Thanks to many helps from @Patrick_Ryan, @jswerdel, I've got the result from the Medicaid and Meicare for the comparison of combination treatment in hypertension study.
I'm trying to summarize this multi-national, multi-center result by using meta-analysis. I've never studied or used meta-analysis before.
So I have a question, which meta-analysis model should I use for this study: Fixed-effect vs. Random effect?
I thought many previous papers started with fixed-effect model and then moved to a random-effects model if the test for heterogeneity is significant.
The assumption for fixed-effect model is that all studies in the analysis share a common effect size. And the assumption of random-effect model is that there is a distribution of true effect sizes.
I have results from the representative population of whole Koreans, US Medicare and US medicare population. I prefer using 'random-effect model' because I don't believe there is a common effect size of hazard ratio among these population.
The characteristics and the outcome of Korean population would be differ from other countries. Generally, medicare population is much older than general population. Medicare population has its own characteristics, too.
I don't know which is the best way.
I think we need to develop best practice for meta-analysis in OHDSI
Is there anybody who can help me about this problem?