DTC fields incorrectly assigned DataType="datetime" and missing length

Re: DTC field DataType

Hi Karen,

Are there any particular reasons why you think --DTC variables should be text in Define.xml?

In our opinion, since the --DTC variables contain ISO 8601 formatted data, they should be assigned to datetime, date, or time data types available in Define.xml specification (section 2.1.2.4, page 14). The only ISO 8601 formatted variables that should be assigned the data type of text are durations like --DUR or --ELTM.

Thanks,
Max

DTC field DataType

Hi, Max. Yes, here's one reference: SDTM v3.1.2 Implementation Guide, p.37, second-to-last sentence on that page: "Implementation of the ISO 8601 standard means that date/time variables are character/text data types." Here's another in the same document: p.39, 2nd paragraph: "Using a character-based data type to implement the ISO 8601 date/time standard will ensure that the date/time information will be machine and human readable without the need for further manipulation, and will be platform and software independent." I've worked on several submissions for several major pharma companies, and they all have used text fields. Thanks again, Karen

DTC field DataType

You might want to take a look at the CRT-DDS specification, table 2.1.2.4 (Data Type Specifications).
Length is not defined in case the data type equals datetime, date or time.

SDTM only distinguishes between text and numeric variables (like SAS).
When you create a define.xml, you have to use the CRT-DDS spec, not the SDTM spec.

Lex Jansen

DTC field DataType

You are right, and after some searching it seems this problem was the focus of some vigorous debate last year, relating to differences between the CRT-DDS specification and HL7-XML. Apparently the latter treats dates as text fields. My immediate problem is that when my client tried to use an OpenCDISC-generated Define.xml file in WebSDM, it rejected it because of the DTC specification of datetime/null length, and used a default Define file. Changing the type/length to text/10 or text/16 worked. For what it's worth, note that the sample Define file that was posted with CDISC's draft Metadata appendix to SDTMIG v3.1.1 in 2007 uses a text datatype. Thanks again, Karen

Likely final answer is now in the draft SDTM MSG

Now that the draft SDTM Metadata Submission Guideline is available for public review on cdisc.org, you can find the likely final answer to this question in Table 3.3.2.1, pg 9, which confirms --*DTC should have an ODM data type of datetime, date, or time.