This review assessed rapid-rate repetitive transcranial magnetic stimulation (rTMS) for major depression. The author concluded that the results suggest there is no difference between rTMS and sham treatment, but the studies may have been too small to detect a difference and further research is required. The review lacked a description of its methods but the author's conclusion reflects the limited included data.

To assess the efficacy of rapid-rate repetitive transcranial magnetic stimulation (rTMS) for the treatment of major depressive episodes.

MEDLINE, the Cochrane Controlled Trials Register and the meta Register of Controlled Trials were searched using the search terms reported. Reference lists in reviews were screened and abstracts from scientific meetings were scanned. The searches were conducted from 1966 to July 2003.

Study designs of evaluations included in the review

Parallel or crossover randomised controlled trials (RCTs) were eligible for inclusion if they reported adequate allocation concealment, blinding of the patients and investigators, and use of intention-to-treat analysis. Crossover studies had to report non significant carry-over effects or data from the first treatment period.

Specific interventions included in the review

Studies were eligible if they compared rapid rTMS with sham treatment applied with the coil angled between 45 and 90 degrees from the scalp. Rapid rTMS involved frequencies of 10 Hz or more, applied over the left dorsal prefrontal cortex (DLPFC) at an intensity of at least 80%, and was given over 5 to 10 days. Studies that used rTMS combined with starting a medication were excluded. The included studies used different frequencies, intensities, duration of train of pulses and days of treatment of rTMS.

Participants included in the review

Studies of adults with a major depressive episode diagnosed using the American Psychiatric Association's DSM-IV criteria were eligible for inclusion.

Outcomes assessed in the review

Studies that measured outcomes using the 21-item Hamilton Rating Scale for Depression and reported data suitable for inclusion in a meta-analysis (including post-treatment means with standard deviations) were eligible for inclusion.

How were decisions on the relevance of primary studies made?

The author did not state how the studies were selected for the review, or how many reviewers performed the selection.

Only RCTs that met the specified predefined validity criteria were included in the review (see Study Design of Evaluations Included in the Review). Validity was assessed as part of the inclusion criteria, but the author did not state who performed the validity assessment or how the process was conducted.

The author did not state how the data were extracted for the review, or how many reviewers performed the data extraction. For the three included crossover studies, data were only extracted for the first treatment period.

How were the studies combined?

Pooled weighted mean differences (WMDs) between treatments were calculated with 95% confidence intervals (CIs) using a random-effects model.

How were differences between studies investigated?

Statistical heterogeneity was assessed using the chi-squared statistic.

Six RCTs (91 participants) were included.

There was no evidence of heterogeneity between studies (P=0.33). There was no significant difference between rTMS and sham treatment (WMD -1.1, 95% CI: -4.5, 2.3, P=0.5).

The results suggest that there is no difference between rTMS and sham treatment for major depression, but there may have been insufficient data to detect a difference and further research is required.

The review addressed a clear question that was defined in terms of the participants, intervention, outcomes and study design. Several relevant sources were searched and attempts were made to minimise publication bias. It was not reported whether any language restrictions were applied. The methods used to select studies, assess validity and extract the data were not described, so it is not known whether any efforts were made to reduce reviewer errors and bias. Adequate information was given about the included studies. Studies were only included if they met specified strict inclusion criteria for quality. The strict inclusion criteria meant that the studies were clinically comparable. The studies were statistically homogeneous and combining them by meta-analysis was therefore appropriate. The author estimated the required sample size to detect a difference between treatments and correctly highlighted the low power of the included studies and the meta-analysis. The review was limited by the lack of a description of its methods, but the author's conclusions appear to reflect the limited included data.

Practice: The author did not state any implications for practice.

Research: The author stated that further adequately powered RCTs are required to compare precisely located DLPFC with well-described true sham control.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.