Overview of the CMS Star Rating System
The Centers for Medicare and Medicaid Services (CMS) publishes star ratings for nearly all Medicare- and Medicaid-certified nursing homes in the United States through its Care Compare database, available at medicare.gov/care-compare. The system assigns each facility an overall rating of one to five stars, where one star indicates quality below the national average and five stars indicates quality above the national average. As of 2024, more than 15,000 nursing homes are rated within this system. The ratings are designed to give consumers, researchers, and policymakers a standardized basis for comparing facilities across different states and markets.
CMS introduced the Five-Star Quality Rating System in December 2008. The methodology has been revised several times since then, with significant updates in 2015, 2019, and 2022, each aimed at improving the accuracy and transparency of the underlying data. The Care Compare database is the authoritative source for all current ratings and is updated on a rolling basis as new inspection results, staffing data, and quality measure data become available.
How CMS Calculates the Overall Rating
The overall star rating is not a simple average of the three component ratings. CMS uses a structured algorithm in which the health inspection rating serves as the starting point. The overall rating begins with the health inspection star value and then adjusts upward or downward based on the staffing and quality measure ratings under specific rules.
The adjustment rules operate as follows:
- If a facility receives five stars on the staffing component, one star is added to the health inspection baseline.
- If a facility receives one star on the staffing component, one star is subtracted from the health inspection baseline.
- If a facility receives five stars on the quality measures component, one star is added to the adjusted total.
- If a facility receives one star on the quality measures component, one star is subtracted from the adjusted total.
After adjustments, the overall rating is capped at five stars and floored at one star. A facility cannot receive a five-star overall rating if it has received one star on the health inspection component. This structural constraint reflects CMS's position that on-site inspection findings represent the most direct measure of resident safety and regulatory compliance.
The Three Component Ratings Explained
Each overall rating is composed of three distinct domain scores. Understanding each domain helps contextualize the overall rating.
Health Inspection Rating. This component is based on findings from standard annual surveys conducted by state survey agencies on behalf of CMS, as well as complaint investigations. Surveys assess compliance with federal regulations covering resident care, infection control, staffing adequacy, and facility conditions. The health inspection rating accounts for survey results from the most recent three years, with greater weight assigned to the most recent 12-month period. Approximately 54 percent of the total inspection score weight applies to the most recent year of data.
Staffing Rating. This component evaluates nursing staff levels relative to the resident census. CMS examines two staffing measures: total nurse staffing hours per resident per day and registered nurse (RN) hours per resident per day. Since 2018, CMS has used payroll-based journal (PBJ) data submitted directly by facilities to calculate staffing hours, replacing the prior self-reported system. The staffing rating also applies an acuity adjustment using MDS (Minimum Data Set) assessments to account for facilities serving residents with higher care needs.
Quality Measures Rating. This component uses clinical data from resident assessments and Medicare claims to evaluate outcomes across a set of standardized measures. As of 2023, CMS uses 15 quality measures for long-stay residents and 5 for short-stay residents. Example measures include the percentage of long-stay residents with pressure ulcers, the percentage experiencing falls with major injury, and the rate of hospitalizations among short-stay residents. Each measure is weighted equally within the quality measures domain.
Deficiency Scope and Severity in Health Inspections
Health inspection deficiencies are classified along two dimensions: scope and severity. Scope describes how widespread a problem is, ranging from isolated to widespread. Severity describes the potential or actual harm caused, ranging from no actual harm with potential for minimal harm to immediate jeopardy to resident health or safety. CMS plots each deficiency on a grid using letters A through L, where A represents the lowest scope and severity combination and L represents the most serious. Deficiencies at the J, K, or L level indicate immediate jeopardy and carry the heaviest penalties in the scoring algorithm.
The health inspection score is calculated by summing weighted point values for each deficiency cited during the survey period. Higher-severity citations carry substantially more weight. For instance, an immediate jeopardy citation can add more points to a facility's deficiency score than dozens of lower-level citations combined. Facilities are ranked against national distributions, and those with higher deficiency point totals receive fewer stars. A facility cited with even one immediate jeopardy deficiency in the most recent standard survey cannot receive more than two stars on the health inspection component, regardless of other findings.
Staffing Hours Per Resident Day
Staffing levels are expressed as hours per resident day (HPRD), a metric that represents the total nursing hours worked divided by the average daily census. CMS evaluates both total nurse HPRD, which includes RNs, licensed practical nurses (LPNs), and certified nursing assistants (CNAs), and RN-only HPRD as a separate sub-measure. As of 2022, the national average for total nurse staffing was approximately 3.8 HPRD, while RN-only staffing averaged around 0.5 HPRD.
The PBJ system requires facilities to submit actual payroll records on a quarterly basis, reducing the risk of inflated staffing reports that were common under the previous self-reported model. CMS also applies case-mix adjustment to these figures, recognizing that facilities serving residents with complex medical needs require proportionally higher staffing levels. A facility with an adjusted RN HPRD below a defined threshold will automatically receive one star on the staffing component, regardless of total nurse HPRD scores.
Common Misconceptions and Limitations of the Rating System
Several misconceptions are frequently associated with the Five-Star system. The most common is that a five-star overall rating implies five-star performance in all three components. This is incorrect. Because of the algorithmic structure, a facility may reach five stars overall with a three-star health inspection rating, provided its staffing and quality measure ratings are sufficiently high. Consumers relying solely on the overall rating may overlook meaningful variation in individual domains.
Additional limitations of the system include the following:
- Survey frequency. Standard annual surveys may occur anywhere from 9 to 15 months apart, meaning inspection data can be up to 15 months old at any given point. Conditions at a facility may change substantially between surveys.
- Self-reported quality measure data. Although staffing data shifted to payroll verification in 2018, quality measure data is still drawn largely from MDS assessments completed by facility staff. Inconsistent coding practices across facilities can affect comparability.
- State variation in survey stringency. Federal research has documented that state survey agencies apply federal standards with varying degrees of rigor, meaning a five-star health inspection rating in one state may not reflect the same deficiency threshold as in another state.
- Exclusion of certain quality domains. Resident and family satisfaction surveys, staff turnover rates beyond a basic measure, and financial stability indicators are not incorporated into the star rating, limiting the scope of what the rating captures.
- Lag in data updates. Quality measure data typically reflects a rolling 12-month period ending several months before publication, meaning the Care Compare database does not represent real-time facility performance.
Researchers and consumer advocates recommend using CMS Care Compare star ratings as one input among several when evaluating nursing home quality, supplementing the data with direct facility visits, review of recent inspection reports, and consultation with local long-term care ombudsman programs.