Distant healing: two new systematic reviews and meta-analyses

Distant healing is one of the most bizarre yet popular forms of alternative medicine. Healers claim they can transmit ‘healing energy’ towards patients to enable them to heal themselves. There have been many trials testing the effectiveness of the method, and the general consensus amongst critical thinkers is that all variations of ‘energy healing’ rely entirely on a placebo response. A recent and widely publicised paper seems to challenge this view.

This article has, according to its authors, two aims. Firstly it reviews healing studies that involved biological systems other than ‘whole’ humans (e.g., studies of plants or cell cultures) that were less susceptible to placebo-like effects. Secondly, it presents a systematic review of clinical trials on human patients receiving distant healing.

All the included studies examined the effects upon a biological system of the explicit intention to improve the wellbeing of that target; 49 non-whole human studies and 57 whole human studies were included.

The combined weighted effect size for non-whole human studies yielded a highly significant (r = 0.258) result in favour of distant healing. However, outcomes were heterogeneous and correlated with blind ratings of study quality; 22 studies that met minimum quality thresholds gave a reduced but still significant weighted r of 0.115.

Whole human studies yielded a small but significant effect size of r = .203. Outcomes were again heterogeneous, and correlated with methodological quality ratings; 27 studies that met threshold quality levels gave an r = .224.

From these findings, the authors drew the following conclusions: Results suggest that subjects in the active condition exhibit a significant improvement in wellbeing relative to control subjects under circumstances that do not seem to be susceptible to placebo and expectancy effects. Findings with the whole human database suggests that the effect is not dependent upon the previous inclusion of suspect studies and is robust enough to accommodate some high profile failures to replicate. Both databases show problems with heterogeneity and with study quality and recommendations are made for necessary standards for future replication attempts.

In a press release, the authors warned: the data need to be treated with some caution in view of the poor quality of many studies and the negative publishing bias; however, our results do show a significant effect of healing intention on both human and non-human living systems (where expectation and placebo effects cannot be the cause), indicating that healing intention can be of value.

My thoughts on this article are not very complimentary, I am afraid. The problems are, it seems to me, too numerous to discuss in detail:

• The article is written such that it is exceedingly difficult to make sense of it.
• It was published in a journal which is not exactly known for its cutting edge science; this may seem a petty point but I think it is nevertheless important: if distant healing works, we are confronted with a revolution in the understanding of nature – and surely such a finding should not be buried in a journal that hardly anyone reads.
• The authors seem embarrassingly inexperienced in conducting and publishing systematic reviews.
• There is very little (self-) critical input in the write-up.
• A critical attitude is necessary, as the primary studies tend to be by evangelic believers in and amateur enthusiasts of healing.
• The article has no data table where the reader might learn the details about the primary studies included in the review.
• It also has no table to inform us in sufficient detail about the quality assessment of the included trials.
• It seems to me that some published studies of distant healing are missing.
• The authors ignored all studies that were not published in English.
• The method section lacks detail, and it would therefore be impossible to conduct an independent replication.
• Even if one ignored all the above problems, the effect sizes are small and would not be clinically important.
• The research was sponsored by the ‘Confederation of Healing Organisations’ and some of the comments look as though the sponsor had a strong influence on the phraseology of the article.

Given these reservations, my conclusion from an analysis of the primary studies of distant healing would be dramatically different from the one published by the authors: DESPITE A SIZABLE AMOUNT OF PRIMARY STUDIES ON THE SUBJECT, THE EFFECTIVENESS OF DISTANT HEALING REMAINS UNPROVEN. AS THIS THERAPY IS BAR OF ANY BIOLOGICAL PLAUSIBILITY, FURTHER RESEARCH IN THIS AREA SEEMS NOT WARRANTED.