Where’s the evidence?

We make no apology for coming back to the subject of evidence again. This is an age of evidence-based medicine. And this makes a lot of sense. There seems little point in doing something unless there is firm evidence that it does some good. It makes a big change from the days when doctors used to advise patients to “Try this, it seems to do good.”

There is a problem with remedies which have been around for a long time. If a drug has been available for many years, its patent will have expired; anyone can make it and it is often very cheap. When drugs like thiazide diuretics were invented, evidence-based medicine had hardly been thought of.

Let’s take an example. There is very little research-based evidence on the best way to convert patients with diabetes from oral therapy on to insulin. The technique has just been handed down from doctor to nurse or vice versa.

The way that research is organised is very strange. Research is often performed more because someone is willing to pay for it rather than because the question posed is one to which we really need to know the answer. This “someone” who is willing to pay for research is often a pharmaceutical company.

If a drug’s patent has lapsed and it costs very little to produce, no-one is going to finance research on its effects. This can sometimes have very curious effects.

Those who have been paying attention may have noticed in the new Hypertension Guidelines that the phrase “thiazide diuretics” has changed into “thiazide-like diuretics”. We are being encouraged to use indapamide or chlortalidone rather than bendroflumethazide. Is this because these more modern drugs are better than low-dose thiazide diuretics at reducing blood pressure and improving end-point outcomes?

Not necessarily.

In fact, we do not know the answer to this question.

What is known is that thiazide-like diuretics do improve end-point outcomes.
What is not known is whether low-dose thiazide diuretics improve end-point outcomes.

In the latter case this uncertainty is not because of doubtful research results. It is only because that the necessary research has not been done: presumably because no-one is prepared to pay for it. 2.5mg of bendroflumethazide taken every day for a month costs Secretary of State for Health, Andrew Lansley MP, well under £1. Research comes expensive and it would take a lot of pills costing less than £1 a month to pay for some meaningful research.

Much research is funded by charitable organisations such as the British Heart Foundation and Diabetes UK. Perhaps it is time for NICE to list, say, 10 important questions that we really need to know the answer to. Research addressing any of these questions would attract funding from government and charitable organisations. Any other research would have to find alternative funding.

No doubt you could think of some topics but here are two for starters:

  1. Do low-dose thiazide diuretics improve end-point outcomes in people with hypertension?
  2. Which drug is best at preventing epileptic attacks?


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