[R-meta] Correlation between two continuous outcome

[Ishtiaq Ahmed]

Hi everyone,
I hope everyone is doing well. My understanding of correlation meta-analysis is limited, and I'm seeking to enhance it. Currently, I'm conducting a meta-analysis to assess the effect of X intervention on both pain intensity and several pain biomarkers (such as BDNF, beta-endorphin, etc.) as compared with the control. I'm particularly interested in exploring the correlation between pain intensity and BDNF levels, both of which are continuous variables.
I used escalc() to calculate the standardized mean difference (SMD) for pain intensity, considering the varying measurement scales between the intervention and control groups. Additionally, I've also calculated the mean difference (MD) for BDNF levels using the differences between the intervention and control groups.
My question is whether it's possible to convert SMD/MD to correlation coefficient (r) to perform the correlation meta-analysis. Alternatively, are there other approaches to utilizing SMD and MD for this analysis? Additionally, some of the studies (though not all) have provided beta-values for the correlation between pain intensity and BDNF. Can I incorporate these beta-values into the meta-analysis?

I would greatly appreciate any suggestions or sources you can provide.



Best regards,


Ishtiaq Ahmed



Ph.D. Researcher

Vrije Universiteit Brussels


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