[The second and third large, prospective, randomized, double blind studies that pass muster as valid scientific investigations of the effects of prayer on human health.]

The second study that appears to meet the “gold standard” for scientific studies was one entitled “A Randomized, Controlled Trial of the Effects of Remote, Intercessory Prayer on Outcomes in Patients Admitted to the Coronary Care Unit.” It was published in the October 25, 1999 edition of the Archives of Internal Medicine, and the investigators were William S. Harris, Ph.D. plus eight others of the Mid America Heart Institute. The study was done at Saint Luke’s Hospital, Kansas City, Missouri, a private, university-associated hospital.

The investigators stated: ”The purpose of the present study was to attempt to replicate Byrd’s findings by testing the hypothesis that patients who are unknowingly and remotely prayed for by blinded intercessors will experience fewer complications and have a shorter hospital stay than patients not receiving such prayer.” The intercessors, five to pray for each patient (compared to three to seven in Byrd’s study), were to pray for “a speedy recovery with no complications” plus “anything else that seemed appropriate to them.”  1013 patients were randomized, 484 to the prayer group, and 529 to the usual care group. After removal of those patients who spent less than 24 hours in the CCU (prayer was not started until 24 hours after admission), 524 remained in the usual care group and 466 in the prayer group (I’ll mention this high drop-out rate in the prayer group shortly).

A list of events after entry into the study was compiled, much like the one in the Byrd study, but with 34 events instead of the 26 in the Byrd Study. Again, a scheme was devised to evaluate the overall hospital course, a totally new and untested system, but different from the also new and untested one devised by Byrd. The Harris study scheme was called the Mid America Heart Institute-Cardiac Care Unit (MAHI-CCU) Scoring System, and its criteria are presented in “Table 1” of his paper.

The only finding in the Harris study that indicated the prayer group outperformed the control group was in using the MAHI-CCU Scoring System and then only at a probability level of (.04), a figure very close to the cut-off level of (.05).

The Harris study is a much better study than the Byrd study because the number of patients is larger, it appears to be completely blinded, and the degree of religiosity of the investigators appears to be less (although Dr. Harris supposedly supports the idea of “intelligent design”). Nevertheless, scientific investigators have noted flaws: 1) As already noted, the MAHI-CCU Scoring System has never been previously scientifically validated. Without such validation, any result produced by it is subject to question. 2) The much higher dropout rate in the first 24 hours in the prayer group is a very serious criticism of the study. The statistical probability that this finding would appear by chance is (.001), or 1 chance in a 1000, a statistically very significant finding.  This higher dropout rate, since the mortality rate in the two groups was the same, suggests that the prayer group, for unknown reasons, was not quite as ill as the control group since patients discharged within a day often turn out not to have serious problems. If they were a little less ill at the start, we would expect them to have a more favorable course.  3) The conclusions stated in this investigation, as I’ll describe shortly, are not justified by the data.

Positive findings in a scientific study are not considered valid until replicated by independent investigators. So did the Harris study replicate the positive findings of the Byrd study? The answer is a resounding no! In the 6 items in the list of 26 that I previously described in the Byrd study where the prayed for group did better, not one of these items was statistically significant in the Harris study. When the Harris study subjected its data to the same scheme that Byrd had used in his evaluation of the hospital course of the patients (Table 3 in the Byrd study), the Harris study found the difference between the two groups of (.29) was not even close to being statistically significant. The Harris study did replicate the negative findings from the Byrd Study. There was no statistically difference in days in the CCU, days in the hospital, or mortality.

In remarks at the end of the Harris study, the investigators stated: “Our findings support Byrd’s conclusions despite the fact that we could not document an effect of prayer using his scoring system.” This statement is erroneous. Their findings not only don’t support Byrd’s conclusions but directly refute them. How the editorial board that agreed to publish this article allowed this statement to stand is a mystery to me.

The most recent study, and, I believe, the best designed one, was published in the Mayo Clinic Proceedings in December, 2001, and was entitled “Intercessory Prayer and Cardiovascular Disease Progression in a Coronary Care Unit Population: A Randomized Controlled Trial.” This third “gold standard” study should settle the matter once and for all scientifically. The investigators that wrote the study were Jennifer M. Aviles, MD and six others. This trial was done on patients immediately after discharge from the Coronary Care Unit, a time when the intensity of extraneous intercessory praying by family and friends would generally be waning.

Here is their summary of the findings: “Patients and Methods: In this randomized controlled trial conducted between 1997 and 1999, a total of 799 coronary care unit patients were randomized at hospital discharge to the intercessory prayer group or to the control group. … The primary end point after 26 weeks was any of the following: death, cardiac arrest, rehospitalization for cardiovascular disease, coronary revascularization, or an emergency department visit for cardiovascular disease. Patients were divided into a high-group based on the presence of any of 5 risk factors (age > or = 70 years, diabetes mellitus, prior myocardial infarction, cerebrovascular disease, or peripheral vascular disease) or a low-risk group (absence of risk factors) for subsequent primary events.” The investigators summarized their findings as follows: “Conclusions: As delivered in this study, intercessory prayer had no significant effect on medical outcomes after hospitalization in a coronary care unit.” Not even one difference showed up between the control group and the prayed-for group.

The statistical studies from the nineteenth century and the three CCU studies on prayer are quite consistent with the fact that humanity is wasting a huge amount of time on a procedure that simply doesn’t work. Nonetheless, faith in prayer is so pervasive and deeply rooted, you can be sure believers will continue to devise future studies in a desperate effort to confirm their beliefs. But now that you have the scientific information, don’t let the statement that the efficacy of prayer has been proven by scientific studies go unchallenged. It’s simply untrue.

Related Posts:

1. Scientific Conclusion: Prayer Doesn’t Work – Part 1
2. Scientific Evidence on Homosexuality
3. Are Religion and Science Reconciling?
4. Dubious Medical Alternatives
5. Spot the Flaws: Unpacking the Religion Variable

Tags | critical thinking, Religion, Science