FAQs about HAI Progress Report

CDC’s HAI Progress Report is a snapshot of how each state and the country are doing in eliminating HAIs. A new version of the report is published every year, with updated data. Each report describes the progress in preventing several HAIs, such as:

• Central line-associated bloodstream infections (CLABSIs) happen when a central line (a tube that a doctor usually places in a large vein of a patient’s neck or chest to give important medical treatment) is not put in correctly or not kept clean. This allows the central line to become a way for germs to enter the body and cause deadly infections in the blood.
• Catheter-associated urinary tract infections (CAUTIs) are infections that involve any part of the urinary system, including urethra, bladder, ureters, and kidney. When a urinary catheter is not put in correctly, not kept clean, or left in a patient for too long, germs can travel through the catheter and infect the bladder and kidneys.
• Ventilator-associated events (VAEs) are problems that patients can experience while on a ventilator (a special breathing machine). This includes infections such as pneumonia or other problems such as fluid buildup in the lungs.
• Surgical site infections (SSIs) are infections that occur after surgery in the part of the body where the surgery took place. Sometimes these infections involve only the skin. Other SSIs can involve tissues under the skin, organs, or implanted material.
• Hospital-onset Clostridioides difficile ( difficile) infections can cause life-threatening diarrhea. When a person takes antibiotics, good bacteria that protect against infection are destroyed for several months. During this time, patients can get sick from C. difficile. This report only includes laboratory identified hospital-onset infections reported.
• Hospital-onset methicillin-resistant Staphylococcus aureus (MRSA) bacteremia (bloodstream infections) is caused by a type of staph bacteria that is resistant to many antibiotics. This report only includes laboratory identified hospital-onset infections reported.

The annual HAI Progress Reports can serve as a reference for anyone looking for information about national and state HAI prevention progress. Each report is based on data reported to CDC’s National Healthcare Safety Network (NHSN). Progress is measured using the standardized infection ratio (SIR), a summary statistic that can be used to track HAI prevention progress over time. Researchers use the reported HAI data to calculate a SIR for the nation and each reporting state.

The report includes national and state-level data reported from acute care hospitals, critical access hospitals, long-term acute care hospitals, and inpatient rehabilitation facilities.

Previous reports prior to 2014 included data from acute care hospitals only.

On any given day, approximately one in 31 U.S. patients has at least one infection contracted during the course of their hospital care, demonstrating the need for improved infection control in U.S. healthcare facilities. Steps can be taken to control and prevent HAIs in a variety of settings. Research shows that when healthcare facilities, care teams, and individual doctors and nurses, are aware of infection problems and take specific steps to prevent them, rates of some targeted HAIs (e.g., CLABSI) can decrease by more than 70 percent.

Infection data can give healthcare facilities and public health agencies information they need to design, implement, and evaluate prevention strategies that protect patients and save lives. CDC fully supports public reporting of HAI data as an important part of overall healthcare transparency efforts and of national HAI elimination.  

This report is a useful tool for federal, state, and local government; healthcare facilities; and patient safety organizations and advocates, all of whom can use these data to lower HAI rates.

Use this report to:

• Measure progress toward the HAI prevention goals outlined in the U.S. Department of Health and Human Services (HHS) Action Plan to Prevent Healthcare-associated Infections and to reach the new HHS proposed targets for December 2020.
• Assess the impact of state-based HAI prevention programs.
• Learn how many facilities in a state are performing significantly worse than the rest of the country.

With more than 24,000 healthcare facilities participating, CDC’s NHSN is the nation’s most widely used HAI tracking system. NHSN provides facilities, states, regions, and the nation with data needed to identify problem areas, measure progress of prevention efforts, and ultimately eliminate HAIs. In addition, NHSN allows healthcare facilities to track antimicrobial use and resistance, blood safety errors and important healthcare process measures such as healthcare personnel influenza vaccine status and infection control adherence rates. Nearly all U.S. hospitals and dialysis facilities are able to successfully report to NHSN, making it an important tool for national HAI tracking and elimination.

Significant progress has been made in some infection types, including CLABSIs, in which a 50% reduction was seen between 2008 and 2016. There have been steady reductions in other infection types as well. To read more about the national progress in reducing HAIs, please see the report HAIs in the United States, 2006-2016: A Story of Progress.

The SIR is a summary statistic that can be used to track HAI prevention progress over time; lower SIRs are better.

If the SIR is more than 1:

There was an increase in the number of infections reported in the nation or state compared to the national baseline.

• A high SIR can reflect a need for stronger HAI prevention efforts.
• Other factors may also play a role in a high SIR, such as intense data validation activities that lead to the discovery and reporting of more infections than in previous years.

If the SIR is 1:

There were about the same number of infections reported in the nation or state compared to the national baseline.

If the SIR is less than 1:

There was a decrease in the number of infections reported in the nation or state compared to the national baseline.

• Usually, a low SIR reflects the results of robust HAI prevention strategies. These scenarios are exciting, and CDC is working with facilities and states to learn and share best practices.
• CDC is also considering the degree, if any, of underreporting in the data.
• It is important to note that this report is not meant to compare states – it is meant to track the results of each state’s prevention efforts over time.
• It is also important to note that while an SIR of less than 1 is a positive finding, it does not mean the work is done. We have made progress toward reducing infections, but research has shown that we can reduce HAI rates even more.

The SUR is a summary statistic that can be used to track device use (such as central line days) compared to similar facilities over time; lower SURs are better. Tracking device use in healthcare settings is an important component of infection prevention, as it measures the exposure of patients to device-associated infections.

If the SUR is more than 1:

Device use was higher than predicted, given the national baseline. A high SUR may reflect the need for additional investigation or review of device utilization practices in that setting.

If the SUR is 1:

There were about the same number of device days reported as were predicted, compared to the national baseline.

If the SUR is less than 1:

Fewer device days were reported than predicted, based on the national baseline. A low SUR may reflect prevention efforts and proper device management practices in that setting.

The SIR compares the number of infections in a facility or state to the number of infections that were “predicted”, or would be expected, to have occurred based on a previous year of reported data (national baseline).

The national SIR is a summary statistic calculated from all reported HAIs that occurred in the country during that year. It is calculated as the total number of observed infections in the country, divided by the total number of predicted infections in the country.

The state SIR is a summary statistic calculated from all reported HAIs that occurred in an individual state during that year. It is calculated as the total number of observed infections from all hospitals in the state, divided by the total number of predicted infections in the state.

National and state SUR metrics are calculated by dividing the total number of reported device days by the predicted number of device days.

The CDC adjusts the SIR and SUR for risk factors that are most associated with differences in infection rates and device utilization. In other words, these metrics take into account the fact that different healthcare facilities treat different types of patients. For example, HAI rates at a hospital that has a large burn unit (where patients are at higher risk of acquiring infections) cannot be directly compared to a hospital that does not have a burn unit. The number of predicted events and predicted device days are calculated based on national baseline data from 2015. 

When the data are risk-adjusted, it makes it possible to fairly compare hospital performance. In this report, the SIRs and SURs are adjusted for risk factors that may impact the number of infections reported by a hospital, such as type of patient care location, bed size of the hospital, patient age, and other factors. For more information, see NHSN’s Guide to the SIR [PDF – 43 pages] or NHSN’s Guide to the SUR [PDF – 26 pages].

The national baseline is aggregated data reported to CDC’s National Healthcare Safety Network (NHSN) during a historical baseline period that is used to “predict” the number of infections, or device days, expected to occur in a hospital, state, or in the country. HAI Progress Reports from 2015 data and forward utilize 2015 as the national baseline.

HAI Progress Reports for data prior to 2015 use the following time periods as the national baseline for the SIR.

Statistical significance is a term used in the context of a statistical hypothesis test to determine if a finding is unlikely to have occurred by chance alone. A statistically significant test result means it is unlikely that the two groups sampled are different simply by chance alone (suggesting that the two populations sampled are, in fact, different). In this report, statistical hypothesis testing is used to compare a calculated standardized infection ratio (SIR) value to the value of 1.0. A statistically significant result from this test means there is statistical evidence that the calculated SIR is different than what would be predicted from the national baseline. In this report, statistical hypothesis testing is also used to compare two SIR values to each other. 

CDC is taking a proactive approach with all states. We offer training and technical assistance to help states identify and assist healthcare facilities whose performance does not show effective prevention work. We encourage states to monitor their SIR so they can aid prevention efforts in problem areas and measure the effects of prevention work over time.

Validation is double-checking, or confirming, HAI data reported CDC’s National Healthcare Safety Network (NHSN). This generally involves an assessment to ensure that all relevant infections were captured in the system. It may also involve checking the accuracy, or quality, of the submitted data.

• CDC encourages healthcare facilities and states to validate the infection data they submit to NHSN.
• Currently, state health departments use different methods to validate HAI data that hospitals submit to NHSN. For example, some states only validate data from one facility while other states validate more widely.
• CDC is working with states to determine best practices and develop effective validation standards.

To learn more about validation definitions used in the current HAI Progress Report, see the report’s Glossary.

Validation efforts should be taken into account when evaluating an individual state’s performance. States that validate data or use advanced methods to detect HAIs may find and report more infections than states that do not validate.

• Healthcare facilities in states that validate data may have greater familiarity and experience using the National Healthcare Safety Network (NHSN) protocol, and they may adhere to that protocol more meticulously knowing that their data may be subject to external validation.
• Not all state health departments have access to NHSN data or have access to NHSN data from every hospital included in this report.