In the current QDM, a diagnosis can be flagged as the principal diagnosis via the ordinality attribute. Unfortunately, there is not a way to indicate the encounter it is principal for except through timing (which is inexact and relies on a misunderstood meaning of start datetime).

FHIR's Condition does not support a notion of ordinality or principal directly. FHIR does support the following relationships between Condition and Encounter:

• Condition.encounter is a reference to the "encounter when the condition first asserted"
• Encounter.reason is a code representing the "reason the encounter takes place" (which could be a code for a condition type)
• Encounter.indication is a reference to the resource representing the "reason the encounter takes place" (which could be a Condition)
• Encounter.dischargeDiagnosis is "the final diagnosis given a patient before release from the hospital after all testing, surgery, and workup are complete"

In addition, FHIR's InstitutionalClaim and ProfessionalClaim support ordered lists of diagnoses (using ICD-10 codes), and a list of conditions.

C-CDA R2's Problem Observation also does not support a notion of ordinality or principal directly. C-CDA R2's Encounter Activity may contain an:

• EncounterDiagnosis that "wraps relevant problems or diagnoses at the close of a visit or that need to be followed after the visit. If the encounter is associated with a Hospital Discharge, the Hospital Discharge Diagnosis must be used."
• Indication representing the "rationale for an action such as an encounter."

The QDM user group should determine how best to represent a principal diagnosis and associate it with the correct encounter. QDM-102 further suggests that it should support both the legal meaning of principal (billing) and the clinical meaning of principal (primary). Comments in QDM-40 also suggest that support for secondary should be maintained, if possible.

UG Accepted Solution

Add "diagnosis" and "principal diagnosis" attributes to Encounter:

• diagnosis: a diagnosis/problem addressed during the encounter (code)
• principal diagnosis: the diagnosis/problem established after study to be chiefly responsible for occasioning the admission of the patient to the hospital for care (code)

Note that the QDM architecture does not allow these attributes to reference full datatypes, so instead, they reference codes.

Where current measures specify principal diagnoses like this:

“Diagnosis, Active: Asthma (ordinality: Principal)” starts during “Encounter, Performed: Inpatient”

The new solution allows them to be expressed in a cleaner, more reliable way:

“Encounter, Performed: Inpatient (principal diagnosis: Asthma)”