What to think about a negative result in a clinical trial

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When a clinical trial for a new drug fails to show a useful result, that's bad news. If the drug worked, then you'd have something useful (or at least maybe, since many drugs that work turn out to be unsafe, too expensive to manufacture, or otherwise unsatisfactory). But what about a drug that's been on the market for a while, like say glucosamine/chondroitin? If you aren't already taking the drug then this is bad news because you might someday have whatever condition you previously thought the drug treated and it doesn't work then you need to downgrade your estimate of how likely it is that you'll recover.

The one group of people this isn't bad news for is people who are already using the drug. Say you've already got whatever the condition is and you've been taking the drug for a while: this means you've already got a baseline for how well it works for you. If a study that comes out that shows that the drug doesn't work any better than placebo, that's good news for you; you can stop taking the the drug, get the same results, and save some money. So, you're up whatever the price of the drug was.

Obviously, in either case, the situation hasn't really changed. All that's changed is the information you have. And so whether it's good news or bad news is a matter of what information you had before.

3 Comments

Wouldn't you have to at least substitute a placebo for the glucosamine/chondroitin in order to get the same effect you were before?

Actually I am being facetious. Taking a placebo, knowing it is a placebo, probably has no effect. The danger is that once you learn that glucosamine is no better than a placebo, it will stop working. You may have received actual benefit from the placebo effect, and now that is destroyed.

Both Eric and Hal's statements about placebos are based on the assumption that we understand how placebos work, and who they work on. Yet, there is almost no good literature on either.


Ekr says that if you're already taking the drug and it turns out to be a placebo, you can stop. That's only true if you were getting the "average" amount of placebo value. If you are generally placebophilic, or are placebo-sensitive for the disease in question, stopping using the placebo could cause you to get worse.


Hal says "Taking a placebo, knowing it is a placebo, probably has no effect." There is a difference between knowing and believing. If I was told by someone I trust that a drug that I thought was helping me is a placebo, it could have the effect Hal says, but it could also have the effect of me trusting the source of the information less.

I think you guys are confusing placebo effect with spontaneous remission. The reason the placebo does so will _may_ be simply that most people spontaneously stop experiencing the pain.

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