Adverse effects of drugs are “neglected, restricted, distorted and silenced”

Posted By _Dr John Briffa_ On October 30, 2009 @ 11:50 am In _Food and
Medical Politics_ _
<http://www.drbriffa.com/blog/2009/10/30/adverse-effects-of-drugs-are-neglected-restricted-distorted-and-silenced/print/#comments_controls>_

When someone takes a medicine, it is generally in the hope that it will
do some good. However, whether it does or doesn't is only half of the
story: even the seemingly most innocuous of drugs can have adverse
effects on health. In an editorial in the Archives of Internal Medicine,
Dr John Ioannidis of University of Ioannina School of Medicine in
Greece, makes the point that adverse effects from drugs are "neglected,
restricted, distorted, and silenced" [1].

Dr Ioannidis' editorial starts by making the point that new drugs often
offer little in the way of benefit over existing treatments. This means
that knowledge of their risk profile is essential to be able to make
informed choices regarding therapy.

The editorial focuses on an analysis of relevant studies which appears
in the same edition of the journal [2]. In this analysis 133 studies
published in 'high-impact' journals (the most widely-read and respected
journals) were assessed in terms of the adverse effect reporting. This
analysis showed that "some trials gave absolutely no information on
harms, severity was often undefined or vaguely defined, and half the
trials reported no information on withdrawal of patients owing to harms.
Only 13% reported the reasons why patients withdrew owing to adverse
events, information that is of prime clinical relevance."

Dr Ioannidis also makes the point some trials limit their reporting of
adverse effects to 'statistically significant' results. The problem is,
the most serious adverse effects are generally very rare, and studies
may not be large (powered) enough to define serious adverse effects as
'statistically significant'. Dr Ioannidis claims that the statements
such as "no significant differences were found" are misleading. I made a
similar point some time ago in the blog post [1] here
<http://www.drbriffa.com/blog/2008/05/23/the-limited-value-of-statistical-significance-in-the-real-world/>.

Dr Ioannidis draws our attention to the fact that randomised controlled
trials on drugs are primarily used to assess effectiveness, not risk. He
asks whether this is perhaps the accepted norm as a result of "conflicts
of interest and marketing". Dr Ioannidis ends by suggesting that the
mission of randomised control trials may need to change to include
better understanding of the potential harms of medication.

*References:*

1. Ioannidis JPA. Adverse Events in Randomized Trials: Neglected,
Restricted, Distorted, and Silenced. Arch Intern Med 2009;169(19):1737-1739

2. Pitrou I, et al. Reporting of Safety Results in Published Reports of
Randomized Controlled Trials. Arch Intern Med 2009;169(19):1756-1761

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_____________________________________________________________________________

Norma Bridge
Dip ION, FdSc, mBANT, NTC registered Practitioner
Essentia Nutrition
www.essentianutrition.co.uk
+44 (0)7791 890 541