CDISC SDTM INTERVIEW QUESTIONS

Most Important Frequently Asked Cdisc Sdtm Interview Questions

Interview Quesions on Cdisc Sdtm

Question 1. What Do You Know About Cdisc And Its Standards?

Answer :
CDISC stands for Clinical Data Interchange Standards Consortium and it is developed keeping in mind to bring great deal of efficiency in the entire drug development process. CDISC brings efficiency to the entire drug development process by improving the data quality and speed-up the whole drug development process and to do that CDISC developed a series of standards, which include Operation data Model (ODM), Study data Tabulation Model (SDTM) and the Analysis Data Model ADaM).

Question 2. Why People These Days Are More Talking About Cdsic And What Advantages It Brings To The Pharmaceutical Industry?

Answer :
Generally speaking, Only about 30% of programming time is used to generate statistical results with SAS®, and the rest of programming time is used to familiarize data structure, check data accuracy, and tabulate/list raw data and statistical results into certain formats. This non-statistical programming time will be significantly reduced after implementing the CDISC standards.

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Question 3. What Are The Challenges As Sas Programmer You Think You Will Face When You First Implement Cdisc Standards In You Company?

Answer :
With the new requirements of electronic submission, CRT datasets need to conform to a set of standards for facilitating reviewing process. They no longer are created solely for programmers convenient. SDS will be treated as specifications of datasets to be submitted, potentially as reference of CRF design.
Therefore, statistical programming may need to start from this common ground. All existing programs/macros may also need to be remapped based on CDISC so one can take advantage to validate submission information by using tools which reviewer may use for reviewing and to accelerate reviewing process without providing unnecessary data,tables and listings.
With the new requirements from updating electronic submission and CDISC implementation, understanding only SAS® may not be good enough to fulfill for final deliverables. It is a time to expand and enhance the job skills from various aspects under new change so that SAS® programmers can take a competitive advantage, and continue to play a main role in both statistical analysis and reporting for drug development.

Question 4. What Are The Capabilities Of Proc Cdisc 2?

Answer :
PROC CDISC performs the following checks on domain content of the source:
Verifies that all required variables are present in the data set Reports as an error any variables in the data set that are not defined in the domain Reports a warning for any expected domain variables that are not in the data set
Notes any permitted domain variables that are not in the data set Verifies that all domain variables are of the expected data type and proper length Detects any domain variables that are assigned a controlled terminology specification by the domain and do not have a format assigned to them.
The procedure also performs the following checks on domain data content of the source on a per observation basis:
Verifies that all required variable fields do not contain missing values Detects occurrences of expected variable fields that contain missing values Detects the conformance of all ISO-8601 specification assigned values; including date, time, date time, duration, and interval types Notes correctness of yes/no and yes/no/null responses

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Question 5. What Are The Different Approaches For Creating The Sdtm 3?

Answer :
There are 3 general approaches to create the SDTM datasets:
1. Build the SDTM entirely in the CDMS,
2. Build the SDTM entirely on the “back-end” in SAS,
3. or take a hybrid approach and build the SDTM partially in the CDMS and partially in SAS.
BUILD THE SDTM ENTIRELY IN THE CDMS:
It is possible to build the SDTM entirely within the CDMS. If the CDMS allows for broad structural control of the underlying database, then you could build your eCRF or CRF based clinical database to SDTM standards.
Advantages:
- Your “raw” database is equivalent to your SDTM which provides the most elegant solution.
- Your clinical data management staff will be able to converse with endusers/sponsors about the data easily since your clinical data manager and the und-user/sponsor will both be looking at SDTM datasets.
- As soon as the CDMS database is built, the SDTM datasets are available.
Disadvantages:
• This approach may be cost prohibitive. Forcing the CDMS to create the SDTM structures may simply be too cumbersome to do efficiently.
• Forcing the CDMS to adapt to the SDTM may cause problems with the operation of the CDMS which could reduce data quality.
BUILD THE SDTM ENTIRELY ON THE “BACK-END” IN SAS
Assuming that SAS is not your CDMS solution, another approach is to take the clinical data from your CDMS and manipulate it into the SDTM with SAS programming.
Advantages:
- The great flexibility of SAS will let you transform any proprietary CDMS structure into the SDTM. You do not have to work around the rigid constraints of the CDMS.
- Changes could be made to the SDTM conversion without disturbing clinical data management processes.
- The CDMS is allowed to do what it does best which is to enter, manage, and clean data.
Disadvantages:
• There would be additional cost to transform the data from your typical CDMS structure into the SDTM.Specifications, programming, and validation of the SAS programming transformation would be required.
• Once the CDMS database is up, there would then be a subsequent delay while the SDTM is created in SAS.This delay would slow down the production of analysis datasets and reporting. This assumes that you follow the linear progression of CDMS ->
SDTM -> analysis datasets (ADaM).
• Since the SDTM is a derivation of the “raw” data, there could be errors in translation from the “raw” CDMS data to the SDTM.
• Your clinical data management staff may be at a disadvantage when speaking with end-users/sponsors about the data since the data manager will likely be looking at the CDMS data and the sponsor will see SDTM data.
BUILD THE SDTM USING A HYBRID APPROACH
Again, assuming that SAS is not your CDMS solution, you could build some of the SDTM within the confines of the CDMS and do the rest of the work inSAS. There are things that could be done easily in the CDMS such as naming data tables the same as SDTM domains, using SDTM variable names in the CTMS, and performing simple derivations (such as age) in the CDMS. More complex SDTM derivations and manipulations can then be performed in SAS.
Advantages:
- The changes to the CDMS are easy to implement.
- The SDTM conversions to be done in SAS are manageable and much can be automated.
Disadvantages:
- There would still be some additional cost needed to transform the data from the SDTM-like CDMS structure into the SDTM. Specifications, programming, and validation of the transformation would be required.
- There would be some delay while the SDTM-like CDMS data is converted to the SDTM.
- Your clinical data management staff may still have a slight disadvantage
when speaking with endusers/ sponsors about the data since the clinical data manager will be looking at the SDTM-like data and the sponsor will see the true SDTM data.

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Question 6. Can You Tell Me How To Do The Mapping For Existing Domains?

Answer :
First step is the comparison of metadata with the SDTM domain metadata. If the data getting from the data management is in somewhat compliance to SDTM metadata, use automated mapping as the Ist step.
If the data management metadata is not in compliance with SDTM then avoid auto mapping. So do manual mapping the datasets to SDTM datasets and the mapping each variable to appropriate domain.
The whole process of mapping include: *Read in the corporate data standards into a database table.
- Assign a CDISC domain prefix to each database module.
- Attach a combo box containing the SDTM variable for the selected domain to a new mapping variable field.
- Search each module, and within each module select the most appropriate CDISC variable.
- Then search for variables mapped to the wrong type Character not equal to Character; Numeric not equal to Numeric.
- Review the mapping to see if any conflicts are resolvable by mapping to a more appropriate variable.
- We need to verify that the mapped variable is appropriate for each role.
- Then finally we have to ensure all ‘required’ variables are present in the domain6.

Question 7. What Do You Know About Sdtm Implementation Guide, Have You Used It, If You Have Can You Tell Me Which Version You Have Used So Far?

Answer :
SDTM Implementation guide provides documentation on metadata (data of data) for the domain datasets that includes filename, variable names, type of variables and its labels etc. I have used SDTM implementation guide versions 3.1.1/3.1.2

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Question 8. Can You Identify Which Variables Should We Have To Include In Each Domain?

Answer :
SDTM implementation guide V 3.1.1/V 3.1.2 specifies each variable is being included in one of the 3 types.
REQUIRED : They must be included in the data set structure and should not have a missing value for any observation.
EXPECTED :These variables must be included in the data set; however it is permissible to have missing values.
PERMISSIBLE : These variables are not a required part of the domain and they should not be included in the data set structure if the information they were designed to contain was not collected.

Question 9. Can You Give Some Examples For Mapping *6?

Answer :
Here are some examples for SDTM mapping:
- Character variables defined as Numeric
- Numeric Variables defined as Character
- Variables collected without an obvious corresponding domain in the CDISC SDTM mapping. So must go into SUPPQUAL
- Several corporate modules that map to one corresponding domain in CDISC SDTM.
- Core SDTM is a subset of the existing corporate standards
- Vertical versus Horizontal structure, (e.g. Vitals)
- Dates – combining date and times; partial dates.
- Data collapsing issues e.g. Adverse Events and Concomitant Medications.
- Adverse Events maximum intensity
- Metadata needed to laboratory data standardization.

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Question 10. Explain The Process Of Sdtm Mapping?

Answer :
A list of basic variable mappings is given below *4.
DIRECT: a CDM variable is copied directly to a domain variable without any changes other than assigning the CDISC standard label.
RENAME: only the variable name and label may change but the contents remain the same.
STANDARDIZE: mapping reported values to standard units or standard terminology
REFORMAT: the actual value being represented does not change, only the format in which is stored changes, such as converting a SAS date to an ISO8601 format character string.
COMBINING: directly combining two or more CDM variables to form a single SDTM variable.
SPLITTING: a CDM variable is divided into two or more SDTM variables.
DERIVATION: creating a domain variable based on a computation, algorithm, series of logic rules or decoding using one or more CDM variables.