Limitations of FHIR Query

Given the complex nature of the Lung Pathway Map, it became very evident that FHIR Query was not sufficient to execute complex queries that required searching and ordering of instances.

An example of this can be seen when trying to schedule a three, six or twelve month follow-up within a period of five years. The apporach would be to search for all low dose chest CT observations and sort them in ascending order. Then the approaprite upper bound for the time frame could be deduced by taking the date and time for the first chest CT and adding five years. Then and only if the last CT scan was on or before this upper bound would the next follow up be scheduled.

As a result of this complexity we have left CQL place holders to help with querying the necessary content. More information on the use of CQL and the engine can be found here: https://cql.hl7.org/