Missing the point in Guangzhou 2022

Inspired by Zeng et al 2022.[1]

IF – impact factor
EA – electroacupuncture
MA – manual acupuncture
NPQ – Northwick Park Neck Pain Questionnaire
SF-MPQ – Short-Form McGill Pain Questionnaire
VAS – visual analogue score
PT – pain threshold (in this case electrical pain threshold in skin)
PPT – pressure pain threshold

key to acronyms

I was instantly drawn to this paper in the European Journal of Pain (IF 3.492) because it is from China and involves 4 different methods of ‘missing the point’ in the control groups.

4 different methods of ‘missing the point’

The phrase ‘missing the point’ in the control group is used ironically. It refers literally to missing the correct classical acupuncture points, but also to overlooking the physiology of needling; that is not appreciating that by needling the same muscle to the same depth at say 20mm away from a classical point, the physiological stimulus may be the same. I first used this phrase in print over 20 years ago, but I failed to fully explain the irony,[2] so you could say I also missed the opportunity to make my point.

I am excited that this theme has finally been addressed, and particularly that it has been performed in China, because the idea that acupuncture only works if it is performed in the correct points has been driven by the theories of Chinese medicine but has never been supported by the purely physiological perspective.

This clinical trial used EA in chronic neck pain and compared this real acupuncture intervention with 4 different types of needling controls. The EA was applied for 30 minutes at 2 points in the neck on each side. Both points were close to GV14. SI15 (Jianzhongshu) is 2cun lateral and EX-HN15 (Bailao) is 2cun above and 1cun lateral. The needles were only inserted about 12.5mm (0.5cun) into the points and stimulated at 50Hz with an intensity of 1 to 5mA. That would not be my choice of the theoretically best analgesic treatment, since the needles only just reach muscle, and the high frequency will mainly stimulate a TENS-like effect in the skin.

EA or control acupuncture was applied in 10 sessions over 3 weeks and the patients were followed up at 3 months.

The control groups were as follows:

1. superficial penetration at the real points (SP)
2. deep penetration at non-points 20mm lateral the real points (NADP)
3. superficial penetration at the non-points (NASP)
4. non-penetration (Streitberger needle) at the real points (NP)

Four different outcomes were used: NPQ,[3] SF-MPQ,[4] VAS and PT.

175 patients with chronic neck pain were enrolled and randomised to the 5 parallel arms (35 per group). So, whilst it was a big trial, because of the number of groups, the statistical power was compromised to some degree.

The PT measurement turned out to be entirely useless in distinguishing between the groups, which does not surprise me since it was a measure of skin electrical threshold. It would have been better to measure PPT I suspect.

NPQ and VAS appeared to be most discriminating, with both measures showing highly significant differences between EA and all but one of the control needling conditions… guess which one! Yes, the deep penetration at non-points 20mm away was mostly just as good as EA. This is exactly what I meant by ‘missing the point’ in the control group, of course there is not difference, unless you cheat. Well, I am pleased to say that the data presented in this paper is likely to be authentic.

deep penetration at non-points was just as good as EA

I would have liked to see a deeper insertion for the EA and a low frequency stimulation used. I typically place needles at 3 times the depth they describe here. Other than that, I am pretty happy with this paper, and the 3 month results of the SF-MPQ appear to show the group means distributed in exactly the sequence that might have been predicted based purely on physiology, ie lowest to highest (best to worst) EA, NADP, SP, NASP and NP. I should note that the differences here are not all significant and in the paper they analysed change values in all the scales rather than the absolute values.

I will show you the graphs at the blog webinar, and we can try to glimpse the truth in the data and avoid, as far as possible, the scourge of confirmation bias.

References

1          Zeng D, Yan X, Deng H, et al. Placebo response vary between different types of sham acupuncture: A randomized double-blind trial in neck pain patients. Eur J Pain Published Online First: 7 February 2022. doi:10.1002/ejp.1924

2          Cummings M. Commentary: Controls for acupuncture – can we finally see the light? BMJ 2001;322:1578.

3          Leak AM, Cooper J, Dyer S, et al. The Northwick Park Neck Pain Questionnaire, devised to measure neck pain and disability. Br J Rheumatol 1994;33:469–74. doi:10.1093/rheumatology/33.5.469

4          Melzack R. The short-form McGill Pain Questionnaire. Pain 1987;30:191–7. doi:10.1016/0304-3959(87)91074-8

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Declaration of interests MC