Hello everyone, it is good to be here asking some useful help or advice. I am now trying to run an instrumental variable analysis in a survival analysis-based research. My topic lies in pharmacoepidemiology field, and the outcome is event of interest, which is not death though. I have used PROC PHREG twice to mimic 2SLS (two stage least squares, like PROC REG twice in traditional linear regression). However, it came out extremely weird results (e.g., hazard ratio showing 1x10^8...). It is obviously wrong. If there is any possible or practical advice to deal with this situation? Thanks for your reading and wishing for any suggestions!
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