The section on handling pending authorization responses offers two methods, a polling option wrapping the 278I and a subscription option that tells the EHR when to poll. This has a couple issues:

• The content of the 278I and 278R is different such that if a payer needs additional documents, that information isn't supported in 278I so you wouldn't see it during polling (more info in https://jira.hl7.org/browse/FHIR-36114)
• Polling and subscriptions to poll incur more network traffic and opportunities for failure than just supporting a push

To address those issues we should support the equivalent of an async 278R push, so our data model stays consistent regardless of initial vs subsequent communication, and so that updates are sent in a timely manner with the minimum number of transactions. A couple options for this:

• Define a $update-claim-response operation that EHRs would support and payers would call after updating their claim response
• Maybe you could just have the payer call ClaimResponse.Update on the EHR system, however I'm not sure how they would actually have the correct EHR FHIR ID so this approach might not be possible.