Paper 100

Have a Date with ISO? Using PROC FCMP to Convert Dates to ISO 8601

September 23, 2025: 8:30 AM - 9:00 AM

Foundational Coding Skills (FCS), Breakout Room #8

Authors	Abstract
Richann Watson	Programmers frequently have to deal with dates and date formats. At times, determining whether a date is in a day-month or month-day format can leave us confounded. Clinical Data Interchange Standards Consortium (CDISC) has implemented the use of the International Organization for Standardization (ISO) format, ISO® 8601, for datetimes in SDTM domains, to alleviate the confusion. However, converting “datetimes” from the raw data source to the ISO 8601 format is no picnic. While SAS® has many different functions and CALL subroutines, there is not a single magic function to take raw datetimes and convert them to ISO 8601. Fortunately, SAS allows us to create our own custom functions and subroutines. This paper illustrates the process of building a custom function with custom subroutines that takes raw datetimes in various states of completeness and converts them to the proper ISO 8601 format.

Richann Watson

Programmers frequently have to deal with dates and date formats. At times, determining whether a date is in a day-month or month-day format can leave us confounded. Clinical Data Interchange Standards Consortium (CDISC) has implemented the use of the International Organization for Standardization (ISO) format, ISO® 8601, for datetimes in SDTM domains, to alleviate the confusion. However, converting “datetimes” from the raw data source to the ISO 8601 format is no picnic. While SAS® has many different functions and CALL subroutines, there is not a single magic function to take raw datetimes and convert them to ISO 8601. Fortunately, SAS allows us to create our own custom functions and subroutines. This paper illustrates the process of building a custom function with custom subroutines that takes raw datetimes in various states of completeness and converts them to the proper ISO 8601 format.