How to Read CMS Dialysis Star Ratings

Every Medicare-certified dialysis facility in the United States receives a Quality of Patient Care star rating from the Centers for Medicare & Medicaid Services (CMS). The rating ranges from 1 star (much below average) to 5 stars (much above average). Here is what the rating actually measures and how to use it.

What the overall star rating includes

The overall star rating is a composite of nine clinical quality measures:

1. Standardized Mortality Ratio (SMR) — Are patients surviving at expected rates?
2. Standardized Hospitalization Ratio (SHR) — Are patients being hospitalized more or less than expected?
3. Standardized Readmission Ratio (SRR) — Are patients being readmitted to the hospital more than expected?
4. Emergency Department Visits — How often do patients end up in the ER?
5. Standardized Transfusion Ratio (STrR) — Are patients receiving blood transfusions more than expected?
6. Bloodstream Infection Ratio (SIR) — Are catheter-related bloodstream infections higher or lower than expected?
7. Fistula Rate — What percentage of patients use an AV fistula for dialysis access?
8. Long-term Catheter Rate — What percentage of patients use a long-term catheter?
9. Hypercalcemia Rate — What percentage of patients have high calcium levels?

CMS applies a statistical clustering algorithm to assign star ratings. The ratings are relative — meaning they compare each facility to all other facilities nationally, not to a fixed standard.

How to interpret the ratios

Several of the most important measures are expressed as standardized ratios. Here is how to read them:

• A ratio of 1.0 means the facility performs exactly as expected given its patient population
• A ratio below 1.0 means the facility performs better than expected (fewer deaths, hospitalizations, or infections)
• A ratio above 1.0 means the facility performs worse than expected

For example, a Standardized Mortality Ratio of 0.85 means patients at that facility die at 85% of the expected rate — better than average. An SMR of 1.15 means patients die at 115% of the expected rate — worse than average.

What the star rating does not tell you

Star ratings are useful but imperfect. Some limitations:

• Data lags: Ratings are based on data from previous quarters and may not reflect recent changes in facility management or staffing
• Small-volume facilities: Clinics with fewer patients may have statistically less reliable ratios
• Patient mix adjustments: CMS adjusts for patient demographics and comorbidities, but no adjustment is perfect
• Transplant referrals are not included: The star rating does not penalize facilities for low transplant referral rates, even though getting on the transplant waitlist is often the best outcome for a patient

How to use star ratings wisely

Star ratings are one input, not the only input. Use them alongside:

• Conversations with your nephrologist about your specific medical needs
• The facility's transplant referral rate (available on each facility page)
• Whether the facility offers home dialysis or peritoneal dialysis, if relevant to you
• The facility's infection rate, especially if you use a catheter
• Practical factors like location, schedule availability, and staff communication

A 5-star facility that is a 90-minute drive away may not be the right choice if a solid 3-star facility is 10 minutes from your home. Context matters.