CDA Documents and XSL Transforms

This chapter provides an introduction to the way InterSystems products handle CDA documents, beginning with an overview of the structure of a CDA document, then describing the library of XSLTs (XSL transformations) that turns CDA documents into SDA, and vice versa.

CDA Document Structure

The root node of all CDA documents is <ClinicalDocument>. Beneath it are three logical divisions: a header, one or more Sections, and one or more Entries within each Section.

The header contains metadata, patient demographics, and provider information.
A Section establishes a broad concept, such as Allergies or Medication. A Section may contain unstructured, “narrative” data in addition to structured data in the form of Entries.
An Entry is embedded within a Section and represents an individual instance within the larger concept. For example, one Entry in the Allergies section might represent a peanut allergy, and another a pollen allergy.

When a CDA document is transformed, Sections and Entries receive transformation instructions from support files, which are discussed in the section “XSLT Directory Structure for CDA Documents”.

All portions of a CDA document conform to templates, which are defined by IHE or some other organization. These templates are identified by OIDs (object identifiers). Templates provide structured, reusable formats for clinical data in a CDA document, and they also indicate the specifications with which a CDA document must comply. Templates can inherit from one another, imposing further constraints. OIDs are made up of strings of integers separated by periods, such as 2.16.840.1.113883.3.88.11.83.102. For more information about a specific template, enter its OID into an Internet search engine; there are many online resources that provide detailed OID specifications.

Each Section contains structured and unstructured data. Unstructured data contains items such as text, numbers, and even entire paragraphs; these are located in the narrative portion of a Section. Unstructured data accomplishes two tasks. First, it provides the human-readable section of the CDA required by CDA specifications. Second, unstructured data provides a reference point to which subsequent structured data may refer.

Structured data appears within Sections as Entries. As the name suggests, structured data has more specifications to which it must adhere. Each Entry has one or more templates associated with it, indicating the standards to which that Entry conforms. Entries contain a variety of data, including dates, intervals, strings, and OIDs. Additionally, they contain coded data, and particular fields may expect certain input patterns. A codeSystem attribute, for example, must be a valid OID and cannot be blank.

The following table describes the CCDA v2.1 Sections supported by InterSystems. The left column displays XSLs, while the right column displays their corresponding section names.

XSL	CCDA Section	Notes
AdvanceDirectives.xsl	Advance Directives
AllergiesAndOtherAdverseReactions.xsl	Allergies and Intolerances
AssessmentAndPlan.xsl	Assessment and Plan
Assessments.xsl	Assessment
ChieftComplaint.xsl	Chief Complaint	Supported for export only.
ChiefComplaintAndReasonForVisit.xsl	Chief Complaint and Reason for Visit	Supported for export only.
CarePlan.xsl		This XSL defines SDA elements for: Care Plan Type Care Plan Provider Care Plan Support Contacts Care Plan SetId Care Plan Version Care Plan Authors Care Plan Organizations Care Plan Health Concern IDs Care Plan Goal IDs
DiagnosticResults.xsl	Results
DischargeDiagnosis.xsl	Discharge Diagnosis
EncounterDiagnoses.xsl		Used to supplement the default Encounter section specification.
FamilyHistory.xsl	Family History
FunctionalStatus.xsl	Functional Status
Goals.xsl	Goals
HealthConcerns.xsl	Health Concerns
HistoryOfPastIllness.xsl	History of Past Illness
HistoryOfPresentIllness.xsl	History of Present Illness
HospitalAdmissionDiagnosis.xsl	Admission Diagnosis
HospitalCourse.xsl	Hospital Course	Supported for export only.
HospitalDischargeInstructions.xsl	Hospital Discharge Instructions
HospitalDischargeMedications.xsl	Discharge Medications
Immunizations.xsl	Immunizations
Instructions.xsl	Instructions
Interventions.xsl	Interventions
Medications.xsl	Medications
MedicationsAdministered.xsl	Medications Administered
Non-RatifiedSections.xsl		This XSL defines an SDA element for Care Considerations, including the following sub-fields: Entered By Entered At Entered On External ID Document Time Document Number Document Name Document Type File Type Document Stream Document Status Clinician Custom SDA Data
Outcomes.xsl	Health Status Evaluations and Outcomes
Payers.xsl	Payers
PhysicalExams.xsl	Physical Exam	Supported for export only.
PlanOfTreatment.xsl	Plan of Treatment
ProblemList.xsl	Problem
ProceduresAndInterventions.xsl	Procedures
ReasonForReferral.xsl	Reason for Referral	Supported for export only.
ReasonForVisit.xsl	Reason for Visit
SocialHistory.xsl	Social History
VitalSigns.xsl	Vital Signs

XSLT Directory Structure for CDA Documents

InterSystems healthcare products ship with a library of XSLTs to transform CDA documents into SDA, and vice versa.

To view the available root-level XSLTs, navigate to your installation directory and follow the path install-dir\CSP\xslt\SDA3. This directory contains the XSLTs, many of which are named for the actions they perform.

For example, CCDA-to-SDA transforms Consolidated CDA 1.1 CCD into SDA, CCDAv21-to-SDA transforms Consolidated CDA 2.1 CCD into SDA, SDA-to-C32v25 transforms SDA into C32, and so on. These files in turn make calls to other files located in the CDA-Support-Files directory, located at install-dir\CSP\xslt\SDA3\CDA-Support-Files.

Each root-level XSLT (for example, CDA-to-SDA.xsl) begins with xsl:include declarations to pull in the appropriate files located in the CDA-Support-Files directory.

This section describes the various directories within CDA-Support-Files and the functions they serve. As the image indicates, CDA-Support-Files contains the directories:

System — Source-controlled, non-configurable files defining widely used items such as OIDs and templates.
Site — Configurable files that are used by various XSLTs.
Import and Export — Files that are called when transforming CDA into SDA, and vice versa.
Reports — Mostly transformations that turn CDA documents into HTML so that they can be displayed in a web browser. This directory is not described below.

Important:

XSLTs are cached, so you must restart the production in the applicable namespace after editing a transformation for the changes to take effect.

The System Directory

The System directory contains static files that define a wide range of items. Items in this folder are not configurable.

The directories within System are:

Common — Utility templates that are not widely used.
OIDs — Variables associated with the OIDs
Site-Defaults — A source-controlled version of the Site directory. This directory is not called at runtime. For more information, see “The Site Directory” section.
Templates — Variables associated with the template identifiers

The Site Directory

The Site directory contains files that can be uniquely configured.

Important:

The files in this directory are not touched upon upgrade in order to preserve customizations. After upgrading, you must manually reconcile these files with the new versions of the files in install-dir\CSP\xslt\SDA3\CDA-Support-Files\System\Site-Defaults, regardless of whether they have been customized. Any files that you did not customize in the Site directory must also be refreshed with the new version in Site-Defaults by manually copying the files into the directory.

The files within Site are:

ImportProfile and ExportProfile — Configuration settings that are used during the process of importing and exporting a CDA document into and from your instance. See the “Import Profile” and “Export Profile” sections below.
OutputEncoding — An XSLT used on export to control the encoding of the resulting CDA document. The default is UTF-8.
Variables — Configurable variables used during import or export. These variables represent organizations and set up “home” information.

Import Profile

The import profile controls configuration settings when importing a CDA document. Almost every variable in the import profile has a <sectionTemplateId>, an <entryTemplateId>, or both; the exception is resultsImportConfiguration, which instead has separate template IDs for <sectionC32TemplateId> and <sectionC37TemplateId>. The presence of a <sectionTemplateId> or an <entryTemplateId> depends on whether the variable in question is found in a section module or an entry module.

Additionally, some variables may contain other settings. The following table lists those settings as well as the variables to which they belong and their values.

Import Profile Settings

Variable Name	Setting	Value
generalImportConfiguration/blockImportCTDCodeFromText	disabled	Blocks the import of a CDA string, narrative text, or originalText into an SDA CodeTableDetail Code property when the CDA @code attribute is not available. If this setting is activated and the coded element is nullFlavor, no text is loaded into the SDA Code Property unless the target SDA element is OrderItem and the orderItemDefaultCode or orderItemDefaultDescription configuration parameter is turned on. If blockImportCTDCodeFromText is not enabled, the import behavior remains unchanged from the previous version.
generalImportConfiguration/sdaActionCodes	enabled	Indicates whether or not SDA action codes are enabled. SDA action codes control the update and deletion of data.
generalImportConfiguration/sdaActionCodes	overrideExternalId	Indicates whether CDA <id> elements should be used to import SDA ExternalId property values where applicable.
generalImportConfiguration	enableOtherOrders	When enabled, and a CDA Result cannot be classified as an SDA LabOrder or RadOrder, then the Result is imported as an SDA OtherOrder. Otherwise the Result is not imported.
generalImportConfiguration/representedOrganizationId	concatRootAndNumericExtension	When the value equals 1, if hl7:representedOrganization/hl7:id @root is an OID and @extension is numeric, then both are concatenated into one facility OID.
generalImportConfiguration	narrativeImportMode	A value of 1 imports the narrative section as text, importing both <br/> and narrative line feeds as line feeds. A value of 2 imports as text, using only <br/> as a line feed. This applies only to the import of Result Text, Hospital Discharge Instructions, and Reason for Visit.
dischargeMedicationsImportConfiguration medicationsImportConfiguration medicationsAdministeredImportConfiguration	pharmacyStatus	Indicates the status of a medication. Its value depends on the variable in which it is located, which in turn indicates the CDA section from which the medication is being imported.
planImportConfiguration	effectiveTimeCenter	When set to 0: effectiveTime/center values will be imported to FromTime. When set to 1 :effectiveTime/center values will be imported to FromTime and ToTime. Note: If effectiveTime/center is populated for a particular care plan, effectiveTime/high and effectiveTime/low should not be populated for that care plan.
resultsImportConfiguration	resultOrganizerTemplateId	Helps to select the correct hl7:organizer within a given results entry when there is more than one. One alternate value it might be given is $ihe-PCC-LabBatteryOrganizer.
resultsImportConfiguration	orderItemDefaultCode	Code to use for SDA OrderItem Code when a CDA Result does not include information from which to derive an OrderItem Code or Description.
resultsImportConfiguration	orderItemDefaultDescription	Description to use for SDA OrderItem Code when a CDA Result does not include information from which to derive SDA OrderItem Code or Description.
healthFundImportMode	enabled	A value of 1 means that this setting is enabled. This is the default. The system adds a Health Fund streamlet for each Encounter to the resulting SDA.
healthFundImportMode	disabled	A value of 0 means that this setting is disabled. The system will not create a Health Fund streamlet for every Encounter.
memberEnrollmentImportMode	enabled	A value of 1 means that this setting is enabled. For each Payor received in the CCD/CCDA, the system will create a Member Enrollment streamlet in the resulting SDA.
memberEnrollmentImportMode	disabled	A value of 0 means that this setting is disabled. This is the default. The system will not create a Member Enrollment streamlet in the resulting SDA.

Export Profile

Most elements in the export profile have an <emptySection> element, a <narrativeLinkPrefixes> element, or both. <emptySection> elements control whether or not to export a section that contains no information. <narrativeLinkPrefixes> allow you to enter text to be included in the narrative, or human-readable, portion of a CDA document.

Additionally, some sections may contain other settings. These settings can be edited and augmented depending on the data that is to be exported. The following table lists those unique settings as well as the sections in which they are found and their values.

Export Profile Settings

Section	Setting	Value
admissionDiagnoses/diagnosisType	codes	Codes that can be used as additional diagnosis types for admission.
advanceDirectives/advanceDirectiveType	codes	Codes that correspond to various advance directive types, such as resuscitation or intubation.
assessment/diagnosisType	codes	Codes that can be used as additional diagnosis types for assessment.
dischargeDiagnoses/diagnosisType	codes	Codes that can be used as additional diagnosis types for discharge.
encounterDiagnoses/exportToC32	disabled	If enabled (value = 1), allows the export of encounter diagnoses to CDA C32.
medications/currentMedication	includeHistoricalMedications	Controls whether or not to include historical medications in the current medications list.
medications/currentMedication	windowInDays	Limits how old in days a medication can be and still be included in the current medications list.
medications/currentMedication	hideNarrativeColumn	Hides the narrative column.
planOfCare	effectiveTimeCenter	When set to 0: FromTime will be exported to effectiveTime/low and ToTime will be exported to effectiveTime/high. When set to 1: IF FromTime and ToTime have the same non-null value, that value is exported to effectiveTime/center. ELSE: if FromTime has a value, it is exported to effectiveTime/low. If ToTime has a value it is exported to effectiveTime/high. EXCEPTION: if ProcedureTime has a value, it is exported to effectiveTime/Center in place of FromTime.
problems/currentCondition	codes	Codes that correspond to various problem types, such as ACTIVE or CHRONIC.
problems/currentCondition	windowInDays	Limits how old in days a medication can be and still be included in the current problems list.
socialHistory/emptySmokingStatus	exportData	Indicates whether or not to export smokingStatus when it contains no data.

The Import and Export Directories

The Import and Export directories contain files that are called when XSLTs transform data.

The Import directory contains those files that are called when transforming CDA into SDA.
The Export directory contains those files that are called when transforming SDA into CDA.

Both the Import and the Export directories contain subdirectories labeled Common, Entry-Modules, and Section-Modules.

The Common directory contains XSLTs that set up commonly used global variables for the various transformations and provide templates that contain commonly used logic, such as address-Home.
The Section-Modules directory contains XSLTs that transform data to or from a given CDA section; the name of each XSLT corresponds closely to the name of the CDA section it transforms.
The Entry-Modules directory contains XSLTs that map the transformation into the correct Entry of a document and then parse the coded data. As a result, XSLTs within this directory tend to be significantly longer than their counterparts in the Section-Modules directory.

Each root-level XSLT (for example, CDA-to-SDA.xsl) begins with xsl:include declarations to pull in the appropriate Section-Modules, Entry-Modules, and Common files, as well as other necessary files.

Customizing CDA XSL Transformations