Table 2:

Summary of analyses

VariableBase case estimatesEstimates, excluding Miyaoka et al.39Estimates, excluding studies deemed high risk of biasTrim and fill analysisTrim and fill analysis, excluding Miyaoka et al.39
Probiotic interventions
Participants with depression9 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 depression35 studies
Hedges’ g 0.31
(95% CI 0.15 to 0.46)
τ2 = 0.15
I2 = 74.4%
NA24 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 depression3 studies
Hedges’ g 0.39
(95% CI 0.04 to 0.73)
τ2 = 0.02
I2 = 26.6%
NA2 studies
Hedges’ g 0.41
(95% CI 0.17 to 0.65)
τ2 = 0.05
I2 = 42.9%
NANA
Participants without depression2 studies
Hedges’ g 0.78
(95% CI 0.19 to 1.37)
τ2 = 0.67
I2 = 89.9%
NANANANA
Synbiotic interventions
Participants without depression6 studies
Hedges’ g 0.68
(95% CI 0.36 to 1.00)
τ2 = 0.67
I2 = 89.9%
NA4 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.