Nonsense. This is a nonblinded, retrospective, uncontrolled experiment with a small sample size, which hasn't been reproduced. On each of these criteria, it's falls on the "less rigorous" side of Evidenced-Based medicine. Only single case studies are lower on the hierarchy. That was where Wehr started, so the hypothesis has made some progression.
Perhaps you should read up a bit about EBM. It is not a system of excluding evidence, but a heuristic technique to suggest best practice, via grading evidence by quality and then applying statistical analysis.
So would it be possible to do such a study blinded? Or randomised? Of course not. We could prospectively attempt one, but that would be confounded by bias. So actually, this is about as good evidence as one could get for this specific hypothesis, on Evidence-Based means. To think that something is not supporting evidence or that evidence that falls lower on the hierarchy can be ignored, is patently incorrect usage of EBM principles. To ignore or denigrate evidence because it is only based on lower tier studies, when higher tier studies are non-existent or impossible to do, is abuse or misapprehension of EBM. This is especially true if done on a priori grounds, such as expecting a larger sample size when the statistical analysis showed it significant regardless - the very purpose of which is to help exclude studies with insufficient data epidemiologically.
This is part of the criticism. By evidenced-based criteria I consider it "very tentative".
EBM can never be 'tentative'. EBM is a deductive method, not an inductive one; so either something is supported, not supported, or there is insufficient data. Nothing is 'tentative'. The whole point of EBM is to try and get around biases and such, which is why the EBM research cycle starts by reducing a query to a form that can be answered via empirically obtained data - reducing thus the hypothesis to an answerable question (incidentally thus it does not use Scientific Method, which at heart is a system of Induction). This is why statistically analysis plays such a large part thereof, to suggest how valid the obtained empiric data actually is. This study does well in that regard.
Guyat et al. defined it in the first place as a Kuhnian paradigm that falls outside the pitfalls of Induction (which is something that some outliers, like the Science-Based Medicine people critique) for exactly these types of studies - those that people are loathe to acknowledge for whatever reason. Certainly more data would be welcome, but what we have is sound and statistically supported as significant, so it would merely either shift the EBM Best Evidence if not supporting it, or confirm it further. EBM doesn't trade in hypotheses but Evidence; so as it stands, EBM can't be 'tentative' for results that failed to show significance statistically - this did though, so is valid evidence, not 'tentative', though lower tier it is true.
Bizarre insult noted. It is you, however, who has been unwilling or unable to evaluate the weaknesses of this article. It is incredibly easy to get false correlations in small sample sizes. Ask any epidemiologist for examples
I have acknowledged the weaknesses. I stated it has no external validity that can be shown for instance; however, its internal validity is not weak. Nor is 43 years of data a 'small sample size', something it only gets in participants - but again, this study is in a very limited type of Bipolar, so that is an expected limitation. It does however pass Epidemiological muster, as its Q values indicate, which you continue to ignore. One can have massive studies, with thousands of participants, whose conclusions can be inconclusive - that is the very reason we do forrest plots and p and q values and the ilk.
Lol. It is your language that's being criticized. Calling this study "definitive" or "conclusive" is rather unscientific given it's scope.
I have been at pains to delineate in what way it is 'definitive' and 'conclusive', but everyone keeps ignoring it. So essentially you are just erecting a Strawman to tilt at. To reiterate, Internally valid and sound, as indicated by its Q values.
I am sorry, but you really are suffering under a whole slew of misunderstandings of EBM practice - unfortunately all too common. It is heuristic, not exclusionary; it is Evidence-based, not about hypothesis, as represented by its statistical usages; lower tier evidence is not ignored if higher tier is not available or impossible to obtain; etc.