Ask a public-health student 2.0

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So let's kick the discussion off with an overview of how evidence is used in public health, with this video I made. The video is boring, dull, and not very nice - in fact it'd almost make a good introductory lecture for future students in that regard! However, despite the poor production quality and presentation style, I've think that I've covered how evidence is applied in public health practice to a satisfactory level.

https://www.youtube.com/watch?v=_psJ52fPiws

The NHMRC guidelines of course can't guide all applications of health work (nor should it for that matter), but it's certainly of importance in matters of health protection where you want to design strategies to reduce the burden of disease on a population overtime, or in identifying and responding to areas of interest that have a particular public health concern, that kind of thing. Certainly things like nutritional guidelines. I'm really surprised by how many people don't think that those guidelines are evidence-based: they are literally based on nothing except evidence - and overviews, and literature reviews, and other published critical analyses of the available evidence, as well as considering professional opinion amongst the relevant experts (i.e. dieticians, and those actively involved in researching and publishing evidence). Of course the example I give in my video is much easier to give an overview of existing evidence than something as complicated as that, and hopefully serves as a good example of how evidence can be applied directly from those NHMRC guidelines to guide clinical practise.

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CLIMATE CHANGE

So I thought about doing a video, and perhaps in the future. But health effects, climate change, and appropriate public health interventional responses. Hmm.

First thing I want to point out is that there are direct and indirect health effects of climate change. But. Are they actually influenced by what happens as a global average of the climate, or would that specific effect (global climate change) have a small or negligible overall effect on the health outcomes associated with regional climate change?

So what evidence is there precisely? Well, there's climate modelling, and expert opinion. There are no RCTs (randomised controlled trials), no level-iii evidence, no level-iv evidence (under NHMRC hierarchy). In matter of public health, expert opinion is considered to be the weakest possible form of evidence, besides anecdotal opinion. And this should be considered when forming public health policies. Now with that said, the modelling does strongly predict shifting weather patterns that have the potential to create climate refugees particularly in places such as Africa where one country's annual rainfall shifting into another's would have profound effects on health. Imagine you live in northern Sudan and your source of water - rainfall - shifts north into Egypt, and that water that was once yours runs into the Mediterranean.

The real problem with this hypothesis is that it's been observed already in ancient civilisations. People have abandoned lands and fled to other regions because of prolonged famine due to insufficient rainfall. It's not a modern phenomena at all. The best possible policy response to the health threats posed by climate change in my opinion are in building stronger inter-national relations between nation-states that share lands spread across regions of the world. That will prevent a possible crisis when it comes to climate refugees, and it'll have plenty of other benefits as well to justify the strategy.

But, as for policies to reduce greenhouse gas emissions: they are either never based on cost-benefit analyses, or they ignore key findings of said reports. It's true there could be a global health benefit from reducing the amount of global warming by reducing GHG emissions. Could be. But, the cost of doing so is astronomical. In fact, as I've pointed out many many times - individual countries such as Australia contribute essentially nothing to the overall trend, even if it's wholly attributed to GHGs (and even less when GHGs are not the only factor driving climate change). And the other thing is that potential health benefits may outweigh the harms that climate change poses as well. That is to say, more CO2 = better agricultural growth = more food, and healthier and greener forests. It is true in public health often the harms of intervention are not directly considered (for example the small number of individuals that have died as a direct result of unsafe vaccinations). If you want to watch my video in the OP take note that the harms of the programme were never evaluated - i.e. the harms of sending people for unneeded colonoscopies - which FYI, 5 people per 1000 have serious complications from. Same thing with medical side-effects of pharmaceuticals, for example Effexor is highly highly addictive; and long-term the harms may well outweigh the benefits. And finally, as I pointed out in the video - resources for public health are finite. To show that action should be taken to reduce GHGs then there needs to be evidence that shows that the cost of that action will produce value for money in health; and on that front it fails miserably. The money would be much better spent on other areas of health such as hospitals.