CDISC data standards
CDISC stands for Clinical Data Interchange Standards Consortium. CDISC provides several interrelated standards, each addressing a specific stage of the data lifecycle Figure 1. Each standard has an Implementation Guide (IG) that shows exactly how to apply that standard practically, e.g. SDTMIG for SDTM. All the implementations have version numbers that are important to keep track of.
CDISC also provides TAUGs (Therapeutic Area User Guides). A TAUG is a document providing guidance on applying CDISC standards to a specific therapeutic area (oncology, diabetes, CNS, etc.).
CDASH
CDASH (Clinical Data Acquisition Standards Harmonization) standardizes how data are entered into case report forms (CRFs) at clinical sites.
SDTM
SDTM (Study Data Tabulation Model) organizes the data from CDASH into submission-ready datasets. It includes different domains/datasets (e.g., exposure, and lab-values) and controlled terminology (e.g., how to name variables).
General Observation Classes
General Observation Classes are high-level classifications within SDTM that group domains based on the type of data they contain.
There are three general observation classes: Interventions, Events, and Findings. There is also a fourth observation class: Special purpose.
Observation classes are then grouped into domains, organized around a particular topic. Each “domain” is usually a separate dataset; for example, EX can be a dataset containing exposure (dosing) data. However, a domain can also be split into multiple datasets. A typical example is splitting the Laboratory Test Results (LB) domain due to size.
Observation Class | Domain Name | Domain Abbreviation |
---|---|---|
Interventions | Procedure agents | AG |
Concomitant/prior medications | CM |
|
Exposure | EX |
|
Exposure as collected | EC |
|
Meal data | ML |
|
Procedures | PR |
|
Substance use | SU |
|
Events | Adverse events | AE |
Biospecimen events | BE |
|
Clinical events | CE |
|
Disposition | DS |
|
Healthcare encounters | HO |
|
Medical history | MH |
|
Protocol deviations | DV |
|
Findings | Product/drug accountability | DA |
Death details | DD |
|
ECG test results | EG |
|
Inclusion/Exclusion criteria not met | IE |
|
Biospecimen findings | BS |
|
Cell phenotype findings | CP |
|
Genomics findings | GF |
|
Immunogenicity specimen assessments | IS |
|
Laboratory test results | LB |
|
Microbiology specimen | MB |
|
Microbiology susceptibility | MS |
|
Microscopic findings | MI |
|
PK concentrations | PC |
|
PK parameters | PP |
|
Morphology | MO |
|
Cardiovascular system findings | CV |
|
Musculoskeletal system findings | MK |
|
Nervous system findings | NV |
|
Ophthalmic examinations | OE |
|
Reproductive system findings | RP |
|
Respiratory system findings | RE |
|
Urinary system findings | UR |
|
Physical examination | PE |
|
Functional tests | FT |
|
Questionnaires | QS |
|
Disease response and clinical classification | RS |
|
Subject characteristics | SC |
|
Subject status | SS |
|
Tumor/lesion identification | TU |
|
Tumor/lesion results | TR |
|
Vital signs | VS |
|
Findings about events or interventions | FA |
|
Skin response | SR |
|
Special Purpose | Comments | CO |
Demographics | DM |
|
Subject elements | SE |
|
Subject disease milestones | SM |
|
Subject visits | SV |
SDTM variables
Variables are classified as required, expected, or permissible for each domain.
Identifier
- STUDYID
- DOMAIN
- USUBJID
- –SEQ
Topic
Contain the focus of the observation.
- –TRT
- –TERM
- –TESTCD
Qualifier
Qualifiers provide additional information about the topic variables.
- Grouping
- Result
- Synonym
- Record
- Variable
Timing
Describes the timing of the observation.
- Date/times
- Study days
- Durations
- Intervals
- Visits
- Time points
- Relative times
ADaM
ADaM (Analysis Data Model) takes SDTM data and transforms it into datasets suitable for statistical analysis. It contains derived datasets used for tables, listings, figures. Like SDTM it is organized into different domains/datasets, each with its specific setup.
https://www.cdisc.org/system/files/members/standard/foundational/ADaMIG_v1.3.pdf
ADaM Standard data structures
- ADSL: Subject-level analysis dataset
- One record per subject
- BDS: Basic data structure
- One (or more) record per subject/parameter/timepoint
- OCCDS: Occurrence data structure
- Designed for counting occurrences
- ADaM Other data structure
ADaM variable conventions
General variable conventions
All ADaM variable names must be no more than 8 characters in length, start with a letter (not underscore), and be composed only of letters (A–Z), underscore ( _ ), and numerals (0–9).
ADaM adheres to a principle of harmonization known as “same name, same meaning, same values.”
Generally, suppose an SDTM character variable is converted to a numeric variable in an ADaM dataset. In that case, it should be named as it is in the SDTM dataset with an “N” suffix added.
In a pair of corresponding variables (e.g., TRTP and TRTPN), the primary or most commonly used variable does not have the suffix or extension (i.e., N for numeric or C for character). The relevant suffix is used only on the name of the secondary member of the variable pair.
Variables whose names end in FL are character flag (or indicator) variables.
Variables whose names end in GRy, Gy, or CATy are grouping variables, where “y” refers to the grouping scheme or algorithm (not the category within the grouping).
It is recommended that producer-defined grouping or categorization variables begin with the name of the variable being grouped and end in GRy (e.g., variable ABCGRy is a character description of a grouping or categorization of the values from the ABC variable for analysis purposes).
Timing variable conventions
Variables whose names end in DT are numeric dates.
Variables whose names end in DTM are numeric datetimes.
Variables whose names end in TM are numeric times.
Names of timing start variables end with an S followed by the characters indicating the type of timing (i.e., SDT, STM, SDTM).
Names of timing end variables end with an E followed by the characters indicating the type of timing (i.e., EDT, ETM, EDTM)
Variables whose names end in DY are relative day variables.
Variable naming fragments
Fragment | Notes |
---|---|
GRy | Grouping variables |
Gy | Abbreviation of GRy |
FL | Flag/indicator |
DT | Numeric date |
TM | Numeric time |
DTM | Numeric datetime |
DTF | Date imputation flag |
TMF | Time imputation flag |
DY | Relative days (does not include day 0) |
Fragment | Notes |
---|---|
BL | Baseline |
CHG | Change |
FU | Follow-up |
OT | On treatment |
RU | Run-in |
SC | Screening |
TA | Taper |
TI | Titer |
U | Units |
WA | Washout |
ADSL variables
Variable | Notes |
---|---|
Variable | Notes |
---|---|
BDS variables
Analysis-enabling variables
SEND
SEND (Standard for Exchange of Nonclinical Data) mirrors SDTM but for non-clinical (animal) studies, describing how data is organized.