A meta-analysis on heart rate variability biofeedback and depressive symptoms

Figures

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  Figure 1. Flowchart illustrating study selection, review strategy and data extraction.

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  Figure 2. Risk of bias assessment. Low risk of bias is represented with green dots, high risk of bias in red, unclear risk of bias in yellow.

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  Figure 3. Forest plot, each square corresponds to one study and the lines represent 95% confidence interval. The size of each square represents the weight of the study. The diamond at the bottom represents the cumulative effect size with 95% confidence interval. Higher positive values indicate greater effect of the HRVB intervention compared with the control group.

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  Figure 4. Funnel plot. Black dots represent studies included in the present meta-analysis. The vertical line represents the effect size.

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  Figure 5. Plot illustrating the relationship between year of publication and cumulative effect sizes. In particular, the most recent the study, the greater the effect size. The area of the points is proportional to study variances. Three studies published in 2020 are not reported due to overlapping positions. Dashed lines indicate 95% CI, the dotted line indicate Hedges' g = 0 (i.e., no difference between groups).