Analysing non-outcome variables in meta-analysis I am working on a meta-analysis project in suicidology. This is more like an academic exercise and will not necessarily be submitted for publication, but I try to be as rigorous as possible.
Now here is my question: am I allowed to analyse data that has not been considered as an outcome (primary or secondary) in the original publications? To be more precise, the studies I plan to include in the meta-analysis generally had outcomes like suicidal behaviour or suicidal ideation. I'd like to analyse deaths by suicide instead. Most of the articles mention the number of deaths by suicide in each study group, sometimes in the discussion section, but it was never considered as an outcome. Is it legit to extract these numbers and perform an analysis on them?
Thank you very much in advance!

You are perfectly in order to analyse any outcome reported in the studies. It does not matter if it was the original point of the study.
Having said that there is one thing to beware of. If the outcome was really quite an incidental one it may be that the only studies which reported it were the ones which found a specific result and your meta-analysis would hence by biased. In the case of studies on suicide it seems unlikely that this would have happened with death as an outcome.
