Vagus Nerve Stimulation in the News

There is a lot of
information about href="http://en.wikipedia.org/wiki/Vagus_nerve_stimulation"
rel="tag">vagus nerve stimulation as a treatment
for depression, that you can get from the latest New York Times article
( href="http://www.nytimes.com/2006/09/10/business/yourmoney/10cyber.html?ex=1315540800&en=7877734ab451d64f&ei=5090&partner=rssuserland&emc=rss">Battle
Lines in Treating Depression, permanent link) on the subject.
 Unfortunately, most of the good information is found by
following links.  The article itself is pretty bad.



The author launched into a senseless antipsychiatry screed.
 Despite the title, most of the article is about the
controversial decision by the FDA to approve the Cyberonics vagus nerve
stimulator for treatment of refractory depression.  But the
article includes a lot of other stuff that shows that bad things can
happen when aggressive treatments are attempted.  As a result,
the article is kind of a confusing mishmash with no clear conclusion.



Read it and ponder.  



I suppose I shouldn't complain.  A while back, I started
writing about the rel="tag">Cyberonics device (and deep brain
stimulation of area 25) and turned it into a call for universal health
coverage.  



I suppose we all have out little agendas.

Anyway, the article mentions some criticism of the FDA for approving
the device based upon flimsy evidence.  One complaint I have
about the article is that the topic was not well researched.
 For example, the article makes it clear that the evidence
supporting the efficacy of the device was weak, at the time of the FDA
approval (February 2005).  That is true.  A lot of
observers (myself included) were surprised that the approval was
granted.  

After learning that the initial data were weak, the next thing I would
want to know is this: are any newer data available?  What does
the new information show?  

href="http://www.journals.elsevierhealth.com/periodicals/bps/article/PIIS0006322305006190/abstract">A
One-Year Comparison of Vagus Nerve Stimulation with Treatment as Usual
for Treatment-Resistant Depression

Biological Psychiatry, Volume 58, Issue 5 , 1 September
2005, Pages 364-373



Background

Previous reports have described the effects of vagus nerve stimulation
plus treatment as usual (VNS+TAU) during open trials of patients with
treatment-resistant depression (TRD). To better understand these
effects on long-term outcome, we compared 12-month VNS+TAU outcomes
with those of a comparable TRD group.

Methods

Admission criteria were similar for those receiving VNS+TAU (n = 205)
or only TAU (n = 124). In the primary analysis, repeated-measures
linear regression was used to compare the VNS+TAU group (monthly data)
with the TAU group (quarterly data) according to scores of the 30-item
Inventory of Depressive Symptomatology–Self-Report (IDS-SR30).

Results

The two groups had similar baseline demographic data, psychiatric and
treatment histories, and degrees of treatment resistance, except that
more TAU participants had at least 10 prior major depressive episodes,
and the VNS+TAU group had more electroconvulsive therapy before study
entry. Vagus nerve stimulation plus treatment as usual was associated
with greater improvement per month in IDS-SR30 than TAU across 12
months (p < .001). Response rates according to the 24-item
Hamilton Rating Scale for Depression (last observation carried forward)
at 12 months were 27% for VNS+TAU and 13% for TAU (p < .011).
Both groups received similar TAU (drugs and electroconvulsive therapy)
during follow-up.

Conclusions

This comparison of two similar but nonrandomized TRD groups showed that
VNS+TAU was associated with a greater antidepressant benefit over 12
months.

Note that there is an ongoing discussion in the journal about the
topic.  A subscription is required to view it, though.
 The bottom line is that some people are skeptical of the
study cited above, because it was not a randomized, double-blind study.
 The authors replied that there was indeed evidence that the
treatment helps.  They acknowledged the weaknesses of the
studies, but explained that the nature of the condition under study
necessitates the use of less-than-ideal study protocols.  They
also cited a href="http://www.journals.elsevierhealth.com/periodicals/bps/article/PIIS0006322305006190/abstract">second
study, also nonrandomized, that showed benefit.
 That study included a sham-treatment group as a control.
 



Unfortunately, the technical issues involved in interpreting these
studies are rather complex.  What is needed is a thorough,
balanced interpretation of the best available data.  It is not
helpful to have an article that focuses on the administrative and
political process of FDA approval, while tossing in some horror stories
of people with bad outcomes.  



It is a common journalistic practice to include some true-life detail
to add interest to a story.  But if the cases selected are
outliers, the article becomes unbalanced.  One of the most
fundamental lessons in evidenced-based medicine is that single case
reports are usually not helpful.  They do serve some purposes:
they can illustrate the range of possibilities, they can be useful as
teaching aids, and they can serve as a starting point for further
research.  But it is hazardous to try to draw any kind of
conclusion from them.