OpenClinica User Manual/Standards

In general, standard names make it easy to reuse code (CRFs and rules) from project to project, and if you know the conventions, they make the projects easier to understand.

Standard variable names


Frequently used CRFs (Concomitant Medications, Adverse Events, Medical History etc.) in particular should use short, standard variable names (CDISC is a good source for example names).

CDISC has a set of standard variable names and fragments that should be used where possible. See CDASH ( and SDTM (, also see section 10.3.1 ‘Standardised and Reserved codes’ in the SDTM3.1.1ImplementationGuide.pdf ( All variable names should be prefixed with fragments that indicate the domain that the variable is from (e.g. VS is Vital Signs).

  1. Standard Code Lists - define and reuse standard codelists (RESPONSE_TYPE, RESPONSE_LABEL,RESPONSE_VALUES_OR_CALCULATIONS groups) to simplify the work of those extracting data.
  2. Standard Rule xmls - define standard rules for frequently used CRFs (e.g. use short codes for trials to avoid conflicts with other co-hosted trials, see Avoiding problems with OIDs).

If a repeating set of questions is developed as a separate CRF, the developer can just create and test that section as a CRF once. This is made easier if the developer has input into the development of the original CRF, and can try to standardise the look of repeating sections, which can be later developed as one OpenClinica CRF.

Defining Item_names to avoid problems when exporting to SAS and other formats (field lengths)


If a CRF's data will be exported for SAS, then the Item_names should be no more than 32 characters long to avoid import errors. For SAS programmers that will receive our data, shorter is better - because when writing code in SAS, there's no autocomplete.

When exporting to formats other than XML, avoid underscores in field and CRF names, as OpenClinica’s export inserts underscores to delimit CRFs and groups, and extra underscores make it difficult to automatically identify these delimiters and identify CRF, group and field names.