How Are CMS Star Ratings Calculated?

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Written by Kerry Larkey, MSN, RN Content Writer, IntelyCare
A nurse attends to one of the residents in a nursing home.

Nearly 1.3 million people receive care from the nearly 15,000 nursing homes across the country each day. Choosing a facility can be a stressful and overwhelming experience. The Centers for Medicare & Medicaid Services (CMS) Nursing Home 5-Star Quality Rating System gives the public an easy starting point to compare facilities. But how are CMS Star Ratings calculated?

The CMS 5-Star Ratings are simple and user-friendly for patients, but understanding exactly how the ratings are calculated can be complicated from the perspective of a nurse leader. We’ll break down the rating system to show what data is used and how scores are calculated so you can better understand how it reflects the quality of care your team provides.

What Are CMS Star Ratings for Nursing Homes?

CMS established the 5-Star Quality Rating System to summarize the performance and quality of the nursing homes associated with Medicare and Medicaid. The 5-Star System gives the general public a clear and easy-to-understand tool to evaluate and compare facilities, and also provides important feedback to help nursing homes improve their quality of care. (CMS Star Rating criteria for hospitals are based on different quality metrics.)

Your facility has a rating of between 1 and 5 stars, with 1 star being below average and 5 stars being above average quality. Patients can review ratings showing all four calculated scores using Nursing Home Care Compare.

What Are the Components of a CMS Star Rating?

The overall Star Rating is based on measurements from three individual domains of quality care:

  1. Health inspections based on outcomes from state health inspection surveys
  2. Staffing based on nursing home staffing levels reported at the time of state health inspection
  3. Quality measures — based on the CMS Minimum Data Set (MDS)

We’ll review each of these domains in detail to show how each contributes to the overall Star Rating of your organization. Unless otherwise noted, the information provided in this components section comes from a technical users’ guide referred to as the CMS Care Compare Nursing Home Five-Star Quality Rating. The CMS 5-Star Technical Users’ Guide also contains useful tables and detailed rules for awarding stars.

1. Health Inspection Rating

Health inspection ratings are calculated from points assigned as the result of nursing home surveys over the past three years, complaint surveys from the past three years, and survey revisits. The most recent surveys are weighted more heavily. Because state guidelines vary across the nation, nursing homes are ranked within their state using the following distribution:

  • The top 10% get 5 stars
  • The bottom 20% get 1 star
  • The middle 70% get 2, 3, or 4 stars, with equal proportions (23.33%) in each category

CMS also created an “abuse icon” on Nursing Home Care Compare to alert the public to which facilities have non-compliance issues related to abuse. Facilities with abuse citations can only receive a maximum of 2 stars in this category.

2. Staffing

For some time, patient outcomes and safety have been closely linked to nurse staffing. Nurse-to-patient ratios are measured along with nursing turnover. Higher turnover is linked with poorer quality of care. For this domain, staffing measurements are collected during state survey visits. The domain is based on six measures:

  1. Case-mix adjusted total nursing hours per resident day (registered nurse (RN) + licensed practical nurse (LPN) + nurse aide hours) for a quarter averaged across all days (weekdays and weekends)
  2. Case-mix adjusted RN hours per resident day for a quarter, averaged across all days (weekdays and weekends)
  3. Case-mix adjusted total nursing hours per resident day (RN + LPN + nurse aide hours) for a quarter averaged across all weekend days (Saturdays and Sundays)
  4. The percentage of nursing staff that left the nursing home over a 12-month period
  5. The percentage of RNs that left the nursing home over a 12-month period
  6. The number of administrators that left the nursing home over a 12-month period

The number of nurses per resident is often low, with 75% of nursing homes failing to meet CMS’s expected registered nurse staffing levels based on residents’ acuity. If a nursing home doesn’t submit staffing data by the deadline, they’ll automatically receive a 1 Star rating. CMS also conducts periodic audits to check for accuracy of the data that is submitted.

3. Quality Measures

Given the often-subjective nature of the term, just how are CMS Star Ratings calculated for a facility’s quality of care? CMS has identified a set of 15 quality measures for short- and long-stay residents to define the quality of care at your facility. Ten are from the Minimum Data Set, Version 3.0 (MDS 3.0) Quality Measures (QM), and five are from Medicare claims data. These data sets provide a wide range of patient health indicators to show the overall quality of nursing care.

Quality Measures Claims Data
  • Pressure ulcers
  • Moderate to severe pain
  • Delirium
  • Percentage of short-stay residents re-hospitalized after a nursing home admission
  • Percentage of short-stay residents who had an outpatient emergency department visit
  • Rate of successful return to home and community from nursing home
  • ADL decline
  • Mobility decline
  • Catheter
  • High-risk pressure ulcers
  • Physical restraints
  • Urinary tract infections
  • Moderate to severe pain
  • Number of hospitalizations per 1,000 long-stay resident days
  • Number of outpatient emergency department visits per 1,000 long-stay resident days

How Are Medicare Star Ratings Calculated?

Once each of the three main domains have been scored, how are CMS Star Ratings calculated? It’s actually a simple process. According to the CMS Brief Explanation of Five-Star Technical Users’ Guide, the overall 5-Star Rating is worked out in five steps. This CMS 5-Star Rating calculator shows each step of the process:

1 Enter the Health Inspection Rating.  
2 Add one star if the Staffing rating is 4 or 5 stars and also greater than the Health Inspection Rating. Subtract one star if the Staffing rating is 1 star.* +/- 1 star
3 Add one star if the Quality Measure rating is 5 stars; subtract one star if the Quality Measure is 1 star.*  +/- 1 star
4 If the Health Inspection rating is 1 star, then the overall Quality rating can’t be upgraded by more than one star based on the Staffing and Quality Measure ratings.  
5 If a nursing home is a Special Focus Facility that has not graduated, the maximum Overall Quality rating is 3 stars.  
Overall Five-Star Rating:  

* The rating can’t go above 5 stars or lower than 1 star.

Looking for More Ways to Boost Your Quality of Care?

Now that we’ve answered the question, How are CMS Star Ratings calculated? you may be curious about ideas for cultivating quality metrics with your team. If you’re looking for extra resources to launch quality and safety programs in your facility, IntelyCare is your trusted source for information. Our newsletter is full of free nursing management insights to support healthcare managers.