Read the latest HealthWatch newsletter:  Newsletter 116, Summer 2021

Why evidence matters

The 23rd HealthWatch Award was presented to Dr Mark Porter MBE; GP, journalist, media doctor and presenter of BBC Radio 4’s ‘Inside Health’.

Receiving his award at the Medical Society of London, Dr Porter gave an insight into his unique career, and explained that his listeners, readers, and patients are why evidence matters.

‘For me, it’s not about the data, but how it influences clinical practice — what difference is made to the man or woman sitting in front of me in my consulting room.

Like most, I was a naïve young doctor who did what his boss told him, whose boss did what his boss told him because it was what his boss did, and that’s how we based a lot of our practice. It’s been a gradual transition to the importance of evidence, and now, I’m a complete convert.

My job is not to be an expert. It is to put experts into the public domain. It is to ask questions, and to give them the chance to explain the rationale behind evidence-based medicine; what it is and why it matters to the public, so that everybody out there can make an informed decision about their future.

I don’t need to sell evidence to my listeners  they absolutely ‘get it’. Less straightforward is the way that research is reported. It’s hard to see through the veneer of gloss that’s put upon it by the journalists, or the journal, or by the researchers themselves. Press releases from journals ‘big things up’  it’s not surprising that the story gets slightly confused.

Significance is not well understood. I’m not talking about statistical significance here; I’m talking about what difference this finding might make to their lives. If something doubles the chance of you getting something, but your chance of getting something is pretty near zero in the first place, it’s irrelevant.

Terminology is a struggle. I’m hopeful that there will be a third series of ‘Inside Language’, a series with Professor Carl Heneghan and Dr Margaret McCartney looking at terminology, from surrogate markers to t-tests, which has proved popular.

My job is to teach the public to be a little bit sceptical, a little bit cynical about what they read, look for vested interests, understand why something might be, and understand how to ascertain if it’s relevant to them.

But, I do have concerns, and I just want to share a couple of those with you.

The first is the relevance of the data.

As we bow to the altar of evidence-based medicine, sometimes we’re blinded by the light. We need to be critical about the relevance of the data that we’re looking at, in terms of clinicians like me, working at the coalface of the NHS. A lot of that data ends up informing and producing guidelines, and we need to look at how rigidly we adhere to those guidelines when faced with very different individuals.

The vast majority of patients that I see, perhaps 90%, wouldn’t get into a clinical trial because they don’t meet the criteria - yet they’re the patients that we’re treating. Still a large proportion of the data that we’re looking at is coming from on high. We don’t know how relevant it is to the people we’re actually seeing on a day-to-day basis.

An example I use is that of the contraceptive pill. The early explanatory trials show a failure rate of 1 in 300, so if you had 300 women on the pill for a year, one would expect to get pregnant. But in the real world, where trial conditions don’t apply and all sorts of things arise, that failure rate approaches 1 in 10. That’s a huge, huge difference. But it’s the sort of difference that patients can grasp straight away, and suddenly they see the rationale behind long acting contraceptives.

I’d like to see more pragmatic trials  but they’re not the be all and end all, either. I just want to emphasise that the evidence that we’re looking at is not always pertinent to the people that we’re treating.

My second concern is that the selective data is then used to produce the guidelines. I’m all for guidelines. I’m all for best evidence based practice. But I worry about how rigidly we apply it, because of external pressures. We have QOF, prescribing initiatives, pressure to follow published guidance. Even if the guidelines were perfect - how do we know that we’re applying them correctly to the person that’s sitting in front of us?

External pressures mean that guidelines get rigidly applied. They become tramlines. And I think that’s a problem.

I recently met an elderly gentleman with a humeral fracture in a falls clinic. He had diabetes, atrial fibrillation and other conditions, and had felt lightheaded for months. A number of doctors, consultants, had seen him and treated him according to the guidelines. He was taking sixteen different medicines, including six that lowered his blood pressure. I have no doubt that getting blood pressure to target improves outcomes for 1,000, 10,000, 100,000 diabetic patients. But that doesn’t tell me what’s going to happen to the patient sitting in front of me. He could have hit his head, or broken his hip. We could have killed him. That’s something that we need to consider in general practice.

Scepticism doesn’t stop once you have some evidence, or have guidelines.

I don’t have answers. If pushed, I’d like to revert to that basic tenet of clinical practice: Primum non nocere  or, as I say to my patients if in doubt, do nowt.

(Edited transcript)


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