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FDAB036: Study Day must not be negative in EX
there is no *DY=0 in SDTM data.
Hi!
SD1135 checks for data entry errors in study drug dosing dates.
RFSTDTC is usually based on either date of Randomization or the first study drug dose. Therefore, calculated study days for drug administration are expected to be positive integer values. Note that there may be some exceptions based on particular study designs.
A "Day 0" term in your study Protocol is outdated and not recommended by FDA, because it introduces confusions.
Most likely in your study SDTM data "Day 0" will be *DY=1 and all "Day X" will be *DY=X+1, if X>=0.
Definition of study days is based on RFSTDTC:
- If date is before RFSTDTC day, then *DY=(RFSTDTC - *DTC)
- If observation date is on the same day as RFSTDTC or later, then *DY=(*DTC-RFSTDTC)+1
You have flexibility to define RFSTDTC. However, calculation of Study Days (*DY) variables must follow SDTM specs above.
As you can see there is no *DY=0 in SDTM data.
Regards,
Sergiy
I am confused about business rule FDAB036 which says "Study Day must not be negative" for EX. This rule is different from the SDTM IG rule which is Study Day must be >=0. I have been given a study where the protocol and SAP definition of Study Day is date of first dose is Day 0. The SDTM datasets used the SAP definition of Study Day instead of the SDTM IG definition of Study Day. Day 0 in the EX dataset meets the requirement for the business rule because all the study days in EX are >=0. Is it acceptable to use a different definition of study day in SDTM so long as it meets this business rule? Thank you for your input.