Paper 7

Worried about that Second Date with ISO? Using PROC FCMP to Convert and Impute ISO 8601 Dates to Numeric Dates

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

Foundational Coding Skills (FCS), Breakout Room #8

Authors	Abstract
Richann Watson	Within the life sciences, programmers frequently have to deal with dates in order to determine durations and number of days from a reference point. Within Study Data Tabulation Model (SDTM) domains, Clinical Data Interchange Standards Consortium (CDISC) has implemented the use of the International Organization for Standardization (ISO) format, ISO® 8601, for datetimes. While this helps to standardize how dates and times are captured so that there is no confusion as to what the date represents, it does not help from an analysis perspective. Within SDTM, these ISO dates are character dates and sometimes have missing components. From an analysis purposes the dates need to be converted to a numeric date and sometimes imputation of partial dates is needed. There are formats that can convert a complete ISO date to numeric date, but what if the date is a partial date. While SAS® has myriad functions, there is no function that will help with this conversion and imputation. Fortunately, with the use of the FCMP procedure, we are able to create our own custom functions to help achieve our desired goal. This paper illustrates the process of building a custom function that will take a date that is captured in the appropriate ISO format in SDTM (--DTC) and convert it to numeric date while also imputing any missing components. In addition, it will set the corresponding date imputation variable (--DTF) to the correct level.

Richann Watson

Within the life sciences, programmers frequently have to deal with dates in order to determine durations and number of days from a reference point. Within Study Data Tabulation Model (SDTM) domains, Clinical Data Interchange Standards Consortium (CDISC) has implemented the use of the International Organization for Standardization (ISO) format, ISO® 8601, for datetimes. While this helps to standardize how dates and times are captured so that there is no confusion as to what the date represents, it does not help from an analysis perspective. Within SDTM, these ISO dates are character dates and sometimes have missing components. From an analysis purposes the dates need to be converted to a numeric date and sometimes imputation of partial dates is needed. There are formats that can convert a complete ISO date to numeric date, but what if the date is a partial date. While SAS® has myriad functions, there is no function that will help with this conversion and imputation. Fortunately, with the use of the FCMP procedure, we are able to create our own custom functions to help achieve our desired goal. This paper illustrates the process of building a custom function that will take a date that is captured in the appropriate ISO format in SDTM (--DTC) and convert it to numeric date while also imputing any missing components. In addition, it will set the corresponding date imputation variable (--DTF) to the correct level.