Date to numeric conversion in datashield

Let’s imagine a clinic keeping track of their patients’ DoB and first visits.

Birth Visit
1959-11-22 2021-06-12
1961-01-07 2021-06-25
1992-06-19 2018-12-26

In DataSHIELD, we would like to pool ages of diagnoses, based on dates of birth and visit, like so:

Birth Visit Age of Diagnosis
1959-11-22 2021-06-12 61
1961-01-07 2021-06-25 60
1992-06-19 2018-12-26 26

I am fairly certain this should be possible through assignment operations but I was not able to find how to do this. Do I have no choice but to compute AoD locally, before creating the table on DataSHIELD?

Thanks in advance!

Hi Ahmet,

The dsSwissKnifeClient package has some functions to deal will dates (see for example dssAddDaysInterval). However, i have never use this package so i can’t give any further information.


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Hi Ahmet,

ISGlobal has produced a package called dsDates (GitHub: isglobal-brge/dsDates), but I don’t know if it is still supported.


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dssAddDaysInterval in conjunction with dssDeriveColumn did the trick!


# Compute Age in Days
  description.list= list(
    'age_in_days' = list( end_date='Visit',start_date ='Birth')
  datasources= conns)

# Compute Age in Years

dsSwissKnifeClient::dssDeriveColumn('D_', 'age_in_years', 'age_in_days/365', datasources = conns)