[Health-related quality of life assessment in depression after low-frequency transcranial magnetic stimulation]

Major depressive disorder remains one of the leading causes of disability in developed countries despite pharmacological and psychological treatments. Patients with major depression have poorer health-related quality of life than persons of the general population, or patients with chronic somatic illness. Improvement of health-related quality of life in depression is thus a pertinent treatment objective. Both high-frequency repetitive transcranial magnetic stimulation (rTMS) over the left dorsolateral prefrontal cortex and low-frequency rTMS over the right dorsolateral prefrontal cortex have shown their effectiveness in medication-resistant depression. However, the Health-related Quality of Life questionnaire remains under-utilized to assess the effectiveness of rTMS in research or in a routine clinical setting. Our study aims to investigate in an open label trial the efficacy of low-frequency rTMS over the right dorsolateral prefrontal cortex on health-related quality of life and clinical outcomes in medication-resistant depression.

In a naturalistic trial, 33 unipolar and bipolar patients with medication-resistant depression were treated with daily low-frequency rTMS over the right dorsolateral prefrontal cortex for 4 weeks. Health-related quality of life was assessed using the SF-36 questionnaire. The SF-36 is a generic, self-administered, and worldwide-used questionnaire, consisting of 36 items describing eight health dimensions: physical functioning, social functioning, role-physical problems, role-emotional problems, mental health, vitality, bodily pain, and general health. Physical component summary and mental component summary scores were then obtained. Depression severity was assessed using the 21-item self-report Beck Depression Inventory. Anxiety severity was assessed using the State-Trait Anxiety Inventory. The SF-36, the Beck Depression Inventory and the State-Trait Anxiety Inventory were assessed before and after low-frequency rTMS. The effect of rTMS treatment on the SF-36 and the clinical outcome was evaluated for significance with the Wilcoxon two-tailed signed-rank test. The reliable change index (RCI) was calculated to determine clinically significant change in the eight dimension and composite scores of the SF-36 from pre-intervention to post-intervention, at the level of individual patients. Effect size (r) was then calculated, r values from 0.1 to 0.29, 0.3 to 0.49 and from 0.5 were considered as indicating small, medium and large effect sizes, respectively. Correlations between improvement in Health-related Quality of Life and improvement in the other rating scale scores were calculated using Spearman's correlation test.

There were significant improvements of 37.6% in the mental health (P=0.018), 130 % in the role-emotional problem (P=0.045), 15.5% in the physical functioning (P=0.008), 110.6% in the role-physical problem (P=0.002), 22.4% in the bodily pain (P=0.013) dimensions, 6.1% in the Physical Component Score (P=0.043), and 22,5 % in the Beck Depression Inventory (P=0.002). Eighteen patients (54%) showed clinically significant improvement in one of the two composite scores after RCI calculation. Seven out of the eight SF-36 dimension scores and the two composite scores showed effect sizes ranging from 0.12 to 0.38, indicating small to moderate effect. Significant correlations were found between improvement in the Beck Depression Inventory and improvement in the Mental Component Score, the social functioning, the mental health, the general health, the vitality and the physical functioning dimensions.

Small sample size and non-controlled design.

Low-frequency rTMS over the right dorsolateral prefrontal cortex improves Health-related Quality of Life in unipolar and bipolar patients with medication-resistant depression. Improvement in mental health-related quality of life is significantly correlated with improvement in depressive symptoms. However, further studies with larger samples and controlled designs are needed to clarify our findings.