Monday, September 04, 2006

HL7 RIM: Still an Incoherent Standard ?

The paper
was presented at the Medical Informatics Europe conference in Maastricht on August 28. The powerpoint slides from the presentation are available here.

Gratifyingly, Gunther Schadow's talk at the conference embraced the view that the RIM should henceforth be a standard based on realist ontology. Thus biomolecules, he argued, should be treated not as Acts of observation (as is done currently by HL7's Clinical Genomics WG), but rather as Entities. We are hoping that the two conflicting views of biomolecules and similar items in RIM-based artifacts will now be reconciled in these terms, so that biomolecules (etc.) will henceforth always be classified under Entity, while acts of observation of biomolecules will be classified, straightforwardly, as Acts of observation.

We are hoping, in the same spirit, that the RIM will now add a new superclass of the Act class, which I propose should be called 'Event'. 'Act' could then henceforth be applied only to those Events which are intentional actions. This new superclass could be applied for example to snakebites, floods, fires, processes of infection, and other items hitherto problematic for the RIM. HL7 could then use Event, for the snakebite event, and Act of observation for: Act of observation of the snakebite event.

We are hoping, finally, that the new more realistic RIM will add a new, class called Dependent Continuant (for those continuant items which are not Entities because they are not made of physical parts). This would allow a coherent treatment of diseases, which could be classified by the RIM as Dependent Continuants, leaving observations of disease to be classified, again, under: Act of observation. The new class of Dependent Continuant could then include not only diseases but also qualities such as temperature, blood pressure, etc.

Adding the two new classes of Event and Dependent Continuant would thereby bring the RIM still closer to a realist ontology, and thereby yield a great boost in coherence. For reasons stated briefly in part 2 of this, and at greater length here, it would also add to the RIM's ability to support logical reasoning -- since items in reality would no longer be confused with observations.

Postscript (July 16, 2008)

I still see no evidence that the small proposed changes described in the above have even been considered by the wider HL7 community, in spite of the recognition by Gunther Schadow of the benefits that they would bring. On the other hand, further evidence of the problems created by the existing dual framework continues to accumulate. Is the RIM a representation of healthcare information or a representation of the healthcare entities about which such information is collected? From one side HL7' s answer to this question seems to be (in my view, absurdly): there is no difference. From another side, there is confusion and consternation, as illustrated by the following exchange:

From: Koisch, John [USA]
Sent: Wednesday, July 09, 2008 1:17 PM
To: arb
Subject: FW: Entity states and Roles


An issue has emerged in the context of the NCI specification of a Person Service (a specification that the ArB is planning on using as an example of the type of specifications that would be produced as ballotable specifications). In the current RIM world view, the creation of Entity instances is fundamentally linked to instances of Registration Acts and refers only to the actual thing rather than an electronic representation of that thing. From a RIM perspective, this means that Entities essentially only exist in the context of Roles and ultimately in Acts The issue emerges when one considers the Entity state diagram and what it means in the context of a Registration Act, i.e. how the semantics of the Entity instances life cycle and the Registration Acts process semantics are partitioned across RIM structures vs the partitioning of the same semantics in a services world.

Please feel free to simply comment on the above statement. However, for context and in the desire to express things completely, there are some attachments. I have included two alternate state diagrams that Charlie and I proposed in the longish email thread between Charlie, Lloyd, Grahame, and myself. And apologies in advance for the lack of presentation of those threads ... there were too many to include and it is difficult to really pull them apart. However, a rough representation of the issues are below

Issue #1

Proposition a - There is _at least_ support for having an electronic record that is created but not in the active state

Proposition b - It is likely that there is actually a "pending" state in addition to the inactive and active states that are defined.

Reply - There is a big difference between a person's record (business conception) and the RIM.Person. RIM Persons (and other RIM.entities) essentially only ever exist in the "Active" state or the "Nullified" state.

Conclusion - there seems to be a fundamental disconnect between RIM.Entity, its states, and the way most IT people see entity. The disjoin is exacerbated by the RIM.Entity state machine that does not seem to refer to real entities (it does refer to their representations), even though the RIM uses RIM.Entity only as it pertains to real people. Lloyd maintains that the RIM.Entity cannot, in fact, contain any metadata about the person.

Issue #2

Proposition a - Entities need to be able to express their own state.

Proposition b - Entities need to be able to have states separate from the modeled RIM.Acts in which they are contained.

Reply - Lloyd maintains that RIM.Entity State is trivial (either null or active) and that at any rate, it is only valid to speak of entities in the context of an Act, say, a registration Act.

Rejoinder - But this is a fundamentally different notion than that maintained by most, if not all, of the IT community. And this does not translate to an architecture where systems are distributed.

Reply to the Rejoinder - Grahame holds that it may be that in a services world, a lot of the context that is held in the Act may exist in the service contract.

Conclusion - If Grahame is correct, then this still begs the question of what it means to be compliant to the RIM. Additionally, since services support unity of purpose and non-arbitrary virtualization boundaries, it also is worth asking why we need to create an entity using an "Act"? These are really two ways of asking the same question, though.

Comments welcome and encouraged.

John Koisch


1 comment:

william goossen said...

...RIM will add a new, class called Dependent Continuant (...). This would allow a coherent treatment of diseases, which could be classified by the RIM as Dependent Continuants, leaving observations of disease to be classified, again, under: Act of observation. The new class of Dependent Continuant could then include not only diseases but also qualities such as temperature, blood pressure, etc.

Currently the comments refer to the RIM. However, the actual standards are based on the RIM and formed in the Domain Message Information Models (D-MIM). For example the Care Provision D-MIM. The structure suggested above is already in there. It is called clinical or care statements and it allows to express any observation and each observation can be linked to another, e.g. a disease (value pneumonia) can be visible through observations of temperature (e.g. value 39 degrees Celcius), breathing pattern (e.g. shorness of breath), x-ray (showing the pneumonia in the lungs) etc.
The suggestion to have this additional class is therefore not necessary at all. This disease and its underlying observations on which the clinician has based his conclusion of "pneumonia" can further be linked to the treatment given and can be tracked in the care statement collector.
In other words: what you ask for is already in the HL7 v3 standard, but the RIM is not the whole standard. You look at the wrong sections :-)