5 intercessors per patient. Analyzing "primary end points" (death, cardiac arrest, rehospitalization, etc.) after 26 weeks, the researchers concluded "intercessory prayer had no significant effect on medical outcomes after hospitalization in a coronary care unit."
The IVF-ET prayer scandal
In 2001 the Journal of Reproductive Medicine published an experimental study by three Columbia University researchers indicating that prayer for women undergoing in vitro fertilization-embryo transfer (IVF-ET) resulted in a double success rate (50%) of pregnancy compared to that of women who did not receive prayer. Columbia University issued a news release saying that the study had been carefully designed to eliminate bias. The most important skeptic was Bruce Flamm, a clinical professor of gynecology and obstetrics at the University of California at Irvine, who not only found the experimental procedures flawed, but also discovered that some of the authors were frauds. The first-named author, Kwang Y. Cha, never responded to any inquiries. Daniel Wirth, a.k.a. John Wayne Truelove, is not an M.D. but an M.S. in parapsychology and was subsequently indicted on felony charges for mail fraud and theft, committed apparently during the time the study was said to have been conducted, and he pleaded guilty. On November 22, 2004, Wirth was sentenced to five years in prison followed by three years of supervised release (parole). In December 2001 an investigation of Columbia University by the U.S. Department of Health and Human Services (DHHS) revealed that the study’s lead author, Dr. Rogerio Lobo, first learned of the study six to twelve months after the study was completed, and he subsequently denied having anything to do with the study’s design or conduct and indicated that he had only provided editorial assistance. The name of Columbia University and Lobo were retracted.
Retroactive intercessory prayer
A 2001 study by Leonard Leibovici used records of 3,393 patients who had developed blood infections at the Rabin Medical Center between 1990 and 1996 to study retroactive intercessory prayer. To compound the alleged miraculous power of prayer itself, the prayers were performed after the patients had already left the hospital. All 3,393 patients were those in the hospital between 1990 and 1996, and the prayers were conducted in 2000. Two of the outcomes, length of stay in the hospital and duration of fever, were found to be significantly improved in the intervention group, implying that prayer can even change events in the past. However, the "mortality rate was lower in the intervention group, but the difference between the groups was not significant." Leibovici concluded that "Remote, retroactive intercessory prayer was associated with a shorter stay in hospital and a shorter duration of fever in patients with a bloodstream infection." Leibovici goes on to note that in the past, people knew the way to prevent diseases (he cites scurvy) without understanding why it worked. In saying so, he suggests that if prayer truly does have a positive effect on patients in hospital, then there may be a naturalist explanation for it that we do not yet understand. After many scientists and scholars criticized this retroactive study, Leibovici later stated that it was "intended lightheartedly to illustrate the importance of asking research questions that fit with scientific models."
The MANTRA study
A 2005 MANTRA (Monitoring and Actualisation of Noetic Trainings) II study conducted a three-year clinical trial led by Duke University comparing intercessory prayer and MIT (Music, Imagery, and Touch) therapies for 748 cardiology patients. The study is regarded as the first time rigorous scientific protocols were applied on a large scale to assess the feasibility of intercessory prayer and other healing practices. The study produced null results and the authors concluded, "Neither masked prayer nor MIT therapy significantly improved clinical outcome after elective catheterization or percutaneous coronary intervention." Neither study specified whether photographs were used or whether belief levels were measured in the agents or those performing the prayers.
The STEP project
Harvard professor Herbert Benson performed a "Study of the Therapeutic Effects of Intercessory Prayer (STEP)" in 2006. The STEP, commonly called the "Templeton Foundation prayer study" or "Great Prayer Experiment", used 1,802 coronary artery bypass surgery patients at six hospitals. Using double-blind protocols, patients were randomized into three groups, individual prayer receptiveness was not measured. The members of the experimental and control Groups 1 and 2 were informed they might or might not receive prayers, and only Group 1 received prayers. Group 3, which served as a test for possible psychosomatic effects, was informed they would receive prayers and subsequently did. Unlike some other studies, STEP attempted to standardize the prayer method. Only first names and last initial for patients were provided and no photographs were supplied. The congregations of three Christian churches who prayed for the patients "were allowed to pray in their own manner, but they were instructed to include the following phrase in their prayers: 'for a successful surgery with a quick, healthy recovery and no complications'. Some participants complained that this mechanical way they were told to pray as part of the experiment was unusual for them. Major complications and thirty-day mortality occurred in 52 percent of those who received prayer (Group 1), 51 percent of those who did not receive it (Group 2), and 59 percent of patients who knew they would receive prayers (Group 3). Some prayed-for patients fared worse than those who did not receive prayers. In The God Delusion, evolutionary biologist Richard Dawkins wrote, "It seems more probable that those patients who knew they were being prayed for suffered additional stress in consequence: 'performance anxiety', as the experimenters put it. Dr Charles Bethea, one of the researchers, said, 'It may have made them uncertain, wondering am I so sick they had to call in their prayer team?'" Study co-author Jeffery Dusek stated that: "Each study builds on others, and STEP advanced the design beyond what had been previously done. The findings, however, could well be due to the study limitations." Team leader Benson stated that STEP was not the last word on the effects of intercessory prayer and that questions raised by the study will require additional answers.
A meta-analysis of several studies related to distant intercessory healing was published in the Annals of Internal Medicine in 2000. The authors analyzed 23 trials of 2,774 patients. Five of the trials were for prayer as the distant healing method, 11 were with noncontact touch, and 7 were other forms. Of these trials, 13 showed statistically significant beneficial treatment results, 9 showed no effect, and 1 showed a negative result. The authors concluded that it is difficult to draw conclusions regarding distant healing and suggested further studies.
A 2003 levels of evidence review found "some" evidence for the hypothesis that "Being prayed for improves physical recovery from acute illness". It concluded that although "a number of studies" have tested this hypothesis, "only three have sufficient rigor for review here" (Byrd 1988, Harris et al. 1999, and Sicher et al. 1998). In all three, "the strongest findings were for the variables that were evaluated most subjectively. This raises concerns about the possible inadvertent unmasking of the outcomes assessors. Moreover, the absence of a clearly plausible biological mechanism by which such a treatment could influence hard medical outcome results in the inclination to be skeptical of results." This 2003 review was performed before the 2005 MANTRA study and the 2006 STEP project, neither of which were conclusive in establishing the efficacy of prayer.
Various, broader meta-studies of the literature in the field have been performed showing evidence only for no effect or a potentially small effect.. For instance, a 2006 meta analysis on 14 studies concluded that "There is no scientifically discernable effect for intercessory prayer as assessed in controlled studies". However, a 2007 systemic review of 17 intercessory prayer studies found "small, but significant, effect sizes for the use of intercessory prayer" in 7 studies, but "prayer was unassociated with positive improvement in the condition of client" in the other 10, concluding that based upon the American Psychology Association's Division 12 (clinical psychology) criteria for evidence-based practice, intercessory prayer "must be classified as an experimental intervention." The review noted that the most methodologically rigorous studies had failed to produce significant findings.
- K. Masters, G. Spielmans, J. Goodson "Are there demonstrable effects of distant intercessory prayer? A meta-analytic review." Annals of Behavioral Medicine 2006 Aug;32(1):21-6. 
- David R. Hodge, "A Systematic Review of the Empirical Literature on Intercessory Prayer" in Research on Social Work Practice March 2007 vol. 17 no. 2 174-187 doi:10.1177/1049731506296170 Article abstract Full length article
- Boorstein, Michelle. Researchers Stepping Up Study of Health And Religiosity, Washington Post, 6 December 2008.
- Francis Galton, Statistical Inquiries into the Efficacy of Prayer, The Fortnightly Review, August 1, 1872 (from abelard.org)
- Richard Dawkins, 2006, "The God Delusion", Bantam Press: ISBN 0-618-68000-4, p. 61.
- Byrd RC (July 1988). "Positive therapeutic effects of intercessory prayer in a coronary care unit population". Southern Medical Journal 81 (7): 826–9. doi:10.1097/00007611-198807000-00005. PMID 3393937.
- Chamberlain and Hall 2001, 34
- Complementary Therapies in Rehabilitation: Evidence for Efficacy in Therapy by Carol M. Davis 2008 ISBN 1-55642-866-9 page 363
- Harris WS, Gowda M, Kolb JW et al. (October 1999). "A randomized, controlled trial of the effects of remote, intercessory prayer on outcomes in patients admitted to the coronary care unit". Archives of Internal Medicine 159 (19): 2273–8. doi:10.1001/archinte.159.19.2273. PMID 10547166.
- Harris et al. 1999, 2273
- Tessman I, Tessman J (March–April 2000). "Efficacy of Prayer: A Critical Examination of Claims". Skeptical Inquirer 24 (2): 31–3. ISSN 1940-6703.
- Richard P. Sloan, 2006, Blind Faith: The Unholy Alliance of Religion and Medicine, St. Martin's Press, p. 172.
- O'Laoire S (November 1997). "An experimental study of the effects of distant, intercessory prayer on self-esteem, anxiety, and depression". Alternative Therapies in Health and Medicine 3 (6): 38–53. PMID 9375429.
- Sicher, F; Targ, E, Moore D, 2nd, Smith, HS (December 1998). "A randomized double-blind study of the effect of distant healing in a population with advanced AIDS. Report of a small scale study.". The Western journal of medicine 169 (6): 356–63. PMC 1305403. PMID 9866433.
- Textbook of Integrative Mental Health Care by James Lake 2006 ISBN 1-58890-299-4 page 112
- Handbook of Complementary and Alternative Therapies in Mental Health edited by Scott Shannon 2001 Academic Press ISBN 0-12-638281-6 page 259
- Aviles JM, Whelan SE, Hernke DA et al. (December 2001). "Intercessory prayer and cardiovascular disease progression in a coronary care unit population: a randomized controlled trial". Mayo Clinic Proceedings 76 (12): 1192–8. doi:10.4065/76.12.1192. PMID 11761499.
- Cha KY, Wirth DP, Lobo RA (2001). "Does prayer influence the success of in vitro fertilization–embryo transfer? report of a masked, randomized trial". J Reprod Med 46 (9): 781–787. PMID 11584476. (The journal has removed the paper from its site, but is available here; the name of Lobo was also retracted from Pubmed)
- Eisner R (2001). "Prayer may influence in vitro fertilization success". Columbia News. (This document was removed from the site after 2 years)
- Flamm BL (2005). "Prayer and the success of IVF.". J Reprod Med 50 (1): 71. PMID 15730180.
- Flamm B (2004). "The Columbia University ‘Miracle’ study: flawed and fraud". Skeptical Inquirer 28 (5).
- Flamm B (2005). "The bizarre Columbia University ‘Miracle’ saga continues". Skeptical Inquirer 29 (2).
- Leibovici L (2001). "Effects of remote, retroactive intercessory prayer on outcomes in patients with bloodstream infection: randomised controlled trial". BMJ 323 (7327): 1450–1. doi:10.1136/bmj.323.7327.1450. PMC 61047. PMID 11751349.
- Thornett AM (April 2002). "Effect of retroactive intercessory prayer. Cautious approach is needed". BMJ 324 (7344): 1037; author reply 1038–9. doi:10.1136/bmj.324.7344.1037. PMC 1122963. PMID 11976252.
- Bishop JP, Stenger VJ (December 2004). "Retroactive prayer: lots of history, not much mystery, and no science". BMJ 329 (7480): 1444–6. doi:10.1136/bmj.329.7480.1444. PMC 535973. PMID 15604179.
- Krucoff MW, Crater SW, Gallup D et al. (2005). "Music, imagery, touch, and prayer as adjuncts to interventional cardiac care: the Monitoring and Actualisation of Noetic Trainings (MANTRA) II randomised study". Lancet 366 (9481): 211–7. doi:10.1016/S0140-6736(05)66910-3. PMID 16023511.
- Benson H, Dusek JA, Sherwood JB et al. (April 2006). "Study of the Therapeutic Effects of Intercessory Prayer (STEP) in cardiac bypass patients: a multicenter randomized trial of uncertainty and certainty of receiving intercessory prayer". American Heart Journal 151 (4): 934–42. doi:10.1016/j.ahj.2005.05.028. PMID 16569567. Lay summary (PDF) – John Templeton Foundation (April 5, 2006).
- Shermer, Michael (April 5, 2006). "Prayer & Healing: The Verdict is in and the Results are Null". ESkeptic. ISSN 1556-5696.
- Richard Dawkins (2006). "The Great Prayer Experiment". The God Delusion. Houghton Mifflin Harcourt. pp. 87–88.
- Harvard Medical School News Release
- Harvard Gazette April 6, 2006 
- John A. Astin, et al. The Efficacy of "Distant Healing" A Systematic Review of Randomized Trials Annals of Internal Medicine June 6, 2000 vol. 132 no. 11 903-910 
- Powell LH, Shahabi L, Thoresen CE (January 2003). "Religion and spirituality. Linkages to physical health". The American Psychologist 58 (1): 36–52. doi:10.1037/0003-066X.58.1.36. PMID 12674817.
- Richard Dawkins, "The great prayer experiment", in The God Delusion, Black Swan, 2007 (ISBN 978-0-552-77429-1).