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Timing Variables: Collection, Conversion, and Imputation of Dates - CDASH Model 1.2 and Implementation Guide 2.2 - Wiki (cdisc.org)

Collection of Dates

Collect dates in such a way as to allow sites to record only the precision they know. The system should also store only the collected precision. Any incomplete dates must remain incomplete with no imputation and no “zero-filling” of missing components.

Data collection and database processes should allow for the possibility of partial dates and times, because a partial date may be the most precise information that can be collected for some data. (For an example of when it may be necessary or appropriate to collect partial dates, see Section 7.3, DM - Demographics.) In some countries, collection of a complete date of birth is restricted under privacy rules, so only a year (or year and month) of birth might be collected. Other examples of commonly collected partial dates occur in the Concomitant Medications (CM) and Medical History (MH) domains, where subjects might not remember the complete date of when they started to take a medication or when a significant medical history condition began.

If a full date is collected (or expected), the CDASH variable --DAT or all 3 date components (i.e., --DATYY, --DATMO, --DATDD) should be included on the collection tool. If a partial date can be collected in a single field, the CDASH --DAT should be used. If a partial date must be collected as separate database fields to collect year, month, and day, refer to the CDASH Model for examples of standard naming fragments (--YY, --MO, --DD, --TIM). The capabilities of individual software systems (e.g., EDC) will determine which variable names are needed. CDASH uses separate data collection fields for dates and times. If times are collected, it is expected that these will be used with the appropriate collected date to derive the related SDTM date variable in ISO 8601 format.

The following guidance...

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