Substance Administration vs Exposure

Using Supply, Exposure and Substance Administration,

The conventional use of Supply is as provision of a stock of medication for a use that is elsewhere modelled – and this is usually as Substance Administration when the medication is actually taken by a patient. Exposure is a new act, but is easily illustrated as inadvertent contact with a toxin. HL7 v3 RIM Classes are named to reflect the characteristics of the real world that they are meant to represent. These three classes illustrate this, but all HL7 classes are an abstract representation of the real world and there may be less obvious real world activities that in the abstract fit the same pattern as a rather distantly related class. This is particularly true when considering Supply, Exposure and Substance Administration and one of the purposes of this note is to suggest a range of activities that are actually one (or more) of Supply, Exposure or Substance Administration even though this may not be evident at first sight.

For instance:

· Recording an apparently allergic reaction to a cosmetic product

· Oiling a machine

· Spraying a crop to kill an aphid infestation

· Formulating a high protein, low sodium diet for a patient

· A celiac patient being given a wheat flour based sauce at a dinner party

· Being given a small part of a course of medication intended for another patient

The second function of this note is to illustrate the normal patterns used within the conventional uses of the three classes, but where questions regularly seem to arise.

For instance

· Giving a patient an infusion

· Immunisation recording

· Providing ward stock

All of these patterns will be illustrated by a brief storyboard, presentation of an RMIM fragment, and an associated discussion. Please note that the model fragments presented are fragments to illustrate the use of the classes of interest. They are not complete, and should not be used as a CMET or Template without further consideration of cardinality, data type and structural attributes.

Peter's Cube

At the Atlanta WGM Peter Goldschmidt presented a Circumstance Context cube representation of the distinction between Substance Administration and Exposure. This cube is presented here. It would be helpful to add analysis in these terms to the examples below.

Recording an apparently allergic reaction to a cosmetic product

Storyboard

Sally Sucker tries a new brand of anti wrinkle cream containing Old English Meade. After three days application of the cream night and morning, her skin develops a scaly, dry appearance and then peels off. She complains to the Cosmetics Watchdog who file a report with the relevant regulatory body.

Use Case

Report that a product was applied to the face night and morning for 3 days. At the end of there was an observation of dry, scaly skin that subsequently peeled.

Data Items to Record

Product: Old English Meade Cream

Site: Face

Method: Rubbed on

Frequency: Night and morning

Duration: 3 days

Observed reaction: 1) Dry scaly skin; 2) Skin peels off

Model Fragment

Discussion

This is a Substance Administration rather than a Supply because we wish to say something specific about the frequency with which the cream was applied and for how long, and also what part of the body the cream was applied to. These attributes are only present in Substance Administration. This is not an exposure event because by definition “[exposure] deals only with opportunity and not the outcome of the exposure”.

Oiling a Machine

…. to be continued