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Friday, August 05, 2005

Implanted Brain Stimulators for Depression

http://www.usatoday.com/news/health/2005-07-17-brain-depression_x.htm

Stimulating the brain via some external electrical device for the treatment of depression has been advocated (at least commercially) since the mid-80's. No device has yet been FDA approved.

The Cyberonics device mentioned in the USA today article is IMPLANTED in your brain. Ick. You should have some serious, intractible, suicidal depression before ever considering such a thing. But, it does have FDA approval.

Remember, FDA CDRH approvals, even PMA approvals, are more concerned with safety, and demonstration that the device conforms to its labeling, rather than much determination as to whether or not it actually achieves a therapeutic purpose. Apparently, following initial FDA approval last year, CDRH asked the manufacturer for additional statistical analysis within their clinical study. This has been submitted and in July 2005, the FDA updated the labeling and summary of Safety and Effectiveness documents.

Here's what the FDA looked at in it's approval:



The overall FDA summary is positive in the device's ability to effect outcomes in the labeled populations. Labeling is one key here, the indicated population truly is sincerely desparate.

Other keys. The FDA looked at only one, on-going study, sponsored by the manufacturer. A manufacturer who is trying to woo investors, see a return on research investment, and otherwise has every stake in the product's success. The design and presentation of the study to the FDA left much to be desired. It wasn't a very ideal study. The conclusions of the CDRH analysis of the additional requested study-related data about the active (D-04) and control (D-02) groups reads, in part:

"Due to above statistical issues, such as questionable concordance between HRSD- 24 and IDS-SR, questionable pooling of multi-center data for comparison of proportions of responses, statistically insignificant findings from censored and overlapping sites (Tables 8-C and 8-D) for IDS-SR primary effectiveness endpoint (Slope) and HRSD-24 secondary effectiveness endpoint (Response proportions), it is unclear whether the effectiveness claim of D-02 over D-04 group patients has been demonstrated."

My summary, if you go by what the manufacturer says, the implanted brain stimulator can likely help out depression when all other things fail. If you go by a literal analysis of the technology, it realy hasn't been demonstrated that we can predict better outcomes for depression by using implanted brain stimulation, than by not using one. Implanting brain stimulators is risky, and a clear benefit has not been demonstrated practically enough to offset the risks and expense.

It's depressing to think there will probably be plenty of people who will want one, for all kinds of reasons, and enough willing surgeons around to meet the demand. -dras

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