Effects of remote, retroactive intercessory prayer on outcomes in patients with bloodstream infection: randomised controlled trial

Editors:

I am a Saturday morning surfer with a Ph.D. in Economics who manages
risk on a large portfolio of small business loans. As such, I build
statistical models every day, using them to make bets that materially
affect my and my family's well-being.

My prior belief, having read the literature on scientific evidence
for paranormal effects, is that prayer could work, including
retroactively. However, the method and results of this study were not
satisfying.

First, the p values were indeed weak (I routinely require p<.001
in models I'm betting on). Second, a replication would have been
convincing--not on the same patient group with a different outcome, which
contradicts any reasonable hypothesis of the underlying physics, but with
another group of patients, outcomes, and prayers.

I encourage BMJ to continue to publish well-constructed studies of
paranormal healing "effects" or synchronicities.

Elliott Middleton, Ph.D.

Competing interests:  
None declared

I wonder if any particular God or gods are more effective when
involved in intercessory prayer than others. Since it seems possible to
pray retroactively, might it be be a good idea to include gods that people
used to worship, though almost nobody believes in any more, such as Greek,
Norse gods etc.?

Has anyone tested an obvious control test of praying to 'the
invisible purple unicorn' or similar known-to-be imaginary being ?
Presumably it would be necessary to compare this against prayer to a
living person (not a god).

What format did the prayer take ? Shouldn't a group have short non-
prayers be said for them (e.g. reading from the back of a packet of
cornflakes). I like the line - "There was no sham intervention.".

To be honest if I thought I was in a hospital where people were
praying for me, I'd want to get out of there pretty quickly too, so I'm
not suprised at the outcome !

(I have had a look at the other papers published in that issue of BMJ
and have taken the requisite dose of salt).

Jo

Competing interest : member of the National Secular Society, UK

The purpose of the BMJ piece was to ask the reader the following
question: Given a 'study' that looks methodologically correct, but tests
something that is completely out of our frame (or model) of the physical
world (e.g., retroactive intervention or badly distilled water for asthma)
would you believe in it?

There are three ways to deal with this question:

1. To answer in the affirmative. But this leads to such paradoxes (some
described by the responders to this article) that it is incompatible with
our scientific work, or even with our daily life.

2. To look for methodological or statistical faults. Here an obvious one
was that the duration of fever and the duration of hospital stay are
related. But what if the next 'study' will sport perfect methodology and
statistics?

3. To deny from the beginning that empirical methods can be applied to
questions that are completely outside our scientific model of the physical
world. Or in a more formal way, if the pre-trial probability is
infinitesimally low, the results of the trial will not really change it,
and the trial should not be performed. This is what, to my mind, turns the
BMJ piece into a 'non-study' although the details provided in the
publication (randomization done only once, statement of a wish, analysis,
etc.) are correct.

The article has nothing to do with religion. I believe that prayer is a
real comfort and help to a believer. I do not believe it should be tested
in controlled trials.

The wealth of responses you have had to Prof Leibovici's paper
suggests that not everyone regards it as a hoax. There is therefore some
justification for looking at the study more closely.

It is an essential feature of randomised trials that they can be
replicated. For prospective studies this involves a further set of
subjects; but in a retrospective study of a retroactive effect there is no
reason not to replicate the study by randomising the population again and
repeating the prayers by either the same or a different person. If the
results were consistent on a number of occasions this would enhance their
credibility.

However, it is not necessary to put Prof Leibovici to the trouble of
repeating the experiment because a little further thought shows that it
cannot give a meaningful result.

If a population of 3393 subjects is randomised into two groups on n
occasions, the probability (p) of any subject being placed in only one of
the groups is (0.5)^n; and the probability that the subject falls into
both groups is therefore (1-p). The probability that all 3393 subjects
fall into both groups is (1-p)^3393 and the probability that any one
subject does not fall into both groups (q) is 1-(1-p)^3393.

For n=20 q= .00323 or 1/310

For n=30 q= .0000031 or 1/323,237

For n=40 q falls below the limits of my calculator!

Thus, quite modest numbers of repeat randomisations show that no
meaningful result is possible because all subjects occur in both groups.
If this were not to be the case, then the randomisation is faulty and the
study fails on that account.

A retrospective randomised study simply cannot answer the question
that Prof Leibovici is posing. This says nothing, one way or the other,
about the efficacy of prayer.