While the current QDM specification's definitions of Diagnosis's start datetime and stop datetime are ambiguous, the QRDA Cat I and the HQMF IG define them clearly as onset and resolution dates.

This means that phrases like "Diagnosis, Active: ABC" starts during "Encounter, Performed: XYZ" actually mean that the onset started during the encounter. These "starts during" phrases are used in many measures, but the intent is more likely to be one of the following:

• the condition was the principle diagnosis for the encounter
• the condition was addressed during the encounter
• the condition was diagnosed during the encounter
• the condition was re-asserted (e.g., confirmed) during the encounter

Therefore, there is a mismatch between what is intended and what is specified. At the same time, some measures (that don't use the starts during encounter construct) may in fact intend start datetime to mean onset (particularly measures that use overlaps).

Rather than follow the specification's definitions, vendors seem to interpret the intent of the measures and implement accordingly. Vendors have also indicated that their systems don't always support clear-cut distinctions between onset and assertion datetimes.

FHIR's Condition supports three distinct datetime attributes:

• dateAsserted: "when [the condition was] first detected/suspected/entered"
• onsetDateTime: "when the condition began"
• abatementDate: "when the condition resolved or went into remission"

C-CDA R2's Problem Observation supports the following datetimes:

• effectiveTime: the "biologically relevant time... the time at which the observation holds for the patient"
  • low: "(a.k.a. 'onset date') asserts when the condition became biologically active"
  • high: "(a.k.a. 'resolution date') asserts when the condition became biologically resolved"
• author/time: when the observation was recorded

The QDM user group should specify the Diagnosis datatype's relevant datetime attributes and their precise meanings. It should also indicate the implications for existing measures using these datetime attributes.

(Description expanded and updated 2014/02/02)

UG Accepted Solution

Replace "start datetime" and "stop datetime" attributes with "onset datetime" and "abatement datetime", using the following definitions:

• onset datetime: the estimated or actual date/time that the diagnosis/problem began
• abatement datetime: the estimated or actual date/time that the diagnosis/problem resolved or went into remission

Additional UG Accepted Solution (August 2015)

Add a “recorded datetime” attribute, but ensure that the QDM specification defines it well and notes the caveats that were discussed (see meeting notes in comments).