Meta-analysis - between group difference p-values

Hi,

I am performing a meta-analysis looking at the incidence of a specific complication (per 1,000) across three non-overlapping groups of exposures.

The metan command in stata provides the pooled mean and confidence intervals for each of the three groups. Can someone please tell me how I compare if the three groups are statistically different and calculate p-values? I could do this with meta-regression but that is an insensitive method I think.

Thanks,

Ashwin