The FDA approval of this device has been controversial (2). The initial study submitted to the FDA was rejected. The folks at Neurostar (the manufacturers of the device) did a post-hoc analysis of that data. They discovered that patients, who failed to respond to only 1 antidepressant, subsequently responded to rTMS greater than sham (27.3% versus 10.5%). Based on this analysis, the FDA approved rTMS for the treatment of MDD in patients who have failed only 1 antidepressant trial.
In this month's Archives of General Psychiatry, is an article titled "Daily Left Prefrontal Transcranial Magnetic Stimulation Therapy for Major Depressive Disorder" (3). This study was funded by the NIMH and is the first nonindustry funded multisite study of rTMS (though some of the researchers are paid consultants of the TMS manufacturer). It involved 190 people.
What supposedly separates this study from all others, is the sham treatment. One major criticism of the previous TMS research is that the sham treatment was not convincing enough to prevent unblinding (for example, sham did not cause scalp irritation or facial twitching). The researchers went to great lengths to develop a sham treatment which produced the similar physical sensations of rTMS to prevent unblinding.
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Unfortunately, approximately 50% of the active treatment group correctly guessed which treatment condition they were in. A full 66% of placebo participants correctly guessed their condition. In truth, the level of unblinding is not a whole lot different from standard antidepressant drug trials (since placebos are inactive). The patients, on average, were similar to the patients in the Neurostar post-hoc analysis. The participants failed 1.51 antidepressant trials.
The primary outcome was remission, defined as a score of 3 or less on the HAM-D or 2 consecutive HAM-D scores less than 10 during phase 1 of the study. Phase 1 was three weeks in duration. Patients received rTMS once a day for 50 minutes (5 days a week).
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Similar to the Neurostar analysis, those who did remit were less treatment resistance (i.e., failed only 1 antidepressant trial). The number needed to treat (NNT) was 12. That means, 12 people will need to be treated with rTMS before another person, who otherwise would have not remitted without intervention, finally does remit. That's not very good. However, that number is not far off from standard antidepressant drug trials.
Does rTMS have any practical value as a future treatment for depression? Based on these results, one will need to attend a 50 minutes session everyday (excluding weekends) for 3-5 weeks to see some sort of result. That is in stark contrast to attending psychotherapy 1-2 times a week or visiting a psychiatrist once every 4-6 weeks. As Daniel Carlat points out in his monthly report (1), each treatment session would cost approximately $400. Insurance companies do not currently cover this treatment (and probably never will). Moreover, the group of patients who did remit (i.e., those who failed only 1 antidepressant trial) is not very marketable. Odds are they will try a second antidepressant instead. According to the Star-D results, the odds of improvement are 30% on a second antidepressant compared to 14% of rTMS. Presently, rTMS just does not make economic sense.
George MS, Lisanby SH, Avery D, McDonald WM, Durkalski V, Pavlicova M, Anderson B, Nahas Z, Bulow P, Zarkowski P, Holtzheimer PE 3rd, Schwartz T, & Sackeim HA (2010). Daily left prefrontal transcranial magnetic stimulation therapy for major depressive disorder: a sham-controlled randomized trial. Archives of general psychiatry, 67 (5), 507-16 PMID: 20439832