1. Medical History Collection Period
    1. Applicants should define the appropriate collection period for medical history in the protocol. The evaluation interval may be provided in the tabulation variable MHEVLINT or MHEVINTX. These intervals are populated by the applicant in the tabulation MH dataset. These intervals may be printed on the CRF as instruction text. 
  2. Medical History Coding
    1. Applicants who code medical history should use appropriate dictionary variables for the coding. 
    2. Coding variables are not a data collection field that will appear on the CRF itself; applicants will populate this through the coding process. When MedDRA is used as the coding dictionary, the MedDRA coding variables are included in the tabulation dataset.
    3. If coding using MedDRA, it is recommended that coding be done during the execution phase of a study rather than after it is completed, as this facilitates efficient resolution of any coding queries.
    4. For uncoded medical history, an applicant-defined categorization of medical history events is recommended. One approach is to use the MHCAT variable.  
  3. Date of Collection (DAT) 
    1. This is the date that the data were recorded, and not the date that the condition started or the event occurred. The date of collection can be derived from the date of the visit.
  4. Relative Timing Variables
    1. The date of data collection in conjunction with a collected time point anchor date and the MHONGO Collection fields would determine how the tabulation relative timing variables would be populated.
    2. The MHONGO field does not map directly to a tabulation variable, but it may be used to derive a value into a tabulation-based relative timing variable (e.g., MHENRF, MHENRTPT). When populating MHENRF, if the value of MHONGO is "Y", the values of "DURING", "AFTER", or "DURING/AFTER" may be derived. When populating MHENRTPT, if the value of MHONGO is "Y", the value of "ONGOING" may be derived. MHENRTPT must refer to a time-point anchor described in MHENTPT.
    3. MHONGO is a special-use case of "Yes/No", where the question is usually presented as a single possible response of "Yes" when there is no applicable end date at time of collection. In this case, if the box is checked and the end date is blank, MHONGO is "Yes". If the box is not checked and an end date is present, MHONGO is "No". 
    4. MHPRIOR can be added to this domain from the CDASH Model and used when the applicant elects not to collect start dates (even partial dates) on the MH CRF. The applicant would derive a value into a tabulation relative Timing variable such as MHSTRF or MHSTRTPT. When populating MHSTRF, if the value of MHPRIOR is “Y”, the value of “BEFORE” may be derived. When populating MHSTRTPT, if the value of MHPRIOR is “Y”, the value of “BEFORE” may be derived. Note: MHSTRTPT must refer to a “time point anchor” as described in MHSTTPT.
  5.  Start and End Dates
    1. Partial dates are commonly collected in MH where the subject may not remember the complete date of when a medical history condition started or ended. The applicant may choose to capture a complete date or any variation thereof (e.g., month and year or year).
  6. Medical History Event Type
    1. Medical History Event Type (MHEVDTYP) is used to specify the aspect of the medical condition or event by which its start date is defined. This variable (MHEVDTYP) is only to be used in the MH domain. This variable is used when the CRF records "multiple" dates such as the date when the condition was diagnosed, when symptoms were first reported prior to diagnosis, when the subject had a relapse, or when the infection associated with the diagnosis was reported. Example values for MHEVDTYP include DIAGNOSIS, SYMPTOMS, RELAPSE, and INFECTION.