21 February 2018

For the love of evidence

Clinical Evidence Based

An advance over the last three decades has been evidence-based medicine. No longer do we do what we think is best or, heaven forbid, use clinical judgment.

Trials and evidence inform us of best practice. This means everyone always gets ideal care with the system benefiting from cost-benefit analysis as part of best practice guidelines and evidence-based practice.

OK, I am being facetious. However, our desire to go down the path of evidence-based medicine has thrown up some problems, which had not been thought through.

To start with where is there any evidence for any treatment of people over the age of 70 with multiple co-morbidities. Trials are done on pure populations without other medical conditions. Diabetes drugs are not tested on people with ischaemic heart disease or asthma. Most trials exclude smokers or those with any form of cancer.

In general practice these people still need treatment and cannot be excluded because they don’t fit the criteria.

Yet from these trials come guidelines. If they were just that we might not have a problem. But they have morphed into rules, but yet often are simply some form of consensus opinion.

Dr Robert Centor wrote on Med Page Today: “Guidelines can have serious unintended consequences. When we label our opinions as guidelines, we put all physicians in an uncomfortable and even untenable situation.”

There is also the issue of contradictory evidence and that strange phenomenon where the evidence generally seems to favour whoever has paid for the trial.

It is well recognised that positive result trials generate far more coverage and dissemination than negative ones. Yet those which show something doesn’t work are equally as important.

The ORBITA trial found drug eluting stents were no better than medical management in stable angina. Sham surgery was found to be no better than arthroscopic surgery to remove bony spurs and soft tissue damage in shoulder pain. A similar lack of benefit has been found when comparing arthroscopic knee surgery to sham surgery.

So, while at one level we talk about wanting to be evidence based, when the evidence doesn’t suit, we have a tendency to ignore it. The most egregious examples of this are not in clinical medicine, but in public health.

Despite clear evidence that fats in the diet are not associated with adverse health outcomes and that too much refined carbohydrate is, we still have guidelines encouraging people to eat a low-fat diet. This is the same diet which has paralleled an increase in rates of obesity since the early 1980s.

In November lst year, the assistant health minister even appeared in a video put together by, and hosted on a site controlled by, a cereal manufacturer. This advocated eating more grain-based food, based on a report commissioned by, have a guess…

The Cochrane collaboration has a different view of grains. Research shows that a low-carbohydrate diet can potentially reverse type two diabetes. Yet we ignore this and attack those advocating a low-carbohydrate diet.

Possibly the worst example is our refusal to accept that vaping reduces harm from smoking. Public Health England published a review in February. The findings included that switching from smoking to vaping conveys substantial health benefits and that e-cigarettes could be contributing to at least 20,000 new quits per year.

It also found youth smoking was in decline, debunking the gateway theory.

The US National Academy of Science found “conclusive evidence that completely substituting e-cigarettes for combustible tobacco cigarettes reduces users’ exposure to toxicants and carcinogens…”

In Japan, cigarette sales fell 15% in 2017 as smokers switched to non-combustible alternatives. Despite plain packaging and increased tax, the number of smokers in Australia did not decline between 2013 and 2016. Yet we ignore international experience and accuse those who suggest we should offer smokers other than just a “quit or die” approach of being in the pocket of big tobacco.

The UK Government and US Science Academy must have been bought out.

Why does the devotion to evidence collapse when evidence goes against current beliefs? There are many answers, but ideology tops my list.

In 2018, our attachment to “evidence” is flexible. This may not be all bad, but we need to be more honest about it.

Dr Joe Kosterich is a general practitioner based in Perth. You can read more at www.drjoetoday.com

Declaration: Dr Joe Kosterich is an unpaid director of the Australian Tobacco Harm Reduction Association 


 1. https://www.medpagetoday.com/blogs/kevinmd/70849 

2. https://lowninstitute.org/news/stent-benefits-nothing-sham-study-shows/ 

3. http://lowninstitute.org/news/new-study-shows-shoulder-arthroscopy-no-better-sham-surgery/ 

4. https://www.gov.uk/government/news/phe-publishes-independent-expert-e-cigarettes-evidence-review

5. http://www.nationalacademies.org/hmd/reports/2018/public-health-consequences-of-e-cigarettes.aspx 

6. https://www.theaustralian.com.au/national-affairs/health/debatable-surgery-lifts-health-premiums/news-story/4d4c6cda866fdf4fba85e6a7532a33cc 

7. https://www.theaustralian.com.au/national-affairs/health/health-waste-spinal-fusion-added-to-list/news-story/ffba3301b3b78f59a864739e6b3304d9? 

8. http://grainfibre4health.com.au/en_AU/home.html 

9. https://vimeo.com/244773481/e8ebad21a5 

10. https://www.sciencealert.com/very-low-calorie-diet-reverses-type-2-diabetes 

11. https://www.jt.com/media/news/?year=2017&page=6 

12. http://www.cochrane.org/CD005051/VASC_whole-grain-cereals-cardiovascular-disease