Page Comparison

In the openEHR Entry model, two types are used for 'observations' and 'evaluations'. As with any general terms, these terms are overloaded, causing confusion for some people. In the openEHR model, these two types have a clear purpose. The Observation type is used to record any information derived from the world outside the clinician's head (or any other clinical reasoning device) - i.e. any kind of phenomemon or state of interest to the clinical investigator in the care of the patient. Accordingly, the design of the Observation type defines its data as a History-of-events structure, since all phenomena observed in the external world are situated in time, and in many cases, there are multiple samples to be recorded. In theory, such information should be repeatably observable using the same protocol and assuming a sufficient level of skill or training on the part of the observer.
In contrast, the Evaluation type is used for recording clinical thinking rather than events from the outside world. Consequently, it does not oblige a historical timing structure. This is not to say that 'time' is irrelevant to clinical thinking. Indeed, many typical clinical assessments include all manner of times, as shown by this diagnosis archetype. However, the times in such evaluations are not the primary recording instance of phenomenon or event time of events that may be referred to in the Evaluation, but instead are summarised times, dependent on the kind of assessment being recorded. It may be that no event time is recorded in an Evaluation, such as for the goal archetype, where the only time indicated is future proposed date of achievement.

Thus the Observation type provides the structures for recording phenomena, including statements the patient may make, anything measured or sensed by the clinician, or via using a machine. The history structure provides a standardised way to include the event origin time, and offsets of each event in the series, if it is more than one. In addition, it provides 'state' and 'protocol' (the latter inherited from CARE_ENTRY) which allow the state of the patient (e.g. position, exertion level) and the method (e.g. pulse oximeter) to be recorded alongside the primary data (e.g. heartrate). The history structure of a typical observation is illustrated to the right.

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Clinical Statement

Entry type

Example archetype

Comments

simple measurement

Observation

Body mass index
Dimensions

The simplest 'point' measurements are still situated in time: there is always at least one 'event' or time-point. The openEHR model guarantees that the event-time information in single-point measurements is the same as for mult-sample measurements.

time-series measurement

Observation

Blood pressure measurement
Apgar score
Body Temperature
Glucose Tolerance test

Many phenomena have the potential form of a series of samples in time

difference over time

Observation

Body weight

The History part of the model accommodates changes over time.

maxima, minima, rolling averages etc

Observation

Body Temperature

The 'math function' attribute in the INTERVAL_EVENT class accommodates all kinds of time-based averages and finite duration states.

diagnosis

Evaluation

problem-diagnosis

Times of some events may be mentioned, but the structure of the Entry is not the time-history of an observed phenomenon, but a report or summary, often of several phenomena, supporting a conclusion, which is the point of the Entry.

adverse reaction

Evaluation

Adverse reaction

Adverse reaction assessment is an assessment of condition or propensity of the patient to react to particular substances.