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Randomised clinical trial: the efficacy of gut-directed hypnotherapy is similar to that of the low FODMAP diet for the treatment of irritable bowel syndrome

PainSci » bibliography » Peters et al 2016

PainSci notes on Peters 2016:

This small trial compared gut-directed hypnotherapy for irritable bowel syndrome to a low FODMAP diet (and a combination) in a few dozen subjects, finding that they were all approximately equally effective — neither amazing nor futile. The most obvious methodological flaw is that it could have been controlled better, but this is not junk science, and it comes from a lab with a good reputation. Although the trial does have a number of common issues, they are not as severe as they are in many other studies. For instance, gut-directed hypnotherapy is not a particularly plausible treatment (which tends to produce statistical significance), but it’s not absurd either. And it might be going a little too far to say that hypnotherapy is “damned” by faint praise here: perhaps it’s just insulted? And so on.

The real story of this study is that it stands alone. There is virtually no other credible evidence on this topic. And yet this study has been used as the basis for a business (see blog post).

Common issues and characteristics relevant to this paper: ?Scientific papers have many common characteristics, flaws, and limitations, and many of these are rarely or never acknowledged in the paper itself, or even by other reviewers. I have reviewed thousands of papers, and described many of these issues literally hundreds of times. Eventually I got sick of repeating myself, and so now I just refer to a list common characteristics, especially flaws. Not every single one of them applies perfectly to every paper, but if something is listed here, it is relevant in some way. Note that in the case of reviews, the issue may apply to the science being reviewed, and not the review itself.

  1. Risk of inadequate statistical power.
  2. A junky or trivial little study that was probably published more to pad someone’s resumé than to actually answer a research question. We are drowning in studies like this, which mostly just muddy the waters with more inadequate data.
  3. Any positive results may be attributable to the low validity of statistical significance when testing highly implausible effects (a complex topic, see Pandolfi).
  4. A high (and possibly unacknowledged) risk of bias and its consequences (p-hacking, etc).
  5. Damned with faint praise — technically positive results (at least partially) that don’t actually impress.

original abstract Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

BACKGROUND: A low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) diet is effective in treating irritable bowel syndrome (IBS).

AIM: To compare the effects of gut-directed hypnotherapy to the low FODMAP diet on gastrointestinal symptoms and psychological indices, and assess additive effects.

METHODS: Irritable bowel syndrome patients were randomised (computer-generated list), to receive hypnotherapy, diet or a combination. Primary end-point: change in overall gastrointestinal symptoms across the three groups from baseline to week 6. Secondary end-points: changes in psychological indices, and the durability of effects over 6 months.

RESULTS: Of 74 participants, 25 received hypnotherapy, 24 diet and 25 combination. There were no demographic differences at baseline across groups. Improvements in overall symptoms were observed from baseline to week 6 for hypnotherapy [mean difference (95% CI): -33 (-41 to -25)], diet [-30 (-42 to -19)] and combination [-36 (-45 to -27)] with no difference across groups (P = 0.67). This represented ≥20 mm improvement on visual analogue scale in 72%, 71% and 72%, respectively. This improvement relative to baseline symptoms was maintained 6 months post-treatment in 74%, 82% and 54%. Individual gastrointestinal symptoms similarly improved. Hypnotherapy resulted in superior improvements on psychological indices with mean change from baseline to 6 months in State Trait Personality Inventory trait anxiety of -4(95% CI -6 to -2) P < 0.0001; -1(-3 to 0.3) P = ns; and 0.3(-2 to 2) P = ns, and in trait depression of -3(-5 to -0.7) P = 0.011; -0.8(-2 to 0.2) P = ns; and 0.6(-2 to 3) P = ns, respectively. Groups improved similarly for QOL (all p ≤ 0.001).

CONCLUSIONS: Durable effects of gut-directed hypnotherapy are similar to those of the low FODMAP diet for relief of gastrointestinal symptoms. Hypnotherapy has superior efficacy to the diet on psychological indices. No additive effects were observed.

This page is part of the PainScience BIBLIOGRAPHY, which contains plain language summaries of thousands of scientific papers & others sources. It’s like a highly specialized blog. A few highlights: