Evidence based medicine. Blind but not in a good way

Imagine you had bought a new house but after a few months the flow of water from the taps began to slow and within a few weeks it was down to a trickle. So you call the builders and they say, no worries, Evidence Based Plumbing Services will be with you within the hour.

A large van soon arrives and several men start unloading lengths of plastic tubing. “Going to have to re-plumb your system sir” says the foreman.

“But it’s a new house,” you cry. “I only moved in three months ago. “How can it need a new plumbing system?”

“Don’t worry sir, this is the best evidence-based replacement system there is,” he replies. “We have two randomised controlled trials that ran for ten years and found it was 20 times better than the placebo pipes and totally safe.”

“But you haven’t even checked to see what’s wrong. I saw on the internet that it could be caused by a mineral build up in the pipes and that an alkaline solution could clear it.”

“Dear me sir, never trust the internet. I’m afraid there is no good evidence that clearing blockages works sir. There are only a few small trials and the results are contradictory.”

“So why don’t you run a big trial on it. If it worked would save a lot of time and money.

“We’ve offered to sir but no one will pay for one. There’s no money in solutions that clear blockages.”

“And there is in replacement plastic pipes I suppose?”

“Oh yes sir, lots. That’ll be £5000 please.”

 Diet cuts diabetes by 58 percent

This bit of whimsy was prompted by discovering an old research folder of mine from 2003 about the emerging diabetes epidemic and what to do about it. At the time the number of cases of diabetes in the USA was estimated at 16 million. The options were diet and lifestyle, new drugs and targeting diabetes linked genes.

A paper from the journal Science explained the epidemic was being driven by obesity fuelled by an ample food supply and lifestyle, and reported a study showing that: “intensive lifestyle counselling could reduce the incidence of 58 per cent.” It also said that at least a dozen genes were linked with the disease and could provide good targets for anti-diabetic drugs.

Another Science paper around the same time also favoured life style, reporting that “modifiable behavioural factors” accounted for over 90 per cent of the risk in type 2 diabetes. It warned that “preventative strategies (for diabetes) are heavily biased toward pharmacology ….rather than diet and life style that could be more cost-effective”. A third from Science warned that the emphasis on searching for genes that would be suitable drug targets was too simplistic and was “being questioned by many scientists” because it largely ignored the complexity of cell activity.

 The blue sky bet

So based on that sort of data, and there were plenty of other studies and findings on the same lines, what would have been a rational strategy for tackling the epidemic? Maybe 25% on genetics? Unlikely to do much in the short-term but the blue sky bet. Then 25% on drugs? They didn’t prevent it, didn’t cut the risk of heart problem but there might be improvement and some people would never respond to lifestyle approach.

But given that this was a crisis and that diet and lifestyle could produce results quickly and that it had good evidence backing it up, it was a no brainer to spend half the money there.

A curiously blind system

But of course that never happened and ten years later here we are with the number of diabetics in American up to 26 million according to the American Centres for Disease Control. We have a couple of new classes of drugs – the GLP-analogues and the DP-4 inhibitors – that don’t put on weight like earlier drugs that but still have no proven effect on cardiovascular risk and the long term side-effect are unclear.

Despite massive spending genetic research has, predictably, contributed nothing practical. A major study in 2010 discovered 12 more diabetes genes, bringing the total to 38. But since together they all only account for an estimated 10% of cases, the report admitted the finding was: “unlikely to have any immediate implication for screening or prevention of type 2 diabetes.”

So using the drugs is indeed evidence based but we have hitched ourselves to a curiously blind system for assessing what kind of treatments to invest in when it produces such an obviously wrong-headed strategy for dealing with a  major health crisis.


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