Hi,

I have a dataset with information from two different registers. The registers contain the same type of observations (presence or absence of disease, coded as 0 or 1). My dataset contains 5 variable;
ID
date (for entry in register 1)
disease (in register 1)
date (for entry in register 2)
disease (in register 2).

I need to identify the first time study participants were coded as 1 (first time diagnosis) in either register 1 or 2. Anyone knows of a way to achieve this?

Best wishes,

David