Some honesty about honest placebos

Placebo’s reputation for being “powerful” is exaggerated in many ways. One of the most obvious examples in the last decade is the claim that placebo works even when you tell people what’s going on — “take this fake medicine!” This an open-label or non-deceptive placebo, or just call it an honest placebo.

Sobering science is lagging behind the honest-placebo hype, but it is at least happening. Back in 2019, Kleine-Borgmann et al reported that prescribing an honest placebo for back pain was more helpful than typical care. Three years later, they had important follow-up: they have now also reported that the benefit did not last, that the data “do not support the previously suggested assumption that a three-week open-label placebo treatment has long-term effects.”

Not a surprise. As the authors note, “research on non-deceptive placebos is still in its early stages, and studies on long-term effects are almost nonexistent.” They present their findings primarily in contrast to the only other data of this kind: Carvalho et al’s rather startling 2021 conclusion that the benefits of their honest placebo were sustained for five years, which got placebo fans quite overheated. Those researchers did acknowledge a major methodological limitation, but it was more pointedly described by Kleine-Borgmann et al. (and I will translate this monster of a sentence):

“…because of a predefined crossover from treatment-as-usual to open-label placebo, in which all patients received OLP at the end of the study, follow-up was performed as an observational analysis without a control group, preventing causal attribution of continued improvements to OLP treatment.”

Er, say what now? That translation then: all the subjects in the Carvalho study got open-label placebo in the end, so ultimately the study was not a controlled trial, not a comparison, and so not very persuasive.

Most data has some utility, but some of it has a lot less than others, and arguably there was no point in studying honest placebo this way in the first place. Carvalho’s sensational findings of super durable benefits from non-deceptive placebo never deserved to be a sensation; they were probably just an artifact. I suspected that all along, but “I’ve got a bad feeling about this data” doesn’t make for a very convincing footnote.

So it’s nice that those too-good-to-be-true results are now directly contradicted by a newer, better study. Die, placebo hype, die!

Read more about the whole honest placebo thing.