Between group comparisons in meta-analysis?

Hi,

I am using metaprop to compare the pooled proportions of a particular outcome across different groups. I get the following output:

Group 1

Sub-total |
Fixed pooled ES | 0.13 0.13 0.13 53.73

Group 2

Sub-total |
Fixed pooled ES | 0.04 0.03 0.04 41.55


Group 3

Sub-total |
Fixed pooled ES | 0.42 0.39 0.45 0.12


I’m not sure how to now statistically compare these subgroups. At the bottom, I get this statistic:

Significance test(s) of ES=0


I don’t know if it is possible to change the effect size reference from 0 to 0.13 (using Group 1 as the reference standard)?

Thanks,

Ashwin