The placebo effect grows stronger

It’s getting more difficult for new painkilling drugs to be approved because the rate of effectiveness vs. placebos in drug tests is falling. But oddly, the drop is only being seen in the US.

Based on patients’ ratings of their pain, the effect of trialled drugs in relieving symptoms stayed the same over the 23-year period — but placebo responses rose. In 1996, patients in clinical trials reported that drugs relieved their pain by 27% more than did a placebo. But by 2013, that gap had slipped to just 9%. The phenomenon is driven by 35 US trials; among trials in Europe, Asia and elsewhere, there was no significant change in placebo responses. The analysis is in press in the journal Pain.

(via @tomstandage)

• drugs
• medicine
• science