Revision History

© 2022 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 Fredriksson (PASI FREDRIKSSON) instrument. Note that Version 1 of the CDISC Controlled Terminology is scheduled for deprecation and an associated CDISC Version 1 instrument and SDTMIG QRS supplement were never released.

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 published articles describing the instrument as well as input from PASI instrument 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 Questionnaires, 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 FREDRIKSSON 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 FREDRIKSSON:

• Fredriksson T, Pettersson U. Severe Psoriasis - Oral Therapy with a New Retinoid. Dermatologica. 1978; 157(4):238-244.
• CDISC believes this instrument to be in the public domain, but you should perform your own assessment.

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 FREDRIKSSON are listed below.

The PASI FREDRIKSSON is a tool used to assess the severity of psoriasis. However, there is no standard set of responses for the PASI that is used throughout industry. This supplement uses the Fredriksson article as the stand for responses with some slight modifications from SME input. The PASI FREDRIKSSON divides the body into 4 sections (i.e., head, trunk, upper extremities, lower extremities) 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 include a numeric rating (0-4) and a definition of what is represented by the rating (e.g., 0 = "None"). Instead of "striking" and "exceptionally striking" that are referenced in the Fredriksson article, "severe" and "very severe" were used due to SME input suggesting these responses are used more frequently. For the PASI FREDRIKSSON, RSORRES is populated with the text description; the numeric rating is represented in the standardized character and numeric result variables RSSTRESC and RSSTRESN.

   1. CDISC created a CRF based on the Fredriksson article using the symptom terms "erythema/redness", "thickness/induration", and "desquamation/scaling". Per subject-matter expert recommendations, desquamation was included with scaling even though desquamation is not referenced in the Fredriksson article.
      
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; the numeric rating is represented in the standardized character and numeric result variables RSSTRESC and RSSTRESN.
   

3. The PASI FREDRIKSSON 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 Fredriksson 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.

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, that reason is represented in RSREASND (e.g., RSREASND = "REFUSED"). If the reason is unknown, 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 FREDRIKSSON RS Domain Model

The PASI FREDRIKSSON example below shows the terminology used to implement the instrument in the RS domain. The example uses CDISC Controlled Terminology for RSTESTCD, RSTEST, and RSCAT. All original results, matching the CRF item response text, are represented in RSORRES. This result is then represented as a standard numeric score in RSSTRESN and as a standard character representation in RSSTRESC.

The table represents the items from the PASI FREDRIKSSON 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.

RSTESTCD = "PASI0301" RSTEST = "PASI03-Head: Erythema/Redness"

RSTESTCD = "PASI0302" RSTEST = "PASI03-Head: Thickness/Induration"

RSTESTCD = "PASI0303" RSTEST = "PASI03-Head: Desquamation/Scaling"

RSTESTCD = "PASI0305" RSTEST = "PASI03-Up Extrem: Erythema/Redness"

RSTESTCD = "PASI0306" RSTEST = "PASI03-Up Extrem: Thickness/Induration"

RSTESTCD = "PASI0307" RSTEST = "PASI03-Up Extrem: Desquamation/Scaling"

RSTESTCD = "PASI0309" RSTEST = "PASI03-Trunk: Erythema/Redness"

RSTESTCD = "PASI0310" RSTEST = "PASI03-Trunk: Thickness/Induration"

RSTESTCD = "PASI0311" RSTEST = "PASI03-Trunk: Desquamation/Scaling"

RSTESTCD = "PASI0313" RSTEST = "PASI03-Low Extrem: Erythema/Redness"

RSTESTCD = "PASI0314" RSTEST = "PASI03-Low Extrem: Thickness/Induration"

RSTESTCD = "PASI0315" RSTEST = "PASI03-Low Extrem: Desquamation/Scaling"

RSTESTCD = "PASI0304" RSTEST = "PASI03-Head: Area Score"

RSTESTCD = "PASI0308" RSTEST = "PASI03-Up Extrem: Area Score"

RSTESTCD = "PASI0312" RSTEST = "PASI03-Trunk: Area Score"

RSTESTCD = "PASI0316" RSTEST = "PASI03-Low Extrem: Area Score"

End of Document