Reacción a "Reactions: two studies link microbiome changes to chronic fatigue syndrome"

The study seems well conducted and can be considered of good quality. This is supported by the fact that it is published in a prestigious journal.    

That said, there are several things to assess. While it is true that the patients show statistically significant differences, it is debatable whether these are clinically relevant. Is it relevant, for example, that a medication lowers systolic blood pressure by 0.05 mmHg, no matter how statistically significant the difference is because 10,000 patients were included? It is not. But the worst thing is that the dispersion of cases is almost the same in the two groups. In practice, what the authors find does not seem to lead anywhere beyond suggesting that this might be an avenue for further research.   

On the other hand, studies of gut microbiota are very complex to analyse. After years of intensive research, we hardly have practical applications that can be used in the clinic. There are countless articles that associate microbiota patterns with specific pathologies. But for the time being it is not possible to go beyond mere description. Moreover, the findings are not always consistent between laboratories, even if we only take into account the studies of highest quality. These studies are, so to speak, far from standardised.  

Gut microbiota is undoubtedly a very interesting field of study, but for the moment we could say that we are still in the phase of collecting information, not drawing conclusions. There are enormous variations between individuals, linked to many parameters that we hardly know, and it is risky to try to draw conclusions that are of practical use. The authors of these two articles themselves insist that the data do not imply causality, merely correlation. We can ask ourselves: could the differences between patients and groups be due to the fact that patients, because they are unwell, eat a slightly different diet: maybe they eat less meat and more vegetables, for example, or products with probiotics? By the same token, might they have consumed more antibiotics?  

I think this paper does little more than encouraging further research in this field. It seems to be another article out of the dozens that are published every year, merely describing supposed alterations in patients with central sensitivity syndromes. I have been seeing articles along these lines for years, and very rarely do the same authors offer, after a few years, a body of work that builds on the initial findings to establish the aetiopathogenesis [causes and mechanisms] of these syndromes.  

Having said this, let it be clear that this is a welcome study. It may turn out to be the one that will provide a better understanding of the pathogenesis of these diseases. We shall see. But I tend to be cautious, or even skeptical.   

In any case, I don't think it has any short-term implications for patients.