MedMij FHIR Implementation Guide: PDF/A

MedMij:Vprepub/Issuebox FHIR IG

1 Introduction

MedMij specifies the format PDF/A for exchanging unstructured documents containing health information. Forum Standaardisatie is a Dutch governmental organization that aims to stimulate the use of open standards. PDF/A is one of the standards that is recommended by Forum Standaardisatie. More information regarding PDF/A can be found here: https://www.forumstandaardisatie.nl/standaard/pdf-nen-iso.

To achieve exchange of PDF/A files, MedMij adopts as much as possible from the Mobile access to Health Documents (MHD) profile from Integrating the Healthcare Enterprise (IHE) that defines a RESTful/HTTP interface to an XDS environment using HL7 FHIR STU3 resources. The MHD profile is written to be content agnostic and as such is suitable for much more than PDF/A. For this use case, we have limited the scope to PDF/A. The next section summarizes MHD and contains references to IHE MHD specification. The following sections provides an adaptation of the MHD profile to specify exchange of PDF/A documents in a MedMij context.

When implementing PDF/A, a minimum compliance must be assumed. That is, PDF/A-1 and PDF/A-b is also permitted within this. For more information, see the wiki page on this: https://en.wikipedia.org/wiki/PDF/A#Conformance_levels_and_versions

1.1 IHE MHD specification

Mobile access to Health Documents (MHD) profile defines a simple HTTP RESTful interface to an XDS like environment, based on HL7 FHIR. It describes four transactions:

1. submit submission sets, folders, new documents, and document metadata from the mobile device to a document receiver (Provide Document Bundle),
2. find submission sets matching query parameters (Find Document Manifest),
3. find document entries containing metadata based on query parameters (Find Document Reference),
4. retrieve a copy of a specific document (Retrieve Document).

These transactions leverage the document content and format agnostic metadata concepts from XDS but simplify them for access by constrained environments such as mobile devices, or other resource-constrained systems. The MHD profile does not replace XDS. It can be used to allow mobile devices, or other resource-constrained systems, access to an XDS health information exchange.[1]

Wiki: Mobile acces to Health Document (MHD)

Document: MHD Supplement (Rev 2.4 July 24, 2018)

Additional Supplement: Appendix Z on HL7 FHIR (Rev 1.2 July 21, 2017)

2 Actors and transactions involved

Table 1 shows the relevant actors, systems and FHIR capability statements in a MedMij context. The capability statements demonstrate the minimum requirements to be conformant to the full MHD specifications.

Persons		Systems		FHIR Capability Statements
Name	Description	Name	Description	Name	Description
Patient	The user of a personal healthcare environment.	PHR	Personal health record	Client@ http://nictiz.nl/fhir/CapabilityStatement/pdfa-clientcapabilities	PDFA FHIR Client requirements
Healthcare Provider	The user of a XIS	XIS	Healthcare information system	Server@ http://nictiz.nl/fhir/CapabilityStatement/pdfa-servercapabilities	PDFA FHIR Server requirements

Table 1. Actors, systems and FHIR capability statements

Table 2 shows the MHD actors and transactions in perspective of the systems used in a MedMij context.

Person	System	MHD Actors	MHD Transactions
Patient
	PHR
		Document Consumer	Find Document Manifests [ITI-66]
			Find Document References [ITI-67]
			Retrieve Document [ITI-68]
		Document Source	Provide Document Bundle [ITI-65]
Healthcare provider
	XIS
		Document Responder	Find Document Manifests [ITI-66]
			Find Document References [ITI-67]
			Retrieve Document [ITI-68]
		Document Recipient	Provide Document Bundle [ITI-65]

3 Use case: Find and retrieve existing PDF/A document(s)

3.1 Introduction

This section summarizes the IHE MHD profile to find and retrieve PDF/A documents in a MedMij context.

This FHIR implementation guide assumes that the PHR system is able to make a connection to the right XIS that contains the patient's information. It does not provide information on finding the right XIS nor does it provide information about security. Moreover, each transaction is performed in the context of a specific authenticated patient, for whose context (token) has been established using the authentication mechanisms described in the 'Afsprakenstelsel'. Each XIS Gateway is required to perform filtering based on the patient associated with the context for the request, so only the records associated with the authenticated patient are returned. For this reason, search parameters should not be included for patient identification.

3.2 Actors and transactions involved

Table 1 shows the relevant actors, systems and FHIR capability statements in a MedMij context. The capability statements demonstrate the minimum requirements to be conformant to the full MHD specifications.

Persons		Systems		FHIR Capability Statements
Name	Description	Name	Description	Name	Description
Patient	The user of a personal healthcare environment.	PHR	Personal health record	Client@ http://nictiz.nl/fhir/CapabilityStatement/pdfa-clientcapabilities	PDFA FHIR Client requirements
Healthcare Provider	The user of a XIS	XIS	Healthcare information system	Server@ http://nictiz.nl/fhir/CapabilityStatement/pdfa-servercapabilities	PDFA FHIR Server requirements

Table 1. Actors, systems and FHIR capability statements

Table 2 shows the MHD actors and transactions in perspective of the systems used in a MedMij context.

Person	System	MHD Actors	MHD Transactions
Patient
	PHR
		Document Consumer	Find Document Manifest
			Find Document Reference
			Retrieve Document
Healthcare provider
	XIS
		Document Responder	Find Document Manifest
			Find Document Reference
			Retrieve Document

Table 2. MHD actors and transactions in perspective of systems in a MedMij context

3.2.1 Transactions in scope

• Find Document Manifests – This transaction is used to issue parameterized queries that result in a list of Document Manifest resources.
• Find Document References – This transaction is used to issue parameterized queries that produce a list of Document Reference resources.
• Retrieve Document – This transaction is used to get documents.

Document Consumer shall implement at least one transaction: Find Document Manifests, Find Document References, or Retrieve Document. Document Responder shall implement all transactions.

3.2.2 Transactions out of scope

The MHD profile specifies how to send documents from a Document Source to a Document Receiver using the Provide Document Bundle transaction. However, sending PDF/A documents is currently out of scope for the MedMij context. The 'Afsprakenstelsel' first focuses on pulling data from a XIS to a PHR before considering push transactions. In the future, specifications of sending PDF/A documents from a PHR will be added.

3.3 Find and retrieve existing PDF/A document(s)

3.3.1 Find PDF/A or PDF/A collection

Discovery of PDF/A documents is done with the MHD defined transaction 'Find Document Reference' or 'Find Document Manifest.' The Find Document Reference retrieves FHIR DocumentReference Resources that represents a single reference to document per resource, for example, one PDF/A file. The Find Document Manifest retrieves FHIR DocumentManifest Resources. A DocumentManifest Resource gathers a set of DocumentReference Resources into a single package together with metadata that applies to the collection.

The Document Consumer requests DocumentReference or DocumentManifest Resources, matching a set of criteria, from the Document Responder. The Document Responder returns DocumentReference or DocumentManifest Resources that match the search criteria provided by the Document Consumer.

3.3.1.1 Request message

Search

The Document Consumer executes an HTTP GET conform to the FHIR RESTfull and search specification. A search query would have the following format.

GET [base]DocumentReference?[parameters]{&_format=[mime-type]}
GET [base]DocumentManifest?[parameters]{&_format=[mime-type]}

Example query to search for DocumentReferences of type Discharge summary with a current status.

GET http://example.org/fhir/DocumentReference?type=http://loinc.org|18842-5&status=current

Search Parameters The Document Consumer shall include search parameter status. The Document Consumer may supply, and the Document Responder shall be capable of processing, all query parameters listed below. These search parameters are a selection of the defined search parameters by the HL7 FHIR specification (search parameters: DocumentReference, DocumentManifest). See also the HL7 FHIR STU3 specification for searching.

DocumentReference			DocumentManifest
Name	Type	Description	Name	Type	Description
indexed	date	When this document reference was created	created	date	When this document manifest created
author (author.given and author.family)	string	Who and/or what authored the document	author (author.given and author.family)	string	Who and/or what authored the manifest
type	token	Kind of document (LOINC if possible)	type	token	Kind of document set
class	token	Categorization of document	source	uri	The source system/application/software
status	token	current / superseded	status	token	current / superseded
setting	token	Additional details about where the content was created (e.g. clinical specialty)
period	date	Time of service that is being documented
facility	token	Kind of facility where patient was seen
event	token	Main clinical acts documented
securitylabel	token	Document security-tags
format	token	Format/content rules for the document
related-id	token	Identifier of related objects or events

The PDF/A use cases within MedMij especially use of the search parameters indexed and status for DocumentReference and created and status for DocumentManifest.

3.3.1.2 Response message

The Document Responder shall process the query to discover the DocumentReference or DocumentManifest entries that match the search parameters given. The Document Responder returns an HTTP Status code appropriate to the processing as well as a Bundle including the matching DocumentReference or DocumentManifest Resources. When the Document Responder needs to report an error or warning, it shall use HTTP error response codes and should include a FHIR OperationOutcome with more details on the failure or warning. If the request message is processed successfully, whether or not any DocumentReference or DocumentManifest Resources are found, the HTTP status code shall be 200.

• The Document Responder shall place into the 'DocumentReference.content.attachment.url' element a full URL that can be used by the Document Consumer to retrieve the document using Retrieve Document transaction.
  • The Document Responder shall only include references which are resolved through the Document Responder to maintain control over the authentication and authorization. The Document Responder shall only serve DocumentReference or DocumentManifest resources that contain a reference which the Document Consumer may resolve.
• The Document Responder shall return only PDF/A documents and shall place into the 'DocumentReference.content.attachment.contentType' element the value 'application/pdf'.

Example of a response message

Example of a Bundle with 11 DocumentReference Resources. Only the first DocumentReference is displayed.

 
<Bundle xmlns="http://hl7.org/fhir">
    <id value="c0beb362-efc7-4cb9-b35a-c6cea0742156" />
    <meta>
        <versionId value="1498fcb4-af9c-404f-b445-e6634619df55" />
        <lastUpdated value="2017-10-25T11:25:00.336+00:00" />
    </meta>
    <type value="searchset" />
    <total value="11" />
    <link>
        <relation value="self" />
        <url value="http://vonk.furore.com/DocumentReference?status=current" />
    </link>
    <entry>
        <fullUrl value="http://vonk.furore.com/DocumentReference/c4f22730-bb5a-4f12-b4ef-c7bde0784426" />
        <resource>
            <DocumentReference xmlns="http://hl7.org/fhir">
                <id value="example-pdfa-documentreference2" />
                <meta>
                    <profile value="http://ihe.net/fhir/StructureDefinition/IHE.MHD.Query.Minimal.DocumentReference"/>
                </meta>
                <contained>
                    <Practitioner>
                        <id value="p1"/>
                        <name>
                            <family value="Kneder"/>
                            <given value="B.">
                                <extension url="http://hl7.org/fhir/StructureDefinition/iso21090-EN-qualifier">
                                    <valueCode value="IN"/>
                                </extension>
                            </given>
                        </name>
                    </Practitioner>
                </contained>
                <masterIdentifier>
                    <system value="urn:ietf:rfc:3986" />
                    <value value="urn:oid:1.2.276.0.7230010.3.1.2.1787205428.3024.1522314975.220899" />
                </masterIdentifier>
                <identifier>
                    <system value="http://example-xis.org/fhir/NamingSystem/DocumentReferenceID"/>
                    <value value="963369"/>
                </identifier>
                <status value="current" />
                <type>
                    <coding>
                        <system value="http://loinc.org/" />
                        <code value="34781-5" />
                        <display value="Infectious disease Consult note" />
                    </coding>
                </type>
                <class>
                    <coding>
                        <system value="http://loinc.org/" />
                        <code value="11488-4" />
                        <display value="Consult Note" />
                    </coding>         
                </class>
                <subject>
                    <reference value="Patient/example-pdfa-kwalificatie1" />
                </subject>
                <indexed value="2017-04-08T15:26:01+01:00" />
                <author>
                    <reference value="#p1" />
                </author>
                <description value="Infectious disease Consult note" />
                <securityLabel>
                    <coding>
                        <system value="http://hl7.org/fhir/v3/Confidentiality" />
                        <code value="V" />
                        <display value="very restricted" />
                    </coding>
                </securityLabel>
                <content>
                    <attachment>
                        <contentType value="application/pdf" />
                        <language value="en" />
                        <url value="http://example-test-server.org/fhir/Binary/example-pdfa-binary2" />
                        <title value="Example PDF - Infectious disease Consult note"/>
                    </attachment>
                </content>
            </DocumentReference>
        </resource>
        <search>
            <mode value="match" />
        </search>
    </entry>
    .......
    

3.3.2 Retrieve PDF/A document

After obtaining the location of the PDF/A document in the DocumentReference.content.attachment.url, the Document Consumer requests the document from the Document Responder. The Document Responder sequentially serves the PDF/A document to the Document Consumer. The context that was established in the initial request shall also apply when retrieving/serving the document contents.

3.3.2.1 Request Message

This message is an HTTP GET request to retrieve the document. See an example below.

GET http://example:9556/svc/fhir/Binary/1e404af3-077f-4bee-b7a6-a9be97e1ce32

The Document Consumer may provide an HTTP Accept header, according to the semantics of the HTTP protocols (see RFC2616, Section 14.1). The only MIME type assured to be returned is the MIME type indicated in the 'DocumentReference.content.attachment.contentType'. Within MedMij this is set to 'application/pdf'. The HTTP If-Unmodified-Since header shall not be included in the GET request

3.3.2.2 Response Message

The Document Responder shall process the request message. The Document Responder returns an HTTP Status code appropriate to the processing as well as the content of the requested PDF/A document in the HTTP message-body.

The document may be placed inside a FHIR Binary resource if it is useful to handle pure binary content using the same framework as other resources. Binary resources behave slightly differently from all other resources on the RESTful API. Specifically, when a read request is made for the binary resource that doesn't explicitly specify the FHIR content types "application/fhir+xml" or "application/fhir+json", then the content should be returned using the content type stated in the resource. e.g. if the content type in the resource is "application/pdf", then the content should be returned as a PDF directly.[2]

When the Document Responder needs to report an error or warning, it shall use HTTP error response codes and should include a OperationOutcome with more details on the failure or warning. If the Retrieve Document message is processed successfully the HTTP status code shall be 200.

Example of a response message

<Binary>
  <id value="1e404af3-077f-4bee-b7a6-a9be97e1ce32" />
  <meta>
    <versionId value="948f3653-c9a3-4831-bae5-f629319c194f" />
    <lastUpdated value="2017-09-20T17:55:14.098+00:00" />
  </meta>
  <contentType value="application/pdf" />
  <content value="JVBERi0xLjUNJeLjz9MNCjU1I........"/>   
</Binary>

3.4 Interactions, operations, search parameters

3.4.1 Interactions

The following logical interactions are needed for this use case:

• Search
• Read

3.4.2 Operations

There are no defined operations for this use case.

3.4.3 Search parameters

The following search parameter types need to be supported for this use case. No search result parameters need to be supported.

Search parameter types:

• token
• reference
• date
• uri

3.5 List of StructureDefinitions

IHE has defined StructureDefinitions and other Conformance resources applicable to this use case. The FHIR Implementation Guide on the IHE MHD wiki lists these StructureDefinitions.

Find and retrieve existing PDF/A document transaction uses the following StructureDefinitions:

• DocumentReference from Query with Minimal Metadata (canonical URL http://ihe.net/fhir/StructureDefinition/IHE.MHD.Query.Minimal.DocumentReference)
• DocumentManifest (canonical URL http://ihe.net/fhir/StructureDefinition/IHE.MHD.DocumentManifest)

• Optionally: DocumentReference from Query with Comprehensive Metadata (canonical URL: http://ihe.net/fhir/StructureDefinition/IHE.MHD.Query.Comprehensive.DocumentReference). This StructureDefinition has more mandatory field compared to Minimal Metadata and is used for XDS environments.

Next to the IHE MHD StructureDefinitions, MedMij uses the following HCIM StructureDefinitions for the response message.

Zib name NL	Zib name EN	FHIR Resource
Patient	Patient	Patient	http://fhir.nl/fhir/StructureDefinition/nl-core-patient
Zorgverlener	HealthProfessional	Practitioner	http://fhir.nl/fhir/StructureDefinition/nl-core-practitioner
Zorgaanbieder	HealthcareProvider	Organization	http://fhir.nl/fhir/StructureDefinition/nl-core-organization
-	-	DocumentManifest	http://ihe.net/fhir/StructureDefinition/IHE.MHD.DocumentManifest
-	-	DocumentReference	http://ihe.net/fhir/StructureDefinition/IHE.MHD.Query.Minimal.DocumentReference

Example instances of FHIR resources can be found on Simplifier. Please note: every effort has been made to ensure that the examples are correct and useful, but they are not a normative part of any information standard.

4 Use case: Send PDF/A document(s)

4.1 Introduction

This section summarizes the IHE MHD profile to Send PDF/A document(s) in a MedMij context.

This FHIR implementation guide assumes that the PHR system is able to make a connection to the right XIS that contains the patient's information. It does not provide information on finding the right XIS nor does it provide information about security. Moreover, each transaction is performed in the context of a specific authenticated patient, for whose context (token) has been established using the authentication mechanisms described in the 'Afsprakenstelsel'. Each XIS Gateway is required to perform filtering based on the patient associated with the context for the request, so only the records associated with the authenticated patient are returned. For this reason, search parameters should not be included for patient identification.

4.2 Actors

Person	System	MHD Actors	MHD Transactions
Patient	PHR	Document Source	Provide Document Bundle [ITI-65]
Healthcare provider	XIS	Document Recipient	Provide Document Bundle [ITI-65]

4.3 Send PDFA

4.3.1 PHR: Request message

When the patient (PHR) wants to send one or more PDF/A documents, it issues a send PDFA request message.

The PHR initiates a FHIR transaction using a create action by sending an HTTP POST request, composed of a FHIR Bundle resource containing one DocumentManifest resource, one or more DocumentReference resources, one or more Binary resources, one Patient resource, and zero or more Practitioner resources to the XIS recipient. References to the FHIR specification for the required transaction and POST requests are given in the interactions, operations and search parameters section below.

The PHR executes an HTTP POST against the XIS's base endpoint as shown below.

POST [base] {?_format=[mime-type]}

Read more:

• transaction
• create

The resources in the message SHALL be a valid instance of the listed StructureDefinitions below. All resources SHALL include their related profile canonical URL in the meta.profile element in order to show compliance.

4.3.1.1 Example - Bundle structure

<?xml version="1.0" encoding="UTF-8"?>
<Bundle xmlns="http://hl7.org/fhir">
    <type value="transaction"/>
    <entry>
        <fullUrl value="urn:uuid:96cf0274-9b2c-4bdc-b4c4-cb46f7a07097"/>
        <resource>
            <Patient xmlns="http://hl7.org/fhir">
                <!-- SNIP -->
            </Patient>
        </resource>
        <request>
            <method value="POST"/>
            <url value="Patient"/>
        </request>
    </entry>
    <entry>
        <fullUrl value="urn:uuid:278764fb-06b6-4f4f-8cef-4abaa3682111"/>
        <resource>
            <DocumentManifest xmlns="http://hl7.org/fhir">
                <!-- SNIP -->
            </DocumentManifest>
        </resource>
        <request>
            <method value="POST"/>
            <url value="DocumentManifest"/>
        </request>
    </entry>
    <entry>
        <fullUrl value="urn:uuid:2aa911db-9117-4e4b-97e4-d2f09dd28111"/>
        <resource>
            <DocumentReference xmlns="http://hl7.org/fhir">
                <!-- SNIP -->
            </DocumentReference>
        </resource>
        <request>
            <method value="POST"/>
            <url value="DocumentReference"/>
        </request>
    </entry>
    <entry>
        <fullUrl value="urn:uuid:6d035264-66ac-4df2-8bf8-d9a9bbf46111"/>
        <resource>
            <Binary xmlns="http://hl7.org/fhir" >
                <!-- SNIP -->
            </Binary>
        </resource>
        <request>
            <method value="POST"/>
            <url value="Binary"/>
        </request>
    </entry>
</Bundle>

4.3.2 XIS: Response message

The target XIS returns an HTTP Status code appropriate to the processing outcome and returns a Bundle, of type transaction-response, that contains one entry for each entry in the request, in the same order, with the outcome of processing the entry.

The target XIS SHALL return a Bundle with type set to transaction-response that contains one entry for each entry in the request, in the same order, with the outcome of processing the entry.

A client may use the returned Bundle to track the outcomes of processing the entry, and the identities assigned to the resources by the server. Each entry element SHALL contain a response element which details the outcome of processing the entry - the HTTP status code, and the location and ETag header values, which are used for identifying and versioning the resources. In addition, a resource may be included in the entry, as specified by the Prefer header.

4.3.2.1 Handling Errors

When the resource syntax or data is incorrect or invalid, and cannot be used to create a new resource, the server returns a 400 Bad Request HTTP status code. When the server rejects the content of the resource because of business rules, the server returns a 422 Unprocessable Entity error HTTP status code. In either case, the server SHOULD include a response body containing an OperationOutcome with detailed error messages describing the reason for the error, and perform a rollback of the creation of any previous entries.

Common HTTP Status codes returned on FHIR-related errors (in addition to normal HTTP errors related to security, header and content type negotiation issues):

• 400 Bad Request - resource could not be parsed or failed basic FHIR validation rules
• 404 Not Found - resource type not supported, or not a FHIR end-point
• 422 Unprocessable Entity - the proposed resource violated applicable FHIR profiles or server business rules. This should be accompanied by an OperationOutcome resource providing additional detail

Read more:

• create
• transaction

4.4 Interactions, operations, search parameters

4.4.1 Interactions

The following logical interactions are needed for this use case:

• create
• transaction

4.4.2 Operations

There are no defined operations for this use case.

4.4.3 Search parameters

No search parameters are needed for this use case.

4.5 List of StructureDefinitions

IHE has defined StructureDefinitions applicable to this use case. Although the IHE MHD Profile text (the published PDF) is Normative these conformance resources are labelled as Informative. Not all IHE MHD profiles are implementable as-is for the send use case because of errors that IHE does not intend to resolve in FHIR STU3, but instead, require updating to FHIR R4. MedMij is not ready upgrading to FHIR R4 for just this use case and has implemented the necessary fixes in the IHE FHIR STU3 profiles to support this use case. The IHE MHD profiles 'IHE.MHD.DocumentManifest' and 'IHE.MHD.ProvideDocumentBundle.Minimal' are therefore copied, adjusted for the known issues and released under Nictiz. The table below shows the IHE MHD profiles used for the Providing Document Bundle transaction and the relevant HCIM profiles.

Zib name NL	Zib name EN	FHIR Resource	URL profile
Patient	Patient	Patient	http://fhir.nl/fhir/StructureDefinition/nl-core-patient
Zorgverlener	HealthProfessional	Practitioner	http://fhir.nl/fhir/StructureDefinition/nl-core-practitioner
		PractitionerRole	http://fhir.nl/fhir/StructureDefinition/nl-core-practitionerrole
Zorgaanbieder	HealthcareProvider	Organization	http://fhir.nl/fhir/StructureDefinition/nl-core-organization
-	-	Bundle *	http://nictiz.nl/fhir/StructureDefinition/IHE.MHD.ProvideDocumentBundle.Minimal
-	-	DocumentManifest *	http://nictiz.nl/fhir/StructureDefinition/IHE.MHD.DocumentManifest
-	-	DocumentReference	http://nictiz.nl/fhir/StructureDefinition/IHE.MHD.Provide.Minimal.DocumentReference
-	-	List	http://nictiz.nl/fhir/StructureDefinition/IHE.MHD.List

'* Adjusted version of IHE MHD profiles by Nictiz.

Example instances of FHIR resources can be found on Simplifier. Please note: every effort has been made to ensure that the examples are correct and useful, but they are not a normative part of any information standard.

5 Release notes

Release notes can be found on the functional design page.