In a recent letter to the HITSP panel describing the interoperability needed for meaningful use, I discussed point to point interoperability and persistent document exchange. Here are a few additional details about these approaches.
Point to point does not imply that one EHR is communicating with one recipient via a specialized interface for that interaction. Requiring a custom interface for every connection between two stakeholders would not be scalable. Point to point simply implies that a transient message is sent from a data source such as a cloud computing EHR hosting center to a data recipient such as an e-prescribing gateway, a healthcare information exchange, or payer.
In Massachusetts we use interface engines, gateways such as NEHEN, and community-based health information exchanges such as EHX created by eClinicalWorks to connect thousands of users in dozens of organizations via transient messages.
There has been debate in the informatics community about using point to point messaging as a means of interoperability. Some suggest that all EHRs should have consistent data elements to foster the most complete interoperability. Although a common information model will be helpful in the future, we need to implement "good enough" standards now to improve quality and efficiency in the short term.
Sending packages of content between organizations using a common web-based transport mechanism enables such high value data exchanges such as e-prescribing, lab data sharing, and administrative workflow.
Point to point interoperability works very well for secure transmission of a content package between two stakeholders. To ensure that HITSP interoperability specifications using point to point approaches are sufficiently complete to test, we need to be very specific about the transport mechanism, as complete as possible listing the vocabularies/code sets, and as constrained as possible describing the package contents. ONC will soon release a Common Data Transport Extension/Gap document which illustrates the kinds of secure transport transactions we'll need to harmonize.
What are the disadvantages of the point to point approach?
a. It does not work for complex scenarios such as an Emergency Department requesting the lifetime clinical record of a person from all the places their data exists in the country. That requires a master patient index, a record locator service, or a national healthcare identifier. In the short term, there are enough high value provider to pharmacy, provider to provider, and provider to payer exchanges that waiting to solve the unique patient identifier problem is not necessary.
b. Auditing the transfer of clinical records between two organizations based on transient messages may be more challenging than exchanging persistent documents with a non-reputiable time/date stamp and signature.
c. Reconstructing a damaged clinical record by replaying transient messages from an interface engine may be harder than simply reassembling persistent documents.