Output issue, NAs

[Antros89]

Hi and thank you for an amazing package. I am running into a recurrent issue when running the package and i cannot debug it.

I am employing two datasets to examine all comorbidities prior to admission, utilizing the parameter days = c(-Inf, 0). When the current admission is the first instance(there are no earlier ICD codes documented prior to the current admission), the output in the comorbidities is NA, whereas my expectation is that it should return FALSE.

Could you possibly provide some insights or suggestions on how I might address this issue? Any assistance would be greatly appreciated!