APVS - Unit Standardization

g Gopal

on July 24, 2023

Hi,

The information about Associated person captured as "Weight in (grams) at Birth". Please suggest, do we need to standardize the results in APxx domains as like we are doing in SDTM findings domains.

Do we need to convert gram to Kilogram in APVS.VSSTRESC variable for the Weight assessment?

Thanks in Advance.

Forums: SDTM

j Jozef

on July 25, 2023

APVS - Unit Standardization

No!

The idea behind --STRESC/--STRESN/--STRESU is that when one has different units for the results of the same tests in --ORRES (and thus the reviewer will have it hard to compare the results between different subjects), one standardizes all results for that test into a single unit.
For example, if for some newborns, the weight was measured in grams, and for others in pounds, then you would "standardize" to a single unit (whatever that unit is, that is your choice). If all measurements for a test were done in the same unit, there is no need to "standardize", and one can just copy from --ORRES/--ORRESU.

P.S. This question has little to do with P21, a much better forum for such questions is the "LinkedIn CDISC - SDTM Experts" forum: https://www.linkedin.com/groups/2758697/ ("only" 3276 experts there...)

Sergiy

on July 25, 2023

P21

Hi Gopal, I'd say that it…

Hi Gopal,

I'd say that it would be safe to use the same VSSTRESU for the same tests across VS and APVS domains ("kg"?) and then convert back to analysis-specific units ("grams") in ADaM dataset if needed.

Also, additional details about study protocol could be helpful. For example, "Weight in (grams) at Birth" may represent historical data rather than assessments of Vital Signs during the study. If you observe weight of grown subjects during the study and use "Weight in (grams) at Birth" as some kind of reference data, I may even keep those in Subject Characteristics domain instead of Vital Sign.

Kind Regards,
Sergiy