Timing variables defined in the CDASH Model and implemented per the TIG are used to collect when observations occur, and periods of time associated with observations. The following table describes how fields will be used to collect the timing of observations.


NumCollection Variable UseImplementation
1By observation class
  • In Events and Interventions domains, timing variables will generally be used to collect the start date of the event or intervention.
  • In Findings domains, timing variables will generally be used to collect the date associated with test results; except in cases where results are generated from the testing of specimens (e.g., laboratory testing). In such cases, timing variables will be used to collect the date of the specimen collection for the associated test.
2

Collection of visits 

  • Protocols define visits to describe the timing of assessments and procedures.
  • Variables VISIT and VISITNUM will generally be used to collect visits associated with observations.
  • Variable VISDAT will generally be used to collect the date visits occurred. 
3Precision of dates
  • Dates will be collected in a way that allows individuals involved in data collection to record only the precision they know.
    • Data collection and database processes will allow for the possibility of partial dates and times, because a partial date may be the most precise information that can be collected.
    • The system will also store only the collected precision. Incomplete dates will remain incomplete in the system with no imputation and no “zero-filling” of missing components.
  • If a full date is expected or collected, variable --DAT or all 3 date components (i.e., --DATYY, --DATMO, --DATDD) will be included on the CRF.
  • If a partial date can be collected in a single field, variable --DAT will be used.
  • If a partial date must be collected in separate fields for 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 fragments will be used.
4Imputation of dates
  • The collected value of variable VISDAT can be applied to all observations for a given visit as appropriate, or timing variables can be included for specific observations in the body of the CRF.
  • Missing parts of the date will not be imputed by the system.
5

Variable DTHDAT 

  • The CDASH Model defines DTHDAT as a timing variable, as it may be collected via any CRF deemed appropriate by the applicant. The date of death should only be collected once for a subject.

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