Helen Pearson: What Constitutes Real Medical Evidence?

**Eric Topol** (0:01)
We have a really great podcast today with Helen Pearson. Helen is a terrific journalist, award-winning. In fact, the Journalist of the Year in Europe last year.
This is her second book. She writes features for Nature.
And this book is quite extraordinary. It's called Beyond Belief, how evidence shows what really works. Okay, so that's what we're going to be talking about today. And related matters, not just everything that's in the book. So, Helen, welcome. It's wonderful to have you.

**Helen Pearson** (0:38)
Thank you so much for having me. Yeah, it's great to be here.

**Eric Topol** (0:41)
Well, evidence is the topic I couldn't resist, surely. And I learned a lot from your book, things I didn't know about.
And clearly, as you aptly describe here, we've been going through this evidence revolution, where the demand for better evidence has continued to culminate to where we are today. But on the other hand, we have some anti-forces that we'll talk about that are diminishing or detracting from evidence. So what I wanted to start with is the amazing story that you presented in the book, which I wasn't familiar with the details about Dr. Spock, and how his original book, I think it was 1946, and how he revised one sentence, and as a result, some 54,000 babies died of sudden infant death syndrome before the actual evidence. Is that about the right summary? Could you take us through what really happened there?

**Helen Pearson** (1:41)
Sure. Yeah. It is a really striking story. I opened the book with that because I wanted to illustrate what happens when we don't use evidence with this striking example. So yeah, I've actually got the copy here. My mom sent me her copy of this first book. So Dr. Spock's book, Baby and Child Care, was like this best-selling child care manual and all parents had it. But what happened was in this 1958 issue, which is the one I've got here, he made a small change to the text. Whereas before he'd been advising parents to put their babies down to sleep on their backs, and he switched it and suggested that they put babies to sleep on their fronts. The reasons were a bit, I mean, he basically was speculating saying, if babies on their backs might end up with a flat head or might choke on their own vomit. So there wasn't really any substantial evidence to support this change. Now, to be fair, he wasn't the only one. So this was generally put forward by pediatricians around this time. But because this book had such huge influence, parents did start following this advice. So there was a rise in children sleeping on their fronts. Meanwhile, there was this rather sinister also rise going on in sudden infant death syndrome. And nobody really knew why this was happening. So people were speculating what's causing this rise in SIDS. And what was missing from this conversation and debate was some actual evidence from studies. So eventually, these first good case control studies start coming out about 1968 I think the first one was where obviously what was needed to happen was you need to compare a group of children who've unfortunately died from SIDS with a group of control babies who were very similar in other ways and try and tease out these factors that might be responsible.
And these first studies kind of hinted at a link, but it was hard to see.
But then over time, eventually the weight of evidence built up. And eventually, I mean, I think I said in the book or it's been called elsewhere, that really Dr. Spock's advice was probably one of the most lethal pieces of unsubstantiated advice in the history of child health, because it became clear that front sleeping was associated with increased risk of SIDS.
And the other reason I kind of told this story was because it also illustrates like the power of synthesizing evidence together. So that was like this really big theme in the book, is the sort of how difficult it can be to just take one study. And later on, so at the time, evidence synthesis wasn't really common. And so it was sort of, well, more that at some point there was, there were enough studies to think that this, there was a link and actually the advice only changed in the 1990s. But later on, some researchers went back and said, what happens if we actually synthesize these case control studies together? At what point was there a signal from the evidence that we should have been able to see there was a link between SIDS risk and front sleeping? And actually that would have been clear in 1970 if that had been done. And that's where this figure came from, that if the evidence had been synthesized and acted on at that time, they calculated that about 50,000 children, you know, could have been avoided. And I think that was just in like the US and Australasia so globally, you know, who knows? So it's just this really kind of powerful, you know, tragic cautionary tale of how important it is, not just to do careful studies, but also to synthesize those studies together.