Field note · Length of stay

LOS vs GLOS: compare definitions before differences

Executive evidence mapInterpret LOS through separate lenses
01Observed LOS
02Case mix
03Throughput
04Discharge timing
05Placement and access
06Data coverage
The lenses can guide investigation; none alone proves why observed LOS differed from expectation.

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.

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.

What leaders should ask next

  1. What exactly does GLOS refer to in this review?
  2. Which fiscal-year table is matched to these discharges?
  3. How much of the cohort has a valid benchmark?
  4. Would the conclusion change after reviewing the distribution?

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.

Sources and method notes