Choosing the measure of effect size to extract&summarise in a meta-analysis

I am preparing a meta-analysis for a certain therapeutic intervention, and will be interested to quantify/summarise the change in various scores, pre-to-post intervention.

Which measure of effect size should I use, namely the effect size that I extract or compute from primary papers, and also that I later compute as a summary measure? I am not sure on which grounds to choose among the main choices:

• Cohen's d

• OR (the odds ratio)

• SMD (standardized mean difference)

Cohen's d is I guess most typically reported in papers so makes life a bit easier. On the other hand, some papers recommend ORs, although not over Cohen's d but over correlation coefficients.

Are some measures of effect sizes more suitable for some meta-analyses but not for others, e.g. those that look at the effect of an intervention (longitudinal) vs those that do a cross-sectional comparison?

• Use the one which is most clinically pertinent (typically the OR for a hard endpoint), unless it is reported by few studies. You can also pool all endpoints simultaneously with mvmeta in R or Stata, though. – Joe_74 Feb 7 at 11:04