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SDTM Programming Interview Questions and Answers

1. What is SDTM, and why is it important in clinical trials?

Answer: SDTM (Study Data Tabulation Model) is a standardized format for organizing and submitting clinical trial data to regulatory authorities, such as the FDA. It is important because it ensures that data is structured consistently across studies, facilitating data review, analysis, and submission.

2. What are the key components of an SDTM dataset?

Answer: The key components of an SDTM dataset include:

Domains: Specific datasets like DM (Demographics), AE (Adverse Events), LB (Laboratory), etc.
Variables: Each domain has standard variables such as USUBJID (Unique Subject Identifier), DOMAIN, VISIT, and others.
Value-Level Metadata: Defines the structure and content of the variables.
Controlled Terminology: Standard terms and codes used in SDTM datasets.

3. What is the purpose of the DM (Demographics) domain in SDTM?

Answer: The DM domain in SDTM provides basic demographic data for each subject in the study, including variables like age, sex, race, and country. It serves as the cornerstone for linking all other domains in the study.

4. Explain the structure of the AE (Adverse Events) domain in SDTM.

Answer: The AE domain captures information about adverse events experienced by subjects during the clinical trial. Key variables include:

AEDECOD: Coded adverse event term using a standard dictionary like MedDRA.
AESTDTC: Start date of the adverse event.
AEENDTC: End date of the adverse event.
AESER: Indicator of whether the event was serious.

5. What is the role of the SUPPQUAL domain in SDTM?

Answer: The SUPPQUAL (Supplemental Qualifiers) domain is used to store non-standard variables that cannot be directly accommodated in the core SDTM domains. It is linked to the parent domain through the RDOMAIN, IDVAR, and IDVARVAL variables.

6. How do you handle missing data in SDTM datasets?

Answer: Handling missing data in SDTM involves:

Leaving the variable blank if the data is truly missing.
Using controlled terminology like “NOT DONE” or “UNKNOWN” when appropriate.
Ensuring that missing data is documented in the define.xml file.

7. What is the purpose of the RELREC domain in SDTM?

Answer: The RELREC (Related Records) domain is used to describe relationships between records in different SDTM domains. For example, it can link an adverse event record with a concomitant medication record.

8. How do you create a VS (Vital Signs) domain in SDTM?

Answer: To create a VS domain in SDTM, you:

Extract relevant data from the source datasets (e.g., vital signs measurements).
Map the data to standard SDTM variables like VSTESTCD (Vital Signs Test Code), VSORRES (Original Result), and VSDTC (Date/Time of Collection).
Ensure that the data is structured according to the SDTM guidelines.

9. What is the difference between SDTM and ADaM datasets?

Answer: SDTM datasets are used for organizing and standardizing raw clinical trial data, whereas ADaM (Analysis Data Model) datasets are derived from SDTM datasets and are designed specifically for statistical analysis. SDTM focuses on data collection and standardization, while ADaM focuses on analysis and interpretation.

10. Explain the significance of controlled terminology in SDTM.

Answer: Controlled terminology in SDTM ensures consistency and standardization in how data is represented across studies. It involves using predefined lists of terms and codes (e.g., MedDRA for adverse events) to standardize variables across datasets.

11. What is the QS (Questionnaires) domain in SDTM?

Answer: The QS domain in SDTM is used to capture data from questionnaires, surveys, or patient-reported outcomes. It includes variables like QSTESTCD (Questionnaire Test Code), QSTEST (Test Name), and QSORRES (Original Result).

12. How do you handle date and time variables in SDTM?

Answer: Date and time variables in SDTM are handled using ISO 8601 formats (e.g., YYYY-MM-DD for dates, and HH:MM:SS for times). If time is not collected, it should be indicated as “UNK” (unknown). The DTC suffix is used to indicate date and time (e.g., AESTDTC for Adverse Event Start Date/Time).

13. What is the significance of the VISITNUM variable in SDTM?

Answer: VISITNUM is a key variable in SDTM that identifies the visit number associated with a particular record. It is used to link records across different domains and is critical for tracking the timing of events and assessments.

14. How do you handle multiple records per subject in SDTM?

Answer: Multiple records per subject are handled in SDTM by using variables like SEQ (Sequence Number) and ensuring that each record has a unique combination of USUBJID and SEQ within a domain. This ensures that each record can be uniquely identified.

15. What is the LB (Laboratory) domain in SDTM, and what key variables does it contain?

Answer: The LB domain in SDTM captures laboratory test results for subjects. Key variables include:

LBTESTCD: Laboratory Test Code (e.g., GLUC for glucose).
LBORRES: Original Result as collected.
LBORRESU: Original Result Units.
LBDTC: Date/Time of the lab test.

16. What is the significance of the DEFINE.XML file in SDTM submissions?

Answer: The DEFINE.XML file is a critical component of SDTM submissions. It serves as a metadata document that describes the structure, content, and origin of each variable in the submitted datasets. It ensures that regulatory reviewers can understand and interpret the data correctly.

17. How do you handle protocol deviations in SDTM?

Answer: Protocol deviations in SDTM are typically handled in the DV (Protocol Deviations) domain. This domain captures details about deviations from the study protocol, including the nature of the deviation, the subject involved, and the timing of the deviation.

18. Explain the role of the EX (Exposure) domain in SDTM.

Answer: The EX domain in SDTM captures data on the exposure of subjects to study treatments. Key variables include:

EXTRT: Name of the treatment.
EXDOSE: Dose administered.
EXDOSU: Dose units.
EXSTDTC: Start date/time of administration.

19. What is the difference between –ORRES and –STRESC variables in SDTM?

Answer: –ORRES (Original Result) captures the result as it was originally collected in the study, while –STRESC (Standardized Result in Character Format) represents the result in a standardized format, often converted to a common unit or scale to allow for easier comparison across subjects and studies.

20. How do you ensure data quality and integrity in SDTM datasets?

Answer: Ensuring data quality and integrity in SDTM datasets involves:

Performing validation checks to ensure that data conforms to SDTM standards.
Using controlled terminology consistently across datasets.
Documenting all data transformations and ensuring traceability from source data to SDTM.
Conducting thorough peer reviews and audits of SDTM datasets before submission.

21. What is the EG (Electrocardiogram) domain in SDTM, and what are its key variables?

Answer: The EG domain in SDTM captures electrocardiogram (ECG) data for subjects. Key variables include:

EGTESTCD: ECG Test Code (e.g., HR for heart rate).
EGORRES: Original Result as collected.
EGDTC: Date/Time of the ECG test.

22. How do you create an SV (Subject Visits) domain in SDTM?

Answer: To create an SV domain in SDTM, you:

Extract visit-related data from the source datasets.
Map the data to standard SDTM variables like VISITNUM (Visit Number), VISIT (Visit Name), and SVSTDTC (Start Date/Time of Visit).
Ensure that the data is structured according to the SDTM guidelines.

23. What is the role of the TA (Trial Arms) domain in SDTM?

Answer: The TA domain in SDTM defines the different arms or treatment groups in the clinical trial. It includes information about the planned sequence of visits, treatments, and assessments for each arm of the study.

24. How do you manage datasets with multiple visits in SDTM?

Answer: Datasets with multiple visits are managed in SDTM by ensuring that each visit is uniquely identified using the VISITNUM and VISIT variables. The VISITNUM variable provides a numeric identifier, while the VISIT variable provides a descriptive name for each visit.

25. Explain the purpose of the SC (Subject Characteristics) domain in SDTM.

Answer: The SC domain in SDTM captures subject characteristics that are not part of the core demographics but are relevant to the study. This may include variables like smoking status, alcohol use, or genetic markers.

26. How do you convert raw data into SDTM format?

Answer: Converting raw data into SDTM format involves:

Mapping raw data variables to standard SDTM variables.
Applying controlled terminology to ensure consistency.
Restructuring the data to fit the SDTM domain structures.
Validating the converted data against SDTM standards to ensure accuracy and compliance.

27. What is the CO (Comments) domain in SDTM, and when is it used?

Answer: The CO domain in SDTM captures free-text comments related to a subject or study event. It is used when additional explanatory information is needed that does not fit into other SDTM domains.

28. How do you handle multiple treatments in the EX domain?

Answer: Handling multiple treatments in the EX domain involves:

Recording each treatment administration as a separate record in the EX domain.
Using the EXTRT variable to specify the treatment name and ensuring that each administration event has a unique EXSEQ (Sequence Number).
Documenting any overlapping or sequential treatments appropriately.

29. What is the role of the PR (Procedures) domain in SDTM?

Answer: The PR domain in SDTM captures information about medical procedures performed on subjects during the study. Key variables include PRTRT (Procedure Name), PRSTDTC (Procedure Start Date/Time), and PRENDTC (Procedure End Date/Time).

30. How do you validate SDTM datasets before submission?

Answer: Validating SDTM datasets before submission involves:

Running compliance checks using tools like Pinnacle 21 or the SAS Clinical Standards Toolkit.
Verifying that all required variables are present and correctly formatted.
Ensuring that controlled terminology is applied consistently.
Conducting peer reviews and audits to identify and correct any errors.

31. What is the CE (Clinical Events) domain in SDTM?

Answer: The CE domain in SDTM captures clinical events that are not classified as adverse events but are significant to the study. Examples include hospitalizations, surgeries, or disease-related events. Key variables include CETERM (Event Term) and CEDTC (Event Date/Time).

32. How do you handle data from unscheduled visits in SDTM?

Answer: Data from unscheduled visits in SDTM is typically included in the relevant domains with a VISITNUM value indicating an unscheduled visit. The VISIT variable may also be populated with a descriptive name like “Unscheduled Visit.”

33. What is the role of the TI (Trial Inclusion/Exclusion Criteria) domain in SDTM?

Answer: The TI domain in SDTM captures information about the inclusion and exclusion criteria used to select subjects for the study. It includes variables like TICAT (Inclusion/Exclusion Category) and TIDESC (Description of Criterion).

34. How do you handle concomitant medications in SDTM?

Answer: Concomitant medications are handled in the CM (Concomitant Medications) domain in SDTM. This domain captures details about any medications taken by subjects during the study that are not part of the study treatment. Key variables include CMTRT (Medication Name), CMSTDTC (Start Date/Time), and CMENDTC (End Date/Time).

35. What is the IE (Inclusion/Exclusion Criteria Not Met) domain in SDTM?

Answer: The IE domain in SDTM captures information about subjects who did not meet one or more inclusion or exclusion criteria for the study. It includes variables like IETESTCD (Test Code), IETEST (Test Name), and IESTDTC (Date/Time of Assessment).

36. Explain the purpose of the TR (Tumor Response) domain in SDTM.

Answer: The TR domain in SDTM captures data related to tumor assessments in oncology studies. It includes information on the size, location, and response of tumors to treatment. Key variables include TRTESTCD (Test Code), TRORRES (Original Result), and TRDTC (Date/Time of Assessment).

37. How do you handle medical history data in SDTM?

Answer: Medical history data is handled in the MH (Medical History) domain in SDTM. This domain captures information about relevant medical conditions or events that occurred before the subject entered the study. Key variables include MHTERM (Medical History Term) and MHSTDTC (Start Date/Time).

38. What is the FA (Findings About) domain in SDTM, and how is it used?

Answer: The FA domain in SDTM is used to capture additional findings related to other domains. It allows for the recording of results or conclusions derived from other data, such as findings related to an adverse event or a tumor. Key variables include FATESTCD (Test Code) and FAORRES (Original Result).

39. How do you handle vital signs data with multiple measurements per visit in SDTM?

Answer: Vital signs data with multiple measurements per visit is handled in the VS domain by creating multiple records for each measurement, differentiated by the VISITNUM and VSSEQ (Sequence Number) variables. Each record corresponds to a single measurement at a specific time.

40. What is the role of the MI (Microscopic Findings) domain in SDTM?

Answer: The MI domain in SDTM captures microscopic findings from tissue or fluid samples collected during the study. It includes details about the histopathological assessment of samples, with key variables like MITESTCD (Test Code), MIORRES (Original Result), and MIDTC (Date/Time of Assessment).

41. How do you create a trial summary dataset in SDTM?

Answer: A trial summary dataset in SDTM is typically created in the TS (Trial Summary) domain. This domain provides an overview of the study, including details like the study design, objectives, and key dates. Variables include TSPARMCD (Parameter Code) and TSVAL (Parameter Value).

42. How do you handle adverse events with missing start or end dates in SDTM?

Answer: Adverse events with missing start or end dates in SDTM are handled by leaving the AESTDTC (Start Date/Time) or AEENDTC (End Date/Time) variable blank if the date is truly unknown. If partial dates are available, they are represented using ISO 8601 format with missing parts indicated by dashes (e.g., “2023-05-“).

43. What is the SV (Subject Visits) domain in SDTM, and what is its purpose?

Answer: The SV domain in SDTM captures information about the visits that subjects attended during the study. It includes details like the visit number, visit name, and the start and end dates of the visit. The SV domain is used to link other domains that contain visit-related data, ensuring consistency across the study.

44. How do you handle lab data that is below the limit of detection in SDTM?

Answer: Lab data that is below the limit of detection is handled in SDTM by using controlled terminology to indicate that the value is below the detection limit. The LBORRES variable may contain a value like ”

45. Explain the purpose of the MO (Morphology) domain in SDTM.

Answer: The MO domain in SDTM captures data related to the morphology of tumors or other abnormalities observed in imaging studies. It includes details about the size, shape, and characteristics of the observed morphology. Key variables include MOTESTCD (Test Code) and MOORRES (Original Result).

46. How do you ensure compliance with regulatory requirements when creating SDTM datasets?

Answer: Ensuring compliance with regulatory requirements when creating SDTM datasets involves:

Following the CDISC SDTM Implementation Guide (IG) to structure the datasets.
Using controlled terminology consistently across datasets.
Validating the datasets using tools like Pinnacle 21 to check for compliance with regulatory rules.
Preparing comprehensive metadata documentation, including DEFINE.XML files, to describe the datasets.

47. What is the role of the TU (Tumor Identification) domain in SDTM?

Answer: The TU domain in SDTM captures information about the identification and classification of tumors in oncology studies. It includes details about the tumor’s location, size, and type, with key variables like TUTESTCD (Test Code) and TUORRES (Original Result).

48. How do you handle data from multiple study sites in SDTM?

Answer: Data from multiple study sites in SDTM is handled by ensuring that each subject is linked to their respective site using the SITEID variable in the DM domain. This variable allows for the identification and differentiation of data from different study sites.

49. What is the RP (Reproductive System Findings) domain in SDTM?

Answer: The RP domain in SDTM captures findings related to the reproductive system, including assessments of fertility, pregnancy, and related outcomes. It includes variables like RPTESTCD (Test Code) and RPORRES (Original Result).

50. How do you handle adverse events that occur after the study ends in SDTM?

Answer: Adverse events that occur after the study ends are typically captured in the AE domain, with the AEENDTC variable indicating the date of the event. If the event occurs after the study’s official end date, this should be noted in the AE domain, and the data should be handled according to the study protocol and regulatory requirements.