SDOH Clinical Care
1.0.0 - STU 1

SDOH Clinical Care, published by HL7 International - Patient Care WG. This is not an authorized publication; it is the continuous build for version 1.0.0). This version is based on the current content of and changes regularly. See the Directory of published versions

Checking Task Status

Checking Task Status

The Gravity workflow around referrals involves all parties involved being aware of when relevant Tasks and associated ServiceRequests have been created and/or updated. In most cases, the Tasks will reside within the EHR system of the initiating practitioner. In this case, the EHR will always be aware when the Task is updated, so the challenge of monitoring Tasks will fall solely on the service delivery organization. However, the Gravity workflow also supports Tasks being posted to an intermediary organization that is responsible for managing the referral fulfillment process. In these circumstances, both EHR and service delivery organizations will need to monitor for changes to Tasks.

The specific types of events to be monitored for include: Service Delivery Organizations

  • A new Task has been assigned to the organization
  • A new Task that is unassigned - but which is seeking action within the organization’s purview has been created
  • A ServiceRequest associated with a Task assigned to the organization has been modified
  • A ServiceRequest associated with a Task assigned to the organization has been cancelled

EHR systems

  • An assigned Task has been accepted or rejected
  • An unassigned Task has now been assigned
  • Outputs have been added to a Task
  • A Task has been marked as complete

There are two mechanisms for detecting the above changes - polling and subscriptions.


In this mode, the system needing information (the ‘client’) occasionally queries the system maintaining the relevant Tasks and/or ServiceRequests to see if there is anything ‘new’. Clients may need to perform queries against multiple clients if not all relevant Tasks and ServiceRequests will be maintained on the same server. To poll, the client will perform a search for Tasks that are filtered to those either owned by or requested by the searching organization. The search would also filter to only include those Tasks that had been created or changed since the server last looked. E.g.

[base]/Task?owner=Organization/123&_lastupdated=gt2021-05-03T17:23:18.1732-04:00 or [base]/Task?owner=Organization/456&_lastupdated=gt2021-05-03T17:23:18.1732-04:00

The time-stamp specified would be the search result returned from the last search.

OPEN ISSUE: Are the organizations in question going to have RESTful ids on the server that holds the tasks or do we need to change this to: [base]/Task?owner:identifier=http%3A%2F%2Fsomeorganization%2Fsome%2Fidentifier%2Fsystem|123&_lastupdated=2021-05-03T17:23:18.1732-04:00

If unassigned Tasks are possible - i.e. where the organization to perform the service isn’t pre-identified and is open to whoever wishes to claim the Task and perform it - organizations interested in examining Tasks available to claim would poll as follows:


The frequency of polling needs to be often enough to allow for timely response to changes, while not imposing too high a requirement on system performance. For Gravity, systems that use polling SHALL check for new/updated information at least once per business day and SHOULD check for information at least once per hour during normal hours of operation. Systems SHOULD NOT query more often than every 15 minutes unless there is an urgent change they are monitoring for.


In the subscription mechanism, instead of the client system regularly querying the server to see if there are new Tasks or changes to existing Tasks, the client creates a Subscription instance on the server that indicates that it wants to be notified about changes to Tasks and, in the Subscription, provides filters that describe what subset of Tasks it is interested in. The server will then push notifications when there are new Tasks and the client can then query for the specific Tasks that have changed.

This Gravity functionality is based on the R4 Subscription backport implementation guide. This implementation guide allows pre-adoption of the FHIR R5 topic-based subscription approach in R4 implementations and is the subscription approach that most U.S. EHR vendors have agreed to support. Implementers of this Gravity IG who choose to support Subscription must comply with the Subscription Backport IG for the purpose of monitoring Tasks and, if necessary, ServiceRequests.

For the purposes of this IG, there will be no need for ‘topic discovery’ as there are only two topics of interest - one for monitoring Task and one for monitoring ServiceRequest. While neither of these topics are unique to the Gravity IG, because no standard topics have yet been defined for US Core, this IG will define the needed topics here. In the future, these topics may be subsumed into general-purpose topics defined by US Core and/or the FHIR core specification.

Systems supporting subscription SHALL support the rest-hook channel mechanism, though they may choose to support other channel approaches. Servers SHALL support both JSON and XML and clients SHALL support at least one of these. Client and server SHALL support id-only, though they may also support other content approaches. The id-only approach means that the id of the Task or ServiceRequest that was updated or created will be provided. The client will then perform a read or a query to retrieve the specified record(s) specified in the subscription notification. E.g.


If search is used, the client MAY use _include=Task:focus to retrieve the referenced ServiceRequest as well. E.g. [base]/Task?_id=1234m5678&_include=Task:focus

Task topic

This topic allows for monitoring for newly created tasks as well as updates to assigned or requested tasks.

Property Value Notes
URL This is what will appear in backport-topic-canonical extension
resourceTrigger.resourceType Task
resourceTrigger.methodCriteria create, update, delete 'delete' is not an expected action within the scope of this IG
resourceTrigger.queryCriteria create, update, delete 'delete' is not an expected action within the scope of this IG
resourceTrigger.queryCriteria.current status:not=draft&intent=order
resourceTrigger.queryCriteria.current status:not=draft&intent=order
resourceTrigger.queryCriteria.resultForDelete test-passes
resourceTrigger.canFilterBy _lastUpdated
owner or requester will almost always be used. code and status can be used to further filter if desired
ServiceRequest topic

This topic allows for monitoring for changes to a ServiceRequest when an organization is involved in fulfilling that request. (E.g. to be aware if the request is suspended, cancelled or otherwise modified. The intent with this subscription is that the filter criteria will be updated regularly to refer to the specific ServiceRequest ids the organization is fulfilling. Once fulfillment is complete, the ServiceRequest will no longer need to be monitored.

Property Value Notes
URL This is what will appear in backport-topic-canonical extension
resourceTrigger.resourceType ServiceRequest
resourceTrigger.methodCriteria update, delete 'delete' is not an expected action within the scope of this IG
resourceTrigger.canFilterBy _lastUpdated