Lucie L. Herrmann, MA; and Klaus P. Ebmeier, MD
Objective: So far no convincing answer
has emerged to the question of whether
transcranial magnetic stimulation (TMS) can make a
clinically useful contribution to the treatment of
depression. Here we examine whether multiple
sensitivity analyses can highlight parameters that predict
a favorable treatment response.
Data Sources: Medline, Embase, and
the Cochrane database for controlled trials were searched for relevant randomized controlled
trials using the expression (transcranial
magnetic stimulation or TMS) and
depression.
Study Selection: Thirty-three studies
were identified and included in the random-effects meta-analysis, and between 17 and 31
studies were included in the secondary analyses
comparing outcome of studies with different parameters.
Data Extraction: Study data were
extracted with a standardized data sheet. A
meta-analysis based on Cohen d effect size measure was
done for all studies and various subsets.
Regression analysis of effect sizes with study parameters
was done in 24 studies.
Data Synthesis: Active TMS treatment
was more effective than sham, but variability was
too great to take any single study design as
paradigmatic. No significant predictors of study
effect size were found. Mean effect sizes were
reduced, although still significant, in studies with
stimulation intensity below 90% of motor threshold
and new medication starting within 7 days before to
7 days after start of TMS.
Conclusions: The absence of significant
outcome predictors in the presence of significant variability of outcome measures can be
interpreted in 2 ways: either study sizes and
numbers and designs are insufficient to afford the
power necessary to detect such predictors or TMS has
a nonspecific effect on depression that is not
influenced by study parameters. Large-scale
comparative trials are necessary to decide between
these interpretations.
J Clin Psychiatry 2006;67(12):1870-1876
© Copyright 2006 Physicians Postgraduate Press, Inc.