Evil Twins

Evil Twins

I recently discussed the number needed to harm, the evil twin to the number needed to treat.

The evil twin of the placebo effect is the nocebo effect, when you give an inert substance and get an adverse reaction. Note that is different than a side effect. I give a patient penicillin and they get a rash, that is a side effect. I give them a product with no effect and they get a complication, that is a nocebo effect.

A nocebo (Latin for “I will harm”) is something that should be ineffective but which causes symptoms of ill health. A nocebo effect is an ill effect caused by the suggestion or belief that something is harmful.

It is why I was amused by Clinically meaningful nocebo effect occurs in acupuncture treatment: a systematic review.

To have a nocebo effect you, in essence, admit that acupuncture has no real effects, that it is inert. About time.

And they found in a systematic review of 58 trials that

The nocebo effect was 0.049 (95% CI: 0.012, 0.086), with an NNH of 20 (95% CI: 12, 83),

A number needed to harm of twenty for a intervention that is inert is pretty toxic, much worse than the NNH reported with NSAIDs, the go to bogeymen of the alternative medicine proponents.

What’s the harm? is a common question with worthless pseudo-medicines like acupuncture.  Nocebo is part of the harm and a common harm:

Our findings suggest that (1) the nocebo effect of acupuncture is clinically meaningful.

More data that acupuncture, besides being useless, is harmful.

References

J Clin Epidemiol. 2014 Apr 25. pii: S0895–4356(14)00089–4. doi: 10.1016/j.jclinepi.2014.02.021. [Epub ahead of print] Clinically meaningful nocebo effect occurs in acupuncture treatment: a systematic review.

Battling Placebos, Wrong Conclusions
Points of Interest: 05/02/2014