Time and Temporal Qualifications

Most clinical data imply some form of temporal qualification: “Most Recent”, “Current”, “Last Previous”, “Prior/Past”, but also “X time from/since an event”. Unless otherwise stated, that qualification is usually relative to the point in time the data is being evaluated, e.g. for decision making.

Determining If Stored Data Can Be Used for a Decision

Whether a piece of stored data is relevant to a current situation depends on a number of factors:

acuity of the patient’s condition
importance of the data item for making a decision
how much and how fast the data item is affected by a change in health
how accessible or easy it is to obtain

For example, systolic blood pressure in the ICU may only reflect the patient’s current state and is readily measured, so retrieval of value more than a few minutes ago is not relevant, except for trend analysis.

Data Restrictions Relative to an Event

Some clinical or laboratory findings only have meaning relative to an event.

Examples:

On admission or at discharge
Before or after a procedure (dialysis, surgery, etc)
Before or after a drug (peak vs trough levels, response to hormone)

Providing SOLOR Codes for FHIR

The codes used for structuring data sometimes imply some form of temporal qualification, which may be relative to the time the data was/will be captured, and most data is associated to some form of time stamp. This has implications on how the data is represented.

For example: weight today versus weight a year ago: There is a LOINC code for weight, but no separate code for a different date. The solution would be a data structure with fields for date of recording and for weight.