Background: This is a meta-analysis of randomized controlled trials (RCTs) of mindfulness-based interventions (MBIs) for a current episode of major depressive disorder.

Methods: Both English (PubMed, PsycINFO, Embase, and Cochrane Library databases) and Chinese (WanFang and CNKI) databases were systematically and independently searched. Standardized mean differences (SMDs) and risk ratio (RR) +/- their 95% confidence intervals (CIs) based on the random effects model were calculated.

Results: A total of 11 RCTs with 12 treatment arms (n = 764; MBIs = 363; and control group = 401) were identified and analyzed. Compared to the control group, MDD subjects receiving MBIs showed significant reduction in depressive symptoms (n = 722; SMD:-0.59, 95% CI:-1.01 to-0.17, I-2 = 85%, p = 0.006) at post-MBIs assessment, but the significance disappeared by the end of posttreatment follow-up. Subgroup analyses revealed that positive benefits of MBIs was associated with studies that had treatment as usual (TAU) control group, Chinese participants, open label design, no gender predominance, subjects younger than 44.4 years, and Jadad score >= 3, other illness phase and MBIs as augmentation group.

Conclusion: This meta-analysis found that MBIs was associated with reduction of depression severity immediately after MBIs but not at follow up endpoint. Further, the positive effects of MBIs were mainly driven by outlying studies. Higher quality of RCTs with larger samples and longer study duration are needed to confirm the findings.