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Drug companies have a problem: they are finding it ever harder to get painkillers through clinical trials. But this isn't necessarily because the drugs are getting worse. An extensive analysis of trial data1 has found that responses to sham treatments have become stronger over time, making it harder to prove a drug’s advantage over placebo.
The change in reponse to placebo treatments for pain, discovered by researchers in Canada, holds true only for US clinical trials. "We were absolutely floored when we found out," says Jeffrey Mogil, who directs the pain-genetics lab at McGill University in Montreal and led the analysis. Simply being in a US trial and receiving sham treatment now seems to relieve pain almost as effectively as many promising new drugs. Mogil thinks that as US trials get longer, larger and more expensive, they may be enhancing participants’ expectations of their effectiveness.
Stronger placebo responses have already been reported for trials of antidepressants and antipsychotics2, 3, triggering debate over whether growing placebo effects are seen in pain trials too. To find out, Mogil and his colleagues examined 84 clinical trials of drugs for the treatment of chronic neuropathic pain (pain which affects the nervous system) published between 1990 and 2013.
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 reponses.The analysis is in press in the journal Pain1.
Read more here. (Nature)
The change in reponse to placebo treatments for pain, discovered by researchers in Canada, holds true only for US clinical trials. "We were absolutely floored when we found out," says Jeffrey Mogil, who directs the pain-genetics lab at McGill University in Montreal and led the analysis. Simply being in a US trial and receiving sham treatment now seems to relieve pain almost as effectively as many promising new drugs. Mogil thinks that as US trials get longer, larger and more expensive, they may be enhancing participants’ expectations of their effectiveness.
Stronger placebo responses have already been reported for trials of antidepressants and antipsychotics2, 3, triggering debate over whether growing placebo effects are seen in pain trials too. To find out, Mogil and his colleagues examined 84 clinical trials of drugs for the treatment of chronic neuropathic pain (pain which affects the nervous system) published between 1990 and 2013.
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 reponses.The analysis is in press in the journal Pain1.
Read more here. (Nature)
