[R-meta] meta-regression for incidence rate

[Giorgio Maria Agazzi]

Dear all,
I am planning to do a meta-regression with the intent to compare trial
patient characteristics to the incidence of an outcome in the time period
between t=0 and t=2 years. Every study reports the number at risk at t=0
and t=2 years and the kaplan-meier curve, so I'm able to digitize the curve
and extract the percentages of events.
I was thinking of doing a meta-regression and using as effect size the
freeman-tukey transformed incidence rate. I'm not sure this is the best way
and I have also another question, how can I calculate the total number at
risk as requested by metafor? for the number of events I can calculate it
by digitizing the plot and calculating the percentage of people that had
the outcome.

Thank you very much!

gma

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