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© 2021 Clinical Data Interchange Standards Consortium, Inc. All rights reserved. 

1 Introduction

This document describes the CDISC implementation of the Psoriasis Area and Severity Index Version 2 (PASI V2) instrument.

There is no known standard case report form (CRF) available for this instrument. CDISC created this CRF to represent the instrument, which CDISC believes is in the public domain. This is not an endorsement of the instrument. The creation of this instrument was based on input from PASI V2 subject matter experts. Sponsors may create this instrument’s CRF using their style guidelines, but they need to maintain the wording and order of the questions/items and responses as described on the CRF.

The representation of data collected for this instrument is based on the Study Data Tabulation Model Implementation Guide (SDTMIG) Disease Response and Clin Classification (RS) domain model, which can be found on the CDISC website at: https://www.cdisc.org/standards/foundational/sdtmig.

These specific implementation details for this instrument are meant to be used in conjunction with the SDTMIG. All CDISC Quesionnaires, Ratings and Scales (QRS) documentation packages can be found on the CDISC website at: https://www.cdisc.org/standards/foundational/qrs.

The CDISC Intellectual Property Policy can be found on the CDISC website at: https://www.cdisc.org/about/bylaws.

1.1 Representations and Warranties, Limitations of Liability, and Disclaimers

This document is a supplement to the SDTMIG for Human Clinical Trials and is covered under Appendix F of that document, which describes representations, warranties, limitations of liability, and disclaimers. Please see Appendix F of the SDTMIG for a complete version of this material.

CDISC specifies how to structure the data that has been collected in a database, not what should be collected or how to conduct clinical assessments or protocols. CDISC disclaims any liability for your use of this material.

Although the United States Food and Drug Administration (US FDA) has provided input with regard to this supplement, this input does not constitute US FDA endorsement of any particular instrument.

2 Copyright Status

CDISC believes this instrument to be in the public domain, but you should perform your own assessment. CDISC has included the PASI V2 in the CDISC library of QRS data standards supplements. Hence, CDISC developed RSTESTCD and RSTEST for each item based on the actual text on the instrument. There may be many versions of this instrument. CDISC has chosen to use this version as the data standard.

The CDISC documentation of this instrument consists of: (1) controlled terminology, (2) standard database structure with examples, and (3) CRF(s) annotated with the CDISC SDTMIG variables with submission values. 

Note: CDISC Controlled Terminology is maintained by National Cancer Institute (NCI) Enterprise Vocabulary Services (EVS). The most recent version should be accessed through the CDISC website at: https://www.cdisc.org/standards/terminology/controlled-terminology.

Reference for the PASI V2:

Feldman SR, Krueger GG. Psoriasis assessment tools in clinical trials. Ann Rheum Dis. 2005;64(Suppl 2):ii65–ii73.

3 The RS Domain Model

3.1 Assumptions for the RS Domain Model

All assumptions and business rules described in the SDTMIG RS domain are applicable to this supplement. Additional assumptions specific to the PASI V2 are listed below.

The PASI V2 is a tool used to assess the severity of psoriasis. The PASI V2 breaks the body up into 4 sections (i.e., head, trunk, upper extremity, lower extremity) and assesses symptom severity and the percentage of each area affected by psoriasis. The symptoms are rated on a 5-point scale and the area is rated on a 7-point scale. Subscores for each section of the body and a total score are also captured.

1. The scale points for the symptoms (i.e., erythema/redness, thickness/induration, desquamation/scaling) include a numeric rating (0-4) and a definition of what is represented by the rating (e.g., 0 = "None"). For the PASI V2, RSORRES is populated with the text description while the numeric rating is represented in the standardized character and numeric result variables RSSTRESC and RSSTRESN.

   1. CDISC created a CRF based on input from subject-matter experts and the Feldman reference article.
      
   2. The Feldman article uses the symptom terms "erythema", "induration" and "scale". However, the terms "redness", "thickness" and "desquamation" are also used regularly, therefore, both version of the symptom terms are used on the CDISC created CRF and in the terminology for RSTEST.
      
2. The scale points for the area include a numeric rating (0-6) and a definition of what is represented by the rating (e.g., 0 = "No Involvement"). For the area, RSORRES is populated with the text description while the numeric rating is represented in the standardized character and numeric result variables RSSTRESC and RSSTRESN.
   

3. The PASI V2 instrument includes subscores and a total score that are considered as captured data on the CRF and are not considered as derived in the example below. These scores may be submitted in SDTM or derived in the Analysis Data Model (ADaM) per scoring instructions from the Feldman reference.

   1. If operationally defined by the sponsor, it is the sponsor's responsibility to set the --DRVFL flag based on their eCRF process to derive subtotals and total scores. An investigator-derived score will be considered a captured score and not flagged. When subtotal and total scores are derived by the sponsor, the derived flag (--DRVFL) is set to "Y". However, when the subtotal and total scores are received from a central provider or vendor, the value would go into --ORRES and --DRVFL would be null (see SDTMIG Section 4.1.8.1, Origin Metadata for Variables).

   2. If scores are received by the sponsor, it is recommended that they are submitted to SDTM and verified in ADaM.

   3. 
      

4. Records are created in rs.xpt for every item on the instrument: 

   1. For items with no data, RSORRES, RSSTRESC, and RSSTRESN are all missing and RSSTAT = "NOT DONE".  If the reason is known then that reason is represented in RSREASND (e.g., RSREASND = "REFUSED". If the reason is unknown, then RSSTAT = "NOT DONE" and RSREASND is missing.

5. Terminology

   1. RSCAT, RSTESTCD, and RSTEST values are included in CDISC Controlled Terminology.

   2. A full list of value sets for the result field is provided in Section 4, SDTM Mapping Strategy.

3.2 Example for the PASI V2 RS Domain Model

The PASI V2 example below shows the terminology used to implement the instrument in the RS domain. This example shows the data for 1 subject collected at the baseline visit for the PASI V2 instrument. The example uses CDISC Controlled Terminology for RSTESTCD, RSTEST, and RSCAT. All original results are represented with preferred terminology in RSORRES. This result is then transformed into the standard numeric score in RSSTRESN and a character representation of the standard numeric score in RSSTRESC.

The table represents the items from the PASI V2 instrument.

4 SDTM Mapping Strategy

This section is used for reference regarding the CRF data capture and to understand the alignment of the instrument to the SDTM RS domain. It also provides guidance on how the result variables (RSORRES, RSSTRESC, and RSSTRESN) should be populated.

5 Supplemental Qualifier Name Codes

The following table contains additional standard name codes for use in the Supplement Qualifiers for Questionnaires (SUPPQS) special purpose dataset.

End of Document