Summary of analyses
| Variable | Base case estimates | Estimates, excluding Miyaoka et al. (39) | Estimates, excluding studies deemed high risk of bias | Trim and fill analysis | Trim and fill analysis, excluding Miyaoka et al. (39) |
|---|---|---|---|---|---|
| Probiotic interventions | |||||
| Participants with depression | 9 studies Hedges’ g 0.78 (95% CI 0.19 to 1.37) τ2 = 0.67 I2 = 89.9% | 8 studies Hedges’ g 0.41 (95% CI 0.17 to 0.65) τ2 = 0.05 I2 = 42.9% | 6 studies Hedges’ g 0.39 (95% CI 0.07 to 0.72) τ2 = 0.09 I2 = 57.0% | 9 studies; 0 missing Hedges’ g 0.39 (95% CI 0.19 to 1.37) τ2 = 0.67 I2 = 89.9% | 9 studies; 2 missing Hedges’ g 0.31 (95% CI 0.08 to 0.55) τ2 = 0.07 I2 = 50.4% |
| Participants without depression | 35 studies Hedges’ g 0.31 (95% CI 0.15 to 0.46) τ2 = 0.15 I2 = 74.4% | NA | 24 studies Hedges’ g 0.36 (95% CI 0.13 to 0.59) τ2 = 0.26 I2 = 81.4% | 35 studies; 0 missing Hedges’ g 0.31 (95% CI 0.15 to 0.46) τ2 = 0.15 I2 = 74.4% | NA |
| Prebiotic interventions | |||||
| Participants with depression | 3 studies Hedges’ g 0.39 (95% CI 0.04 to 0.73) τ2 = 0.02 I2 = 26.6% | NA | 2 studies Hedges’ g 0.41 (95% CI 0.17 to 0.65) τ2 = 0.05 I2 = 42.9% | NA | NA |
| Participants without depression | 2 studies Hedges’ g 0.78 (95% CI 0.19 to 1.37) τ2 = 0.67 I2 = 89.9% | NA | NA | NA | NA |
| Synbiotic interventions | |||||
| Participants without depression | 6 studies Hedges’ g 0.68 (95% CI 0.36 to 1.00) τ2 = 0.67 I2 = 89.9% | NA | 4 studies Hedges’ g 0.82 (95% CI 0.42 to 1.21) τ2 = 0.07 I2 = 41.7% | 6 studies; 1 missing Hedges’ g 0.77 (95% CI 0.43 to 1.11) τ2 = 0.11 I2 = 54.1% | NA |
Note: CI = confidence interval, NA = not applicable.