Stimulated by Lee et al 2025.[1]
PC6 – the acupuncture point Pericardium 6
PONV – post-operative nausea and vomiting
TSA – trial sequential analysis
NMA – network meta-analysis
PON – post-operative nausea (incidence)
POV – post-operative vomiting (incidence)
CI – confidence interval– key to acronyms
It has been 10 years since the last update of this Cochrane review,[2] and this is the fourth version with the same lead author – Anna Lee.[1–4]
Essentially, they have all been positive, but there have been inevitable changes over the years. The quantity of data has increased from 26 trials (n=3347) in 2004 to 40 trials (n=4858) in 2009 and 59 trials (n=7667) in 2015 to 77 trials (n=9847) in 2025. The methods have also changed somewhat. We have lost TSA from the last version and added NMA in the latest. I am also pleased to say that we finally gained a ‘C’ in the last 2 versions, P6 became PC6 in 2015, and it has stayed.
I would never complain about a positive Cochrane review of acupuncture, but the focus on a single acupuncture point is rather unique in such reviews and may become problematic in NMA when too many physiologically different interventions are combined in the same node, such as PC6 stimulation or sham.
There were 10 different forms of PC6 stimulation combined in 2 nodes of the NMA – invasive and non-invasive. There were 58 sham groups in total and importantly, these were all included in the same node, whether they were shams for anti-emetics (eg saline injection) or shams for invasive or non-invasive PC6 stimulation. Interestingly, there was no physiological restriction on sham methods as long as they were not applied to PC6. As far as I know, the only shams that were allowed at the PC6 point were the pressure bands without the bead to apply the pressure.
If the shams for anti-emetics were all injections of saline, this is probably not as much of a problem as combining sham acupuncture in the same node (of an NMA) as a placebo pill and hence assuming that they each have the same effect. The latter was famously done for the first time by NICE in CG150. This is discussed several times on the blog archive (just type CG150 into the search box), but the most comprehensive mention comes in this post from September 2019 – Acupuncture vs propranolol in migraine.
As I have already alluded to, the results are positive for PC6 stimulation, and this holds true for PON, POV, and use of rescue anti-emetics.
When ranked in order from best to worst (from NMA data), group E came first followed by group B for both PON and POV. Group E includes invasive PC6 stimulation plus anti-emetics and group B is invasive PC6 stimulation alone. Group D (anti-emetics) were ranked 4th for PON and 5th for POV. Judging by the CIs, B significantly outperformed D in PON. B was also numerically better in POV, but the CIs were somewhat wider, so this would not have been significant.
It is interesting that this comparison between invasive PC6 stimulation (mostly acupuncture) and anti-emetics from the NMA is not mentioned anywhere in the review. Instead, the review comments only on the pairwise comparisons performed in direct meta-analysis, in which the diamond tips just touch the line indicating no difference whilst the trend is firmly in favour of PC6 stimulation.
The previous review also found no difference between PC6 stimulation and antiemetic drugs. It concluded (based on TSA) that further head-to-head research was futile. TSA was dropped in this review due to concerns abouts its reliability in the face of significant heterogeneity. NMA was used for the first time and invasive PC6 stimulation is consistently ranked above antiemetics for both PON and POV, but not for the use of rescue antiemetics, which is of course a rather strange thing to measure against antiemetics in the first place.
On Wednesday evening I will walk you through some of the new aspects and nuances of this latest review including parallelism, incoherence, and net heat plots… I’m sure you can’t wait!
References
1 Lee A, Zhang JZ, Xie J, et al. Stimulation of the wrist acupuncture point PC6 for preventing postoperative nausea and vomiting: a network meta-analysis. Cochrane Database Syst Rev. 2025;9:CD003281. doi: 10.1002/14651858.CD003281.pub5
2 Lee A, Chan SK, Fan LT. Stimulation of the wrist acupuncture point PC6 for preventing postoperative nausea and vomiting. Cochrane Database Syst Rev. 2015;11. doi: 10.1002/14651858.CD003281.pub4
3 Lee A, Fan LT. Stimulation of the wrist acupuncture point P6 for preventing postoperative nausea and vomiting. Cochrane Database Syst Rev. 2009;CD003281. doi: 10.1002/14651858.CD003281.pub3
4 Lee A, Done ML. Stimulation of the wrist acupuncture point P6 for preventing postoperative nausea and vomiting. Cochrane Database Syst Rev. 2004;CD003281. doi: 10.1002/14651858.CD003281.pub2
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