TUESDAY, June 4 (HealthDay News) -- The drugs emerging from
clinical trials in recent years seem less impressive than those
developed in decades gone by, a new review finds.
Looking at more than 300 studies done since 1966, researchers
found that drugs under development these days are less likely to
solidly outperform placebos -- the sugar pills or other inert
substances against which new drugs are tested.
From 1966 to 1990, the average study drug was about four times
as likely to achieve a particular outcome than a placebo. But in
trials done since 2001, drugs were only 36 percent more likely than
placebos to show a desired effect, researchers reported in the June
issue of the journal
The reasons for the "worrisome decline" are not clear, said lead
researcher Dr. Mark Olfson, a professor of clinical psychiatry at
Columbia University in New York City.
But it's possible, he said, that "much of the low-hanging fruit
has already been picked. In other words, many of the
easiest-to-discover effective treatments may have already been
Another possibility, though, is that drugs from days of yore
were not as impressive as they seemed at the time.
Trials done today generally have a more rigorous design, and
they may be producing fewer "spuriously inflated findings" compared
to older clinical trials, Olfson said.
A researcher not involved in the work said the findings are
interesting, but "raise more questions than answers."
"The study is not designed to tell us the causes," said Ted Kaptchuk, an associate professor of medicine at Harvard Medical School, and director of the university's program in placebo studies.
"Are the new drugs in the pipeline just not as good?" Kaptchuk asked. It's not clear. In part, he said, that's because other research has found that people in clinical trials these days are more likely to respond to the placebo compared to people in studies 20 or 30 years ago.
Researchers have dubbed that phenomenon "placebo drift,"
Kaptchuk said, but no one knows what's driving it.
One theory is that today, people in a trial testing an
antidepressant, for example, may go in with strong beliefs about
the effects of those drugs -- whereas people in a trial in 1990 may
Patients in a clinical trial do not know whether they are
receiving a real drug or a placebo. So if someone on a placebo
believes they're getting the real drug and the drug is good, that
could affect how they respond.
Of course, it's not that effective drugs are no longer emerging,
said Jean Slutsky, director of the Center for Outcomes and
Evidence, part of the Agency for Healthcare Research and Quality,
the government agency that funded the study. "There have certainly
been important treatment advances in recent years and we should
expect that to continue," Slutsky said.
Many of today's widely used prescription drugs -- such as
cholesterol-lowering statins and SSRI antidepressants -- were
developed in the 1980s or '90s. Those years also saw some medical
breakthroughs, such as the protease inhibitors that turned HIV
infection into a manageable chronic disease for many.
But other top-selling drugs emerged in the past decade or so,
including the schizophrenia drug Abilify, the reflux medication
Nexium and the antidepressant and pain drug Cymbalta.
It's also not clear from the current findings whether the
decline in drugs' effects exists only in certain areas of medicine
and not in others, Olfson said.
He said the number of studies in different specialties was too
small to make a comparison. For example, only a small percentage of
the 315 trials tested cancer drugs, a field in which researchers
currently are developing high-tech "targeted" drugs they hope will
be more effective and less toxic than older chemo drugs.
Still, Olfson said, his findings suggest that researchers need
to adjust their focus.
Instead of pouring everything into traditional clinical trials
looking for the next blockbuster, he said, researchers also should
do more so-called comparative effectiveness studies, which look at
how existing treatments stack up in the real world.
"In practice, for example, one treatment may turn out to be much more effective than another because many more patients actually take it than the other treatment," Olfson said.
Slutsky agreed that comparative effectiveness studies are
important. That kind of research, she said, "will help illuminate
important distinctions among treatments and help decision-makers
make informed decisions regarding treatments for particular
Kaptchuk said the findings underscore a need to better
understand the placebo effect, including how it may be changing
drugs' apparent performance in clinical trials. And on a broader
level, he said, the results show how complicated scientific
"People tend to think that, you do a scientific experiment and you get certainty," Kaptchuk said. "But it's a lot more complex than that."
Learn more about
clinical trialsfrom the U.S. National Institutes
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