Ten randomised controlled trials (RCTs) were included in the review (n=232 participants). This included six parallel-arm double-blind placebo-controlled randomised trials and four cross-over RCTs. Results of quality assessment were not presented in full.
Overall, the effect of treatment with repetitive transcranial magnetic stimulation on auditory hallucinations in patients with schizophrenia was 0.514 (95% CI 0.225 to 0.804). No statistical heterogeneity was found. File drawer analysis suggested that 38 additional studies, showing no benefit from repetitive transcranial magnetic stimulation treatment, would be needed to reverse these findings.
Fixed-effect meta-regression analyses of the effect size as a function of total number of stimulations, repetitive transcranial magnetic stimulation intensity and duration of treatment were not statistically significant. Further analyses revealed a significant time x treatment interaction (F=7.55, df=1.31, p<0.01), which showed that over time there was a significant change in auditory hallucination scores for patients with schizophrenia treated with repetitive transcranial magnetic stimulation.