Tuesday, February 5, 2013

The World's Worst Coin Trick?

Ben Goldacre – whose Bad Pharma went on sale today – is fond of using a coin-toss-cheating analogy to describe the problem of "hidden" trials in pharmaceutical clinical research. He uses it in this TED talk:
If it's a coin-toss conspiracy, it's the worst
one in the history of conspiracies.
If I flipped a coin a hundred times, but then withheld the results from you from half of those tosses, I could make it look as if I had a coin that always came up heads. But that wouldn't mean that I had a two-headed coin; that would mean that I was a chancer, and you were an idiot for letting me get away with it. But this is exactly what we blindly tolerate in the whole of evidence-based medicine. 
and in this recent op-ed column in the New York Times:
If I toss a coin, but hide the result every time it comes up tails, it looks as if I always throw heads. You wouldn't tolerate that if we were choosing who should go first in a game of pocket billiards, but in medicine, it’s accepted as the norm. 
I can understand why he likes using this metaphor. It's a striking and concrete illustration of his claim that pharmaceutical companies are suppressing data from clinical trials in an effort to make ineffective drugs appear effective. It also dovetails elegantly, from a rhetorical standpoint, with his frequently-repeated claim that "half of all trials go unpublished" (the reader is left to make the connection, but presumably it's all the tail-flip trials, with negative results, that aren't published).

Like many great metaphors, however, this coin-scam metaphor has the distinct weakness of being completely disconnected from reality.

If we can cheat and hide bad results, why do we have so many public failures? Pharmaceutical headlines in the past year were mostly dominated by a series of high-profile clinical trial failures. Even drugs that showed great promise in phase 2 failed in phase 3 and were discontinued. Less than 20% of drugs that start up in human testing ever make it to market ... and by some accounts it may be less than 10%. Pfizer had a great run of approvals to end 2012, with 4 new drugs approved by the FDA (including Xalkori, the exciting targeted therapy for lung cancer). And yet during that same period, the company discontinued 8 compounds.

Now, this wasn't always the case. Mandatory public registration of all pharma trials didn't begin in the US until 2005, and mandatory public results reporting came later than that. Before then, companies certainly had more leeway to keep results to themselves, with one important exception: the FDA still had the data. If you ran 4 phase 3 trials on a drug, and only 2 of them were positive, you might be able to only publish those 2, but when it came time to bring the drug to market, the regulators who reviewed your NDA report would be looking at the totality of evidence – all 4 trials. And in all likelihood you were going to be rejected.

That was definitely not an ideal situation, but even then it wasn't half as dire as Goldacre's Coin Toss would lead you to believe. The cases of ineffective drugs reaching the US market are extremely rare: if anything, FDA has historically been criticized for being too risk-averse and preventing drugs with only modest efficacy from being approved.

Things are even better now. There are no hidden trials, the degree of rigor (in terms of randomization, blinding, and analysis) has ratcheted up consistently over the last two decades, lots more safety data gets collected along the way, and phase 4 trials are actually being executed and reported in a timely manner. In fact, it is safe to say that medical research has never been as thorough and rigorous as it is today.

That doesn't mean we can’t get better. We can. But the main reason we can is that we got on the path to getting better 20 years ago, and continue to make improvements.

Buying into Goldacre's analogy requires you to completely ignore a massive flood of public evidence to the contrary. That may work for the average TED audience, but it shouldn't be acceptable at the level of rational public discussion.

Of course, Goldacre knows that negative trials are publicized all the time. His point is about publication bias. However, when he makes his point so broadly as to mislead those who are not directly involved in the R&D process, he has clearly stepped out of the realm of thoughtful and valid criticism.

I got my pre-ordered copy of Bad Pharma this morning, and look forward to reading it. I will post some additional thoughts on the book as I get through it. In the meantime,those looking for more can find a good skeptical review of some of Goldacre's data on the Dianthus Medical blog here and here.

[Image: Bad Pharma's Bad Coin courtesy of flikr user timparkinson.]

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