Category Archives: Pseudoscience

Is global warming causing the increase in the prevalence of diabetes?

diabetes climate change
This is not foot related, but it is diabetes related and science related.

I have no doubts what-so-ever about climate change and global warming. All the science I have seen is good; the consensus of the overwhelming majority of climate change scientists is good. The only dissent to this overwhelming consensus of experts are those with vested financial interests or those into conspiracy theories who latch on one piece of negative evidence (and ignore the 1000’s of good evidence) or latch onto one dissenting scientist (and ignore the 99.5% of the other scientists). How many more generations that we survive on this planet will depend on how seriously the politicians take this scientific evidence that it is happening.

What got me on that hobby horse rant was this study linked the increasing prevalence of diabetes to global warming. My first reaction was going to be negative, but it was published in a quite prestigious open access journal, so I went for a further read.

The authors did a pretty thorough job and were able to show that “Per 1°C increase in temperature, we found an overall increase in age-adjusted diabetes incidence of 0.314 per 1000.“. Fortunately, the authors did say that the nature of the study design means that they can not draw causality. In other words: correlation ≠ causation. It could be that the increasing prevalence of diabetes is causing the global warming and would be interesting to speculate as to a possible mechanism.

Or it could be that the correlation is spurious and there no true relationship, just like this correlation:

or even this one:

For more, see this website.

I have no doubt that global warming is happening and something needs to be done. I have no doubt about the increasing prevalence of diabetes and something needs to be done. I just not convinced of the relationship between them is any more than a correlation.

Blauw, L., Aziz, N., Tannemaat, M., Blauw, C., de Craen, A., Pijl, H., & Rensen, P. (2017). Diabetes incidence and glucose intolerance prevalence increase with higher outdoor temperature BMJ Open Diabetes Research & Care, 5 (1) DOI: 10.1136/bmjdrc-2016-000317

University lecturer, runner, cynic, researcher, skeptic, forum admin, woo basher, clinician, rabble-rouser, blogger, dad. Follow me on Twitter, Facebook and Google+

Homeopathy data dredging

Homeopathy does not work and can not work. The evidence is clear; and there is plenty of that evidence. It is no better than a placebo. Any ‘clinical’ effect of it is due to that placebo effect. I won’t get into it all the details here, but if you want more check this out: How Does Homeopathy work?.

That does not stop those who try to defraud the consumer with homeopathy from grasping at straws and coming up with implausible and improbable mechanisms as to how it might work (it doesn’t) and grasping at some badly done flawed studies published in a low or no impact factor journals, and ignore all the well done properly blinded and controlled studies published in high impact factor journals. And when that argument does not work, they come up with some sob story or special pleading that this is not the appropriate way to clinically test homeopathy (it is).

One way you can get a ‘not quite correct’ result in a clinical trial, is that you just collect a lot of different outcome measures and by chance, one or two of them might be statistically significant, but it is highly likely a result by chance and not due to a real effect. To get around this problem it is now standard practice to register clinical trials in advance and state what your primary endpoint measure is. Almost all major medical journals have for many years now required this a priori registration of clinical trials before they will accept a paper for publication. One of the aims is to prevent the sort of data dredging that could go on until a set of results is found the confirms the preconceived biases of the researchers. The analysis of the data should primarily stick to what was a priori specified and registered.

What drew my attention to this today, was this study that looked at the publication of homeopathy studies registered on ClinicalTrials.gov. After 2 years only just under 50% were published. There could be many reasons for that, but what was of most interest to me in the results was that of those that were published, a quarter altered their primary endpoint from what was in the a priori registration! That should set up big alarm bells. That means they went looking in the data for a better result than what they would have got with the a priori specified endpoint! That is really dodgy and should not pass the ‘sniff’ test, yet still got published.

This sort of nonsense goes on a lot with clinical trials on alternative medicine. I already blogged about how randomized controlled trials on reflexology more often than not end up with the exact same number in each group which is really hard to to if you randomize properly, which means they were not randomizing properly!

I will finish with this cartoon. Those familiar with the nonsensical proposed mechanism of homeopathy working via molecular memory, will appreciate why homeopathy is still full of shit.

University lecturer, runner, cynic, researcher, skeptic, forum admin, woo basher, clinician, rabble-rouser, blogger, dad. Follow me on Twitter, Facebook and Google+