SNF Insights guide
MDS Data: Two Datasets, Two Different Questions
CMS publishes the Minimum Data Set, the clinical assessment every certified nursing home completes for each resident, in two facility-level files: 17 scored quality measures, and response frequencies for several hundred assessment items. Only 8 of the 17 measures feed the Five-Star quality rating.
Updated October 2026 · Sources: CMS MDS Quality Measures, Medicare Claims Quality Measures and SNF QRP files (Provider Data Catalog); Facility-Level MDS Frequency (data.cms.gov); Five-Star Technical Users’ Guide, September 2026
Two files answer two different questions
| File | What it holds | What it answers |
|---|---|---|
| MDS Quality Measures | 17 measures (14 long-stay, 3 short-stay), each with four quarterly scores and a four-quarter average | How is this facility performing? |
| Facility-Level MDS Frequency | For each assessment item, the share of active residents giving each response, overall and by short and long stay | What is this facility’s resident population like? |
Both are updated quarterly and key on the facility CCN. The quality measures are on CMS’s Provider Data Catalog; the frequency file is on data.cms.gov. The frequency file is far larger: one facility’s Q4 2023 report has 2,282 rows covering 567 items. Resident-level records are not public.
Only 8 of the 17 measures feed the star rating, and 7 rating measures sit in other files
The Five-Star quality measure rating uses 15 measures: 10 built from MDS assessments and 5 from Medicare claims. Only 8 of them are in the MDS Quality Measures file, where a column flags each one used in the rating. The other 9 measures in that file (weight loss, depressive symptoms, restraints, incontinence, antianxiety or hypnotic use, and four vaccination measures) are published but cannot move the rating.
| Group | Measures in the QM rating | Published in |
|---|---|---|
| Long-stay, MDS (7) | Help with daily activities increased; walking worsened; pressure ulcers; catheter; urinary tract infection; falls with major injury; antipsychotic use | MDS Quality Measures |
| Short-stay, MDS (3) | New antipsychotic use; discharge function score; new or worsened pressure ulcers/injuries | MDS Quality Measures (first); SNF Quality Reporting Program (other two) |
| Long-stay, claims (2) | Hospitalizations and outpatient ED visits per 1,000 resident days | Medicare Claims Quality Measures |
| Short-stay, claims (3) | Rehospitalization; outpatient ED visit; successful return to home and community | Medicare Claims Quality Measures (first two); SNF Quality Reporting Program (third) |
Five-Star Technical Users’ Guide, September 2026. Long-stay means more than 100 days in the home.
Long-stay measures can earn up to 1,150 points and short-stay measures are scaled to the same 1,150, for 2,300 in total. As of CMS’s July 2026 thresholds, 5 stars takes 1,494 points. CMS raises the thresholds every six months by half the average improvement in scores, so a home whose scores hold steady can lose stars. More in how the CMS Five-Star rating works.
Scores are four-quarter averages, so one quarter counts for a year
Each row of the MDS Quality Measures file carries four quarterly scores and their average. The current file covers 2025Q2 to 2026Q1, except the two flu vaccination measures, which run a season behind (2024Q3 to 2025Q2). A bad quarter stays in the average until it rolls off four quarters later. The claims-based measures use a full year of data, and successful return to home and community uses two.
Long-stay and short-stay measures cover different residents with different denominators, so a long-stay rate and a short-stay rate are not comparable to each other.
SNF Insights carries the quality measures and the item frequencies alongside staffing, survey history and financials.
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