- Observed LOS
- Case mix
- Throughput
- Discharge timing
- Placement and access
- Data coverage
01 · Working principle
A comparison is only as clear as its reference
Leaders should be able to name the observed cohort, LOS convention, discharge period, benchmark source, fiscal year, matching logic, and aggregation method in one sentence. If those details do not fit in the review, the headline comparison is not ready.
CMS Table 5 publishes geometric and arithmetic mean length of stay by MS-DRG alongside relative weights. That is a useful public reference for a defined purpose; it is not a patient-specific forecast and should not be presented as one. Comparing an observed arithmetic mean with a geometric reference requires an explicitly documented aggregation method; they are different statistical summaries.
02 · Working principle
Five checks before interpretation
Run the checks before ranking services or assigning operational explanations.
- Cohort: apply the same inclusion, exclusion, and transfer rules.
- Definition: use one documented start-and-end convention.
- Vintage: match the reference to the applicable fiscal year.
- Coverage: report eligible, matched, unmatched, and excluded counts.
- Distribution: inspect tails and subgroup movement before relying on the mean.
Executive checklist
What leaders should ask next
- What exactly does GLOS refer to in this review?
- Which fiscal-year table is matched to these discharges?
- How much of the cohort has a valid benchmark?
- Would the conclusion change after reviewing the distribution?
Interpretation boundary
Limits to keep visible
- A difference between observed LOS and a benchmark is not itself avoidable time or proof of inefficiency.
- CMS geometric mean LOS is a reference attached to an MS-DRG table, not a patient-level prediction.
- sanalytics does not promise that its use will reduce length of stay.
Authoritative references
Sources and method notes
References reviewed September 28, 2026. They support the definitions and governance context; the operating-review guidance is sanalytics’ editorial interpretation, not an endorsed industry standard.
- Centers for Medicare & Medicaid Services: MS-DRG Classifications and Software
Official MS-DRG classifications, software, and effective periods, including midyear grouper updates. Use the version applicable to the discharge date.
- Centers for Medicare & Medicaid Services: FY 2026 IPPS Final Rule Home Page
FY 2026 Table 5 includes MS-DRG relative weights and geometric and arithmetic mean length of stay. It is a named reference year, not a recommendation to use FY 2026 for every cohort.