Mindfulness on Rumination in Patients with Depressive Disorder: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Objective: To systematically evaluate the effectiveness of mindfulness-based interventions (MBIs) on rumination among patients with depression and their efficacy across countries and year of publication and control conditions. Methods: Web of Science Core Collection, Medline, BIOSIS Citation Index, KCI-Korean Journal Database, SciELO Citation Index, PubMed, Cochrane Library, and Embase were searched to include randomized controlled trials of MBIs for depressive rumination that met the criteria. The Rumination Scale was used as the primary outcome indicator; Depression, mindfulness, and anxiety indexes were selected as the secondary outcome indicators. An evaluation of bias risk was conducted to identify possible sources of bias based on methodological and clinical factors. RevMan5.3 software was used to perform a meta-analysis of the extracted data. Results: Nineteen studies with 1138 patients were included. Meta-analysis showed that MBIs could significantly reduce rumination levels in patients with depression (standardized mean difference (SMD) = −0.46; 95% confidence interval (CI): −0.58, −0.34; p < 0.001), notably improve depression (SMD = −0.58; 95% CI: −0.83, −0.32; p < 0.001), enhance mindfulness ability (SMD = 0.95; 95% CI: 0.57, 1.32; p < 0.001), and reduce the anxiety of patients with depression (SMD = −0.45, 95% CI: −0.62, −0.27; p < 0.001). MBIs conducted in Asia improved rumination better than studies in Europe and North America (SMD = −2.05 95% CI: −4.08, −0.01; p < 0.001) but had no greater effect than behavior activation on depression. The interventions carried out in the past 5 years were significantly better than earlier studies in improving mindfulness levels (SMD = 2.74; 95% CI: 0.81, 4.66; p = 0.005). Conclusions: MBIs are effective in the treatment of depression as they produce pleasant improvement in rumination and depression, decrease the degree of anxiety, and enhance mindfulness levels compared to controls. In newer forms of MBIs, regional differences need to be considered when designing the intervention program. More large, high-quality randomized controlled studies are needed to confirm the conclusion that the effectiveness of MBIs has differences in terms of the trial area and year of publication.