Long term ignorance

Keith Humphreys laments the short term focus of the evidence base for medications.

. . . the evidence base is almost useless for answering questions about the long-term costs and benefits of opioid medications. In the 41 randomized clinical trials that Furlan et al. review, the impact of the medication was evaluated for an average of only 5 weeks. That’s enough to show acute pain relief effects, but leaves us in the dark about what happens to the millions of people who take these medications over longer periods.

None of this is unique to the study of pain medication. Anti-depressants, which are prescribed long-term to tens of millions of people, are typically evaluated in 12 week trials. I suspect experts in cardiology, rheumatology and endocrinology could provide examples in their own areas of medications that are widely prescribed for the long term but only evaluated in the short term.


The primary reason for the short-termism of pharmaceutical research is that much of it is funded by the industry itself. Short-term studies are cheaper and meet the FDA requirements for demonstrating efficacy. If there are long-term problems with a medication a company is developing, it would be economically foolish of them to design a study that would reveal it.

The public of course has a different balance of interests and cares what happens to its health beyond a 5 or 12 week window. But public research money to pursue those interests scientifically is drying up, meaning that we will continue to learn about the long-term effects of many medications only by nervously watching what happens when millions of people take them in the course of receiving health care. That’s no way to protect the public health.

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