Stimulated by Yu and Kim 2023.[1]
MA – manual acupuncture
key to acronyms
EA – electroacupuncture
SR – systematic review
PWL – paw withdrawal latency
PWT – paw withdrawal threshold
RoB – risk of bias
WMA – Western medical acupuncture
NSAIDs – non-steroidal anti-inflammatory drugs
I have long pondered on the difference between what we see in laboratory research and in clinical practice with acupuncture. The difference that has always seemed so stark for me is in the treatment (or attempted treatment) of acute arthritis. My experience was that MA or EA were both equally ineffective in humans with acute flares of arthritis (usually rheumatoid in my practice). An injection of corticosteroid always seemed to have the upper hand on anything I could do with acupuncture. Yet there seemed to be a lot of laboratory studies on animal models of arthritis that demonstrated effects of MA or EA and examined the mechanisms involved. So, what was I doing wrong?
This SR of animal studies in arthritis caught my eye. Could it answer my question and reveal my acupuncture inadequacy?
It is unusual to see SRs of laboratory research, and this may be the first I have highlighted on the Blog. First of all, I looked at the flow diagram to see how many studies were found – I was expecting that there might be a lot. 118 were found, but only 21 included in the SR. The search was limited to articles in English so it may have sampled only a small proportion of the existing literature. I imagine that there is a lot of such research published in Chinese. Whilst it may only be a small sample, papers published in English language journals are still likely to be of better quality on average. 31 trials were excluded because they used interventions other than MA or EA, and 24 were excluded because they did not include the predefined outcomes of interest to this SR – PWL, PWT, and percentage increase in paw volume.
Next, I noticed the RoB assessment, and was intrigued by an item that was new to me – random housing (performance bias). So, I looked it up. The authors used the Systematic Review Centre for Laboratory Animal Experimentation’s risk of bias tool (SYRCLE’s RoB).[2]
The housing conditions of animals during an experiment, such as lighting, humidity, temperature etc, can influence study outcomes; therefore, random housing of animals is important. It is also import for preventing or reducing the possibility that the animal care givers and investigators can predict the allocation of animals to various intervention groups.
Interestingly, none of the included studies appears to have used or reported on the use of random housing. So, even from a limited sample of probably some of the best acupuncture studies in this area, there is plenty of room for improvement in the methods used.
There are very nice and clear summary tables and diagram in this paper, and I was amused to see the use of ST36 and or GB34 in all but one of the included studies.
Acupuncture increased PWL and PWT, and reduced paw volume. The pooled results for all three outcomes were highly significant; however, there was also a high degree of statistical heterogeneity in all these analyses, along with asymmetry in all the respective funnel plots.
A large number of different mechanisms were investigated by the included studies, but in summary, acupuncture tends to lower pro-inflammatory cytokines and promote mechanisms to reduce inflammation, such as reducing M1 macrophage polarization and increasing regulatory T cell populations.
The authors noted that acupuncture appears to work best in the early stages of arthritis, when EA is used rather than MA, when treatment is ipsilateral rather than contralateral, and when low frequency EA is included in studies of EA. This all makes sense from a WMA perspective, but it does not really help me improve my results in humans. It simply confirms that when I do try to treat acute arthritis my approach is probably adequate.
None of these studies included comparisons with more conventional treatments. These may have been excluded of course, so I searched PubMed. I did not find much. There were some indications that acupuncture may be superior to NSAIDs in acute gouty arthritis,[3] but I could not find the comparison I wanted – a head-to-head comparison between IA corticosteroid and EA. I suspect that EA would not win this contest.
References
1 Yu W-L, Kim S-N. The effect of acupuncture on pain and swelling of arthritis animal models: A systematic review and meta-analysis. Front Genet 2023;14:1153980. doi:10.3389/fgene.2023.1153980
2 Hooijmans CR, Rovers MM, de Vries RBM, et al. SYRCLE’s risk of bias tool for animal studies. BMC Med Res Methodol 2014;14:43. doi:10.1186/1471-2288-14-43
3 Lee WB, Woo SH, Min B-I, et al. Acupuncture for gouty arthritis: a concise report of a systematic and meta-analysis approach. Rheumatology 2013;52:1225–32. doi:10.1093/rheumatology/ket013
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