Metric definitions

Two teams can report different readmission rates from the same data when they count different things. A metric definition fixes the count. It records the metric name, the grain, the numerator and denominator expressions, the unit, the aggregation method and a version, and it points at the outcome definition it serves. Results are calculated against an approved version only, so every published value can be traced to the formula that produced it.

The Metric Steward drafts a definition with Status = 'Draft'. Aggregation is one of Sum, CountDistinct, RatioOfSums, LastAsOf or Median. Another Metric Steward approves the version and is recorded as the reviewer, moving it to Approved. When the formula changes, a new version is drafted and approved, and the earlier one moves to Retired instead of being edited in place.

• Outcome definitions first. Each outcome definition has a code, an organization, effective dates and a policy reference, and metric definitions hang from it.
• Field mappings are versioned. Source mappings record the source and target fields, their types, the transform rule and the date the mapping takes effect.
• Retired versions stay readable. A retired version keeps its grain and expressions so older results still make sense.

Bring the measure specifications you already report: the inclusion and exclusion rules, the numerator and denominator, the reporting grain and the period. Agree how each one maps to the outcome definition’s effective dates and policy reference. Decide who may approve a definition and confirm that the author cannot approve their own draft. Agree the version naming scheme and what happens to in-flight cohorts when a definition is retired.

Draft a thirty-day readmission metric with a RatioOfSums aggregation, a numerator expression for readmissions and a denominator expression for index admissions. Ask the author to approve it; the approval should be refused. Ask a second Metric Steward to approve it and confirm that reviewed by records that person and the status moves to Approved.

Now change the window to fourteen days. The steward should draft a new version, approve it, and retire the thirty-day version. Results already calculated against the thirty-day version should still show that version on the “Metric result windows” view. A cohort built after the change should calculate against the new version only.

• Metric definitions awaiting approval — draft versions with grain, numerator, denominator, aggregation method and the outcome definition they serve.
• Approved metric catalog — approved and retired versions with their unit, aggregation method and reviewer.

• Metric definition to approval: Draft, approve and retire metric definition versions.
• Cohort construction to validation: Build a cohort revision, load its facts and accept or reject each one.

Review the implementation plan and the data model before preparing your import files.