Funnel plots of trials included in the meta-analysis for (A) systolic blood pressure and (B) diastolic blood pressure. The vertical line of Begg's funnel plot represents the pooled mean effect size, and the dotted lines represent the 95% confidence interval. P values are derived from Egger's test.
Ried et al. BMC Medicine 2010 8:39 doi:10.1186/1741-7015-8-39