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© 2022 Clinical Data Interchange Standards Consortium, Inc. All rights reserved. 

1 Introduction

This document describes the CDISC implementation of the Acute Physiology and Chronic Health Evaluation II (APACHE II) instrument.

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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.

2 Copyright Status

CDISC believes this instrument to be in the public domain, but you should perform your own assessment. CDISC has included the APACHE II in the CDISC inventory 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.

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Knaus WA, Draper EA, Wagner DP, Zimmerman JE. APACHE II: a severity of disease classification system. Critical Care Medicine 1985; 13(10):818–29. 

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 APACHE II are listed below.

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1. The APACHE II provides weightings for 12 physiology measures, the sum of which yields a total acute physiology score (APS). This weighting system for 11 of the physiology measures is based on a numeric rating scale (0-4) where 0 reflects values within the normal range and an increase in the numeric rating scale represents an increase in the abnormality of the physiology measure in either the high or low direction.

   1. For example, the rating of 4 for heart rate (ventricular response) may coincide with multiple definitions depending on whether the abnormality is in the high or low direction (e.g., 4 = ">=180" or 4 = "<=39", respectively).

   2. Note that the score for the Glasgow Coma Score (GCS), the final physiology measure, is the reverse; lower scores indicate mild or no head injury and higher scores represent more severe head injury.

   3. Age and severe chronic health problems reflect diminished physiologic reserve; these have been directly incorporated into APACHE II. Chronological age is a well-documented risk factor for death from acute illness that is independent of severity of disease. This item includes a numeric rating (0, 2, 3, 5, 6) and a definition of what is represented by the rating (e.g., 6 = ">=75" years in age).

   4. Severe chronic organ system insufficiency or immunocompromised state markedly influenced outcome. Nonoperative and emergency surgery admissions had a substantially higher risk for death from prior chronic conditions than did elective surgical admissions. This indicates that patients with the most severe chronic conditions are not considered to be candidates for elective surgery. For patients with a history of severe organ system insufficiency or who are immunocompromised, a numeric rating of 2 or 5 is assigned for chronic health points, where 2 is assigned “for elective postoperative patients” and 5 is assigned “for nonoperative or emergency postoperative patients”.

   5. For the APACHE II, RSORRES is populated with the text description; the numeric rating is represented in the standardized character and numeric result variables RSSTRESC and RSSTRESN.

2. Records are created in rs.xpt (or in split rsap.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 = "PREFER NOT TO ANSWER"). If the reason is unknown, then RSSTAT = "NOT DONE" and RSREASND is missing.

3. Some items on the QRS APACHE II may be not done due to conditional branching per the instrument instructions. 

   1. The equation for computing the alveolar-arterial O₂ gradient is heavily dependent on inspired O₂ levels, so there are 2 methods for calculating oxygenation. When inspired O₂ levels ≥ 0.5 use the alveolar-arterial O₂ gradient and complete RSTESTCD = "APCH105A". When inspired O₂ levels < 0.5 use the partial pressure of oxygen (PaO₂) and complete RSTESTCD = "APCH105B". The other will be treated as not done due to conditional branching.

   2. In addition, arterial pH (RSTESTCD = "APCH106A") is preferred but in cases where oxygenation is normal and blood gases are not measured, serum HCO₃ (RSTESTCD = "APCH106B") can be substituted. Only 1 of these 2 physiological parameters will be measured and the other will be treated as not done due to conditional branching. 

   3. In addition, a chronic health response, item RSTESTCD = "APCH115", is only assigned (along with the points) when the patient has a history of severe organ system insufficiency or is immunocompromised. Otherwise it will be not done due to conditional branching.

   4. A record is created in rs.xpt for all items. When an item is considered conditionally branched, it is represented as follows:

      1. RSSTAT = "NOT DONE"       

      2. RSDRVFL = "Y" (the record is derived as a "NOT DONE" record)
         

      3. QNAM = “RSCBRFL”, QLABEL = “Conditional Branched Item Indicator “, QVAL = “Y” (RS supplemental qualifier variable)

      4. RSORRES, RSSTRESC, and RSSTRESN are set to null (missing)

4. The APACHE II instrument includes a total APS and total APACHE II score which are considered as captured data on the CRF and 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 on the CRF. If scores are received by the sponsor,

   1. It is recommended that they are submitted to SDTM and verified in ADaM.

5. Terminology

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

   2. A full list of value sets for the result and unit fields are provided in Section 4, SDTM Mapping Strategy. 

3.2 Example for the QRS APACHE II RS Domain Model

The rsap.xpt dataset represents the items from the APACHE II. The RS domain was split into 2 physically separate datasets: the APACHE II instrument (rsap.xpt) and the GCS (rsgc.xpt). Each dataset represents a subset of the RS domain. Note: In this example, the vital sign and lab values used to answer the APACHE II items were also collected and represented separately in the VS and LB domains. RSLNKID is used to link the APACHE II records to their corresponding findings in their respective source domains. This relationship is defined in the RELREC table.

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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, RSSTRESN, and RSORRESU) should be populated.

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