# SDTM question for EPOCH variable **URL:** \ **Category:** SDTM\ **Created:** [October 23, 2013, 3:06pm UTC](https://forum.certara.com/t/sdtm-question-for-epoch-variable/543 "2013-10-23T15:06:08Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![mdigian](https://avatars.discourse-cdn.com/v4/letter/m/85e7bf/32.png) [@mdigian](https://forum.certara.com/u/mdigian)\ **Post date:** [October 23, 2013, 4:12pm UTC](https://forum.certara.com/t/sdtm-question-for-epoch-variable/543/1 "2013-10-23T16:12:17Z")
Epoch is a permissible variable in CDISC, but it’s also a variable requested by FDA in CDER Common Data Issues document and should be included in the dataset for these domains: | Events | AE | | --- | --- | | Events | CE | | Events | DS | | Events | DV | | Events | EVENTS | | Events | MH | | Findings | DA | | Findings | EG | | Findings | FA | | Findings | FINDINGS | | Findings | LB | | Findings | MS | | Findings | PC | | Findings | PE | | Findings | PP | | Findings | QS | | Findings | RS | | Findings | TR | | Findings | TU | | Findings | VS | | Interventions | CM | | Interventions | EX | | Interventions | INTERVENTIONS | | Interventions | SU | ---
**Author:** ![biess\_330](https://avatars.discourse-cdn.com/v4/letter/b/ecae2f/32.png) [@biess\_330](https://forum.certara.com/u/biess_330)\ **Post date:** [October 24, 2013, 3:33pm UTC](https://forum.certara.com/t/sdtm-question-for-epoch-variable/543/2 "2013-10-24T15:33:54Z")
Thank you @mdigian for your response! ---
**Author:** ![XML4Pharma](https://avatars.discourse-cdn.com/v4/letter/x/b2d939/32.png) [@XML4Pharma](https://forum.certara.com/u/XML4Pharma)\ **Post date:** [January 6, 2014, 10:29am UTC](https://forum.certara.com/t/sdtm-question-for-epoch-variable/543/3 "2014-01-06T10:29:13Z")
This is an example of the very bad practice that a stakeholder is changing the standard after its publication, where it had the opportunity to request for the incorporation of the variable during the review period. How can we trust standards when a stakeholder deviates from it and creates its own “dialect”? ---
**Author:** ![rosie](https://avatars.discourse-cdn.com/v4/letter/r/5daacb/32.png) [@rosie](https://forum.certara.com/u/rosie)\ **Post date:** [February 25, 2014, 2:41pm UTC](https://forum.certara.com/t/sdtm-question-for-epoch-variable/543/4 "2014-02-25T14:41:41Z")
Thanks, helpful answer, and something that’s not easy to discover from the FDA website! Downloaded OpenCDISC just a couple of days ago and already it’s proving very helpful! ---
**Author:** ![mdigian](https://avatars.discourse-cdn.com/v4/letter/m/85e7bf/32.png) [@mdigian](https://forum.certara.com/u/mdigian)\ **Post date:** [February 25, 2014, 3:44pm UTC](https://forum.certara.com/t/sdtm-question-for-epoch-variable/543/5 "2014-02-25T15:44:58Z")
This was published in December 2011 by the FDA, a major stakeholder of the standards. [http://www.fda.gov/downloads/Drugs/DevelopmentApprovalProcess/FormsSubmissionRequirements/ElectronicSubmissions/UCM254113.pdf](http://www.fda.gov/downloads/Drugs/DevelopmentApprovalProcess/FormsSubmissionRequirements/ElectronicSubmissions/UCM254113.pdf) SDTM 3.1.3 was published after this guidance. Do you know if CDISC simply chose not to change EPOCH’s core value from **Perm** to **Req** for certain domains ? ---
**Author:** ![rosie](https://avatars.discourse-cdn.com/v4/letter/r/5daacb/32.png) [@rosie](https://forum.certara.com/u/rosie)\ **Post date:** [October 7, 2014, 11:20am UTC](https://forum.certara.com/t/sdtm-question-for-epoch-variable/543/6 "2014-10-07T11:20:10Z")
Hi, Anyone know where the EPOCH variable should go in the table? At the end? After all the --DTC/–DY variables? Anywhere? Thanks, Rosie ---
**Author:** ![Sergiy](https://sea1.discourse-cdn.com/certara/user_avatar/forum.certara.com/sergiy/32/2553_2.png) [@Sergiy](https://forum.certara.com/u/Sergiy)\ **Post date:** [October 13, 2014, 7:19pm UTC](https://forum.certara.com/t/sdtm-question-for-epoch-variable/543/7 "2014-10-13T19:19:37Z")
Hi Rosie, A position of any variable including EPOCH is defined by SDTM Model. E.g., for SDTM v1.4 see a Table 2.2.5 (Timing VAriables for All Classes) on page 19: VISITNUM VISIT VISITDY TAETORD **EPOCH** –DTC –STDTC –ENDTC –DY … EPOCH should be just before --DTC, --STDTC variables. Kind Regards, Sergiy ---
**Author:** ![rosie](https://avatars.discourse-cdn.com/v4/letter/r/5daacb/32.png) [@rosie](https://forum.certara.com/u/rosie)\ **Post date:** [October 14, 2014, 7:45am UTC](https://forum.certara.com/t/sdtm-question-for-epoch-variable/543/8 "2014-10-14T07:45:10Z")
Thanks, Sergiy! I was using the SDTM IG and forgot about the SDTM doc. Really don’t understand why they publish them as separate docs… ---
**Author:** ![jing.liu](https://avatars.discourse-cdn.com/v4/letter/j/a4c791/32.png) [@jing.liu](https://forum.certara.com/u/jing.liu)\ **Post date:** [December 17, 2015, 2:41am UTC](https://forum.certara.com/t/sdtm-question-for-epoch-variable/543/9 "2015-12-17T02:41:35Z")
Hi @mdigian , I don’t understand why MH also need an EPOCH variable? All MH records are supposed to be collected during screening phase. ---
**Author:** ![mdigian](https://avatars.discourse-cdn.com/v4/letter/m/85e7bf/32.png) [@mdigian](https://forum.certara.com/u/mdigian)\ **Post date:** [December 17, 2015, 3:14am UTC](https://forum.certara.com/t/sdtm-question-for-epoch-variable/543/10 "2015-12-17T03:14:00Z")
Think of the SDTM 1.x as the generic model for the 3 general observation classes: FINDINGS, INTERVENTIONS, EVENTS. It defines the blue print and superset of variables available for those classes. The order of variables is a general starting point. The IG then inherits and implements a generic class as a domain while supplying domain specific semantics (controlled terminology assignments, assumptions, prohibiting use of some variables). In some cases, the domain will override the variable order. in the case where a variable is not mentioned and not prohibted, its order is inherited from the parent class. This is why they publish two separate docs. Base Parent (Model) and IG (instance of model). SDTM 1.x is implemented by the following: 1. SDTM-IG 3.x (clinical/human) 2. SEND-IG 3.x (non-clinical/toxicology/animal) 3. AP-IG 1.0 (Associated Persons) 4. MD-IG 1.0 (Medical Devices) 5. PGx-IG 1.0 (Pharmacogenomics/genetics) 6. TA-UGs (currently over 20 Therapeutic Area User Guides) ---
**Author:** ![jing.liu](https://avatars.discourse-cdn.com/v4/letter/j/a4c791/32.png) [@jing.liu](https://forum.certara.com/u/jing.liu)\ **Post date:** [December 17, 2015, 5:23am UTC](https://forum.certara.com/t/sdtm-question-for-epoch-variable/543/11 "2015-12-17T05:23:39Z")
Hi [mdigian](http://www.opencdisc.org/users/mdigian), I don’t understand why MH also need an EPOCH variable? All MH records are supposed to be collected during screening phase. Thanks! ---
**Author:** ![jing.liu](https://avatars.discourse-cdn.com/v4/letter/j/a4c791/32.png) [@jing.liu](https://forum.certara.com/u/jing.liu)\ **Post date:** [December 17, 2015, 5:23am UTC](https://forum.certara.com/t/sdtm-question-for-epoch-variable/543/12 "2015-12-17T05:23:46Z")
Hi [mdigian](http://www.opencdisc.org/users/mdigian), I don’t understand why MH also need an EPOCH variable? All MH records are supposed to be collected during screening phase. Thanks! ---
**Author:** ![mdigian](https://avatars.discourse-cdn.com/v4/letter/m/85e7bf/32.png) [@mdigian](https://forum.certara.com/u/mdigian)\ **Post date:** [December 17, 2015, 3:45pm UTC](https://forum.certara.com/t/sdtm-question-for-epoch-variable/543/13 "2015-12-17T15:45:00Z")
_ **Short answer** _, FDA requires it in their Tech Conformance Guide: [http://www.fda.gov/downloads/ForIndustry/DataStandards/StudyDataStandards/UCM384744.pdf](http://www.fda.gov/downloads/ForIndustry/DataStandards/StudyDataStandards/UCM384744.pdf) _“..variable EPOCH should be included for every clinical subject-level observation … This will allow the reviewer to easily determine during which phase of the trial the observation occurred as well as actual intervention the subject experienced during that phase”_ **My take / long answer…** while MH is “supposed” to be collected during screening phase, perhaps a use case will develop where it is collected throughout the study. Perhaps for early stage alzheimer’s. The other use case is if some database warehouse or tool wants to stack all EVENTS observations into one table. Having EPOCH populated for medical history will allow a consistentency in the combined view. Finally, at any point during a study (especially for pediatric studies) it’s possible someone could simply offer up more medical history than what they previously recalled. Or a parent/guardian recalls something signficant about their child in a study which was not previously recorded. Bottom line, from a tech perspective (mapping), it’s easy just to hardcode this variable to SCREENING if that is your case and move on to more challenging endeavors. Take care, Mike. ---
**Author:** ![jing.liu](https://avatars.discourse-cdn.com/v4/letter/j/a4c791/32.png) [@jing.liu](https://forum.certara.com/u/jing.liu)\ **Post date:** [December 18, 2015, 2:10am UTC](https://forum.certara.com/t/sdtm-question-for-epoch-variable/543/14 "2015-12-18T02:10:08Z")
Thanks so much, it is very helpful. ---
**Author:** ![Liron.m](https://avatars.discourse-cdn.com/v4/letter/l/6f9a4e/32.png) [@Liron.m](https://forum.certara.com/u/Liron.m)\ **Post date:** [March 24, 2016, 7:32am UTC](https://forum.certara.com/t/sdtm-question-for-epoch-variable/543/15 "2016-03-24T07:32:00Z")
Hi, 1. How would you populate the EPOCH variable in the CM domain in the event that dates are partially known? Does one needs to impute dates in order to determine the EPOCH? 2. What if the CM dates indicates that the medication was taken long before the study screening period? for example few years before the study ever conducted, will it be accurate to mention the EPOCH as screening period? Thanks, Liron ---
**Author:** ![XML4Pharma](https://avatars.discourse-cdn.com/v4/letter/x/b2d939/32.png) [@XML4Pharma](https://forum.certara.com/u/XML4Pharma)\ **Post date:** [March 24, 2016, 10:56am UTC](https://forum.certara.com/t/sdtm-question-for-epoch-variable/543/16 "2016-03-24T10:56:01Z")
partial dates: do NOT impute EPOCH (imputations are not allowed in SDTM). medication taken long time before study start: EPOCH is an extensible codelist. So you can add your own terms. For example, you could add “PRESCREENING” to the codelist in the define.xml (do not forget to add the attribute def:ExtendedValue=“Yes”) to the “CodeListItem” or “EnumeratedItem” element, and use that for all dates (also partial ones) that are clearly before the study start date. For example “2015-01” is clearly before the study start date “2015-02-01”. As explained in [Working on and with CDISC Standards: EPOCH expected in most SDTM domains - why that is nonsense](http://cdiscguru.blogspot.com/2015/08/epoch-expected-in-most-sdtm-domains-why.html) this is a ridiculous requirement of the FDA, as EPOCH can easily be automatically be derived and added as tooltip or column by the tools that the FDA is (or should be) using. It took me less than 2 hours to do so in my visualization tool. ---
**Author:** ![Liron.m](https://avatars.discourse-cdn.com/v4/letter/l/6f9a4e/32.png) [@Liron.m](https://forum.certara.com/u/Liron.m)\ **Post date:** [March 24, 2016, 12:08pm UTC](https://forum.certara.com/t/sdtm-question-for-epoch-variable/543/17 "2016-03-24T12:08:48Z")
Thank you ---
**Author:** ![cradovsky](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@cradovsky](https://forum.certara.com/u/cradovsky)\ **Post date:** [March 29, 2016, 1:00am UTC](https://forum.certara.com/t/sdtm-question-for-epoch-variable/543/18 "2016-03-29T01:00:52Z")
Long comment to an old post dropped (belatedly saw dates) ---
**Author:** ![cradovsky](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@cradovsky](https://forum.certara.com/u/cradovsky)\ **Post date:** [March 29, 2016, 1:12am UTC](https://forum.certara.com/t/sdtm-question-for-epoch-variable/543/19 "2016-03-29T01:12:10Z")
A few comments: 1. While MH is typically collected during screening, the timing of the events captured in MH is, by definition, before the screening epoch (medical events occurring during or after screening are AEs). 2. Epoch timing periods are by definition during the study. Epoch describes the timing of the occurrence (event/intervention/finding), not the collection of the occurrence. By definition, events occurring prior to the first defined epoch (generally screening) cannot have a value for epoch. 3. From the above two comments, it is expected that MH events would not have a value for the EPOCH variable. As EPOCH is a permissible variable, when null for all records it should be omitted from the dataset. 4. This is also true for all pre-study records, so while the EPOCH variable should be in CM, it should not be populated for prior medications taken historically before the study. Pretty sure the current implementation of checks does not require EPOCH in MH. I’d be cautious with concepts like pre-screening epochs. Unless supported by study materials, this could be a misapplication of the epoch concept. Regards, Carlo ---
**Author:** ![XML4Pharma](https://avatars.discourse-cdn.com/v4/letter/x/b2d939/32.png) [@XML4Pharma](https://forum.certara.com/u/XML4Pharma)\ **Post date:** [March 29, 2016, 7:46pm UTC](https://forum.certara.com/t/sdtm-question-for-epoch-variable/543/20 "2016-03-29T19:46:30Z")
Here is a 1:1 copy of what is in the latest “Study Data Technical Conformance Guide” (October 2015): “_Please include the variables EPOCH for every clinical subject-level observation (e.g., adverse events, laboratory, concomitant medications, exposure, vital signs). This will allow the reviewer to easily determine during which phase of the trial the observation occurred (e.g., screening, on-therapy, follow-up), as well as actual intervention the subject experienced during that phase.. Inclusion of ELEMENT and ETCD (element code) is desired as well, to help reviewers understand timing of events whose durations span multiple epochs. However, because of implementation challenges associated with this request, **CDER is not yet requiring these for submission of SDTM data** _”. (see [http://www.fda.gov/downloads/ForIndustry/DataStandards/StudyDataStandards/UCM384744.pdf](http://www.fda.gov/downloads/ForIndustry/DataStandards/StudyDataStandards/UCM384744.pdf)). So the previous statement of one of the contributors “_… it’s also a variable requested by FDA in CDER Common Data Issues document and **should** be included in the dataset for these domains_” looks like a complete overinterpretation of the FDA’s position. “_Please include …_” does not sound like an obligation to me, and “_e.g. adverse events …_” does not sound like a complete list (MH is even missing in that list). So I think this rule should either disappear or be downgraded to “INFO”. BTW, reviewers should be able to derive EPOCH themselves - it is really piece of cake to do so. Best regards, Jozef [Next page](https://forum.certara.com/t/sdtm-question-for-epoch-variable/543.md?page=2)