Review
Repetitive transcranial magnetic stimulation (rTMS) for obsessive–compulsive disorder (OCD): An exploratory meta-analysis of randomized and sham-controlled trials

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Abstract

Objective

Randomized and sham-controlled trials (RCTs) on repetitive transcranial magnetic stimulation (rTMS) for treating obsessive–compulsive disorder (OCD) have yielded conflicting results that may be due to limited statistical power among individual studies. We pursued the present systematic review and meta-analysis to assess the efficacy of rTMS for OCD and to generate hypotheses for more robustly powered RCTs.

Method

We searched the literature for RCTs on rTMS for OCD from 1995 through December 2012 using MEDLINE, EMBASE, PsycINFO, Cochrane Central Register of Controlled Trials, and SCOPUS. We then performed an exploratory random-effects meta-analysis with the main outcome measures as pre-post changes in Yale–Brown Obsessive Compulsive Scale (Y-BOCS) scores, response to treatment and overall dropout rates at study end.

Results

Data were obtained from 10 RCTs, totaling 282 subjects with OCD. The pooled Hedges' g for pre-post Y-BOCS scores was 0.59 (z = 2.73, p = 0.006), indicating a significant and medium-sized difference in outcome favoring active rTMS. Furthermore, response rates were 35% and 13% for patients receiving active and sham rTMS, respectively (OR = 3.4, p = 0.002). Sub-group analyses indicated that LF-rTMS and rTMS protocols targeting non-DLPFC regions (i.e., orbitofrontal cortex or supplementary motor area) seem to be the most promising for reducing OCD-related symptoms. No differences on baseline depression scores or dropout rates at study end were observed between active and sham rTMS groups, although OCD severity at baseline was higher in the active group.

Conclusions

Our exploratory analyses show that active rTMS seems to be efficacious for treating OCD. Moreover, LF-rTMS and protocols targeting the orbitofrontal cortex or the supplementary motor area seem to be the most promising. Nevertheless, future RCTs on rTMS for OCD should include larger sample sizes and be more homogeneous in terms of demographic/clinical variables as well as stimulation parameters and brain targets.

Section snippets

Search strategy

We identified articles for inclusion in this meta-analysis by:

  • Screening the bibliography of the previous general reviews on rTMS for OCD (Blom et al., 2011; Jaafari et al., 2012; Pigot et al., 2008), of the meta-analysis by Slotema et al. (2010), and of all included RCTs;

  • Searching MEDLINE, EMBASE, PsycINFO, the Cochrane Central Register of Controlled Trials (CENTRAL), and SCOPUS from January 1, 1995 until December 3, 2012;

The search procedures (including syntax, parameters, and results) are

Literature search

We retrieved 59 references (after discarding duplicates) from MEDLINE, PsycINFO, EMBASE, CENTRAL and SCOPUS. Of these, 10 met the eligibility criteria (Alonso et al., 2001; Badawy et al., 2010; Gomes et al., 2012; Kang et al., 2009; Mansur et al., 2011; Mantovani et al., 2010; Prasko et al., 2006; Ruffini et al., 2009; Sachdev et al., 2007; Sarkhel et al., 2010). Please refer to the Supplementary Material for a detailed description of the study selection procedure.

Included RCTs: main characteristics

Overall, 10 RCTs were included

Discussion

This is the first meta-analysis assessing the efficacy and acceptability of rTMS for OCD. Our findings show that active rTMS significantly reduced overall OCD-related anxiety and depressive symptomatology following a mean of 14 sessions. Furthermore, active and sham rTMS groups did not differ in terms of depression scores at baseline or dropout rates at study end, although baseline Y-BOCS scores for the active rTMS group were significantly higher. Thus, active rTMS efficacy for OCD might have

Conclusion

In contrast with rTMS trials for major depression, in which a small number of brain regions were investigated while demographic/clinical and/or stimulation parameters were manipulated (Daskalakis et al., 2008), the lack of such repeated studies for OCD and their overall heterogeneity limit our ability to conclusively synthesize the literature. We therefore cannot draw definitive conclusions about the clinical utility of rTMS for OCD. With this said, LF-rTMS (particularly targeting the SMA or

Role of the funding source

We received no funding for this study.

Contributors

None.

Conflicts of interest

Dr. Berlim has received a researcher-initiated grant from Brainsway Inc. Dr Van den Eynde and Mr Nicholas Neufeld report no potential conflicts of interest.

Acknowledgment

None.

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