HAI Progress Report FAQ

CDC’s HAI Progress Report is a snapshot of how each state and the country are doing in eliminating HAIs. The most recent HAI Progress Report includes 2014 data, published in 2016. Each report describes the progress in preventing the following types of HAIs:

• 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.
• 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 Clostridium difficile (C. 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 each reporting state and facility.

The report includes national and state-level data from acute care hospitals for

• central line-associated bloodstream infections (CLABSI),
• catheter-associated urinary tract infections (CAUTI),
• surgical site infections (SSI),
• hospital-onset Clostridium difficile infections (C. difficile), and
• hospital-onset methicillin-resistant Staphylococcus aureus (MRSA) bacteremia (bloodstream infections).

Previous reports included data from acute care hospitals only. For the first time, the report (2014 data, published 2016) includes national data from two additional facility types.

• Long-term acute care hospitals (LTACHs): CLABSI and CAUTI data
• Inpatient rehabilitation facilities (IRFs): CAUTI data only

On any given day, about one in 25 hospital patients has at least one healthcare-associated infection. 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 17,000 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.

The current report shows a national decrease in central line-associated bloodstream infections (CLABSIs). As of 2014, CLABSIs are down nationally by 50 percent since 2008. These encouraging findings reflect the work of care teams, individual practitioners, and facilities; local, state, and federal government; and cross-cutting partnership groups that have taken on CLABSI prevention efforts. We hope that all states and healthcare facilities will be motivated to continue and strengthen efforts to prevent CLABSIs.

HHS set a goal of reducing CLABSIs nationally by 50 percent by the end of 2013. In 2014, CLABSI in acute care hospitals reached this goal, decreasing 50 percent between 2008 and 2014. The new HHS proposed targets for December 2020 will use calendar year 2015 data reported to CDC’s National Healthcare Safety Network (NHSN) as the baseline.

As of 2014, surgical site infections (SSIs) from 10 select procedures are down nationally by 17 percent since 2008; however, there is a wide variation in SSI rates for specific surgical procedures. US hospitals reported a significant decrease in the number of SSIs between 2013 and 2014 from 2 procedure types: cardiac and rectal surgeries. While these results are encouraging, we, as a healthcare community, still have opportunities to improve prevention efforts across many surgical procedures.

The report includes a national snapshot of the infection risk linked to the following common surgical procedures:

• Hip or knee arthroplasty
• Coronary artery bypass graft
• Cardiac surgery
• Peripheral vascular bypass surgery
• Abdominal aortic aneurysm repair
• Colon or rectal surgery
• Abdominal or vaginal hysterectomy

For the first time, the report (2014 data, published 2016) includes the additional 29 surgical procedures reported to CDC’s National Healthcare Safety Network (NHSN). To learn more about national progress in SSIs, see the full report.  

HHS set a goal of reducing SSIs nationally by 25 percent by the end of 2013. The new HHS proposed targets for December 2020 will use calendar year 2015 data reported to NHSN as the baseline.

As of 2014, catheter-associated urinary tract infections (CAUTIs) have not changed nationally since 2009. However, there was progress in non-ICU settings between 2009 and 2014, progress in all settings between 2013 and 2014, and even more progress in all settings towards the end of 2014.

Reducing CAUTI among critical care patients is a special concern because these infections drive antibiotic use. While antibiotics are essential for treating bacterial infections, they also increase patients’ risk for complications. One potentially deadly complication is severe diarrhea caused by the bacteria Clostridium difficile.

HHS set a goal of reducing CAUTIs nationally by 25 percent by the end of 2013. The new HHS proposed targets for December 2020 will use calendar year 2015 data reported to CDC’s National Healthcare Safety Network (NHSN) as the baseline.

As of 2014, hospital-onset C. difficile infections are down nationally by 8 percent since 2011.

HHS set a goal of reducing hospital-onset C. difficile infections nationally by 30 percent by the end of 2013. The new HHS proposed targets for December 2020 will use calendar year 2015 data reported to CDC’s National Healthcare Safety Network (NHSN) as the baseline.

As of 2014, hospital-onset MRSA bloodstream infections are down nationally by 13 percent since 2011.

HHS set a goal of reducing hospital-onset MRSA bloodstream infections nationally by 25 percent by the end of 2013. The new HHS proposed targets for December 2020 will use calendar year 2015 data reported to CDC’s National Healthcare Safety Network (NHSN) as the baseline.

For the first time, the report (2014 data, published 2016) includes national data from two additional facility types.

• Long-term acute care hospitals (LTACHs) reported a 9 percent decrease in CLABSI and an 11 percent decrease in CAUTI between 2013 and 2014.
• Inpatient rehabilitation facilities (IRFs) reported a 14 percent decrease in CAUTI between 2013 and 2014.

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 compared to the national baseline.

• A high SIR usually reflects 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 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 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 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 previous years of reported data (national baseline).

The national 2014 SIR is a summary statistic calculated from all reported HAIs that occurred in the country in 2014. It was calculated as the total number of observed infections in the country, divided by the total number of predicted infections in the country in 2014.   

The state 2014 SIR is a summary statistic calculated from all reported HAIs that occurred in an individual state in 2014. It was 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 in 2014.   

The CDC adjusts the SIR for risk factors that are most associated with differences in infection rates. In other words, the SIR takes 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.

When the data are risk-adjusted, it makes it possible to fairly compare hospital performance. In this report, the SIRs 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. The SIR is adjusted differently depending on the type of infection measured.

The SIRs for CLABSIs and CAUTIs are adjusted for:

• Type of patient care location
• Hospital affiliation with a medical school
• Bed size of the patient care location

The SIRs for hospital-onset C. difficile and MRSA bloodstream infections are adjusted using slightly different risk factors:

• Facility bed size
• Hospital affiliation with a medical school
• The number of patients admitted to the hospital who already have C. difficile or an MRSA bloodstream infection (“community-onset” cases)
• For hospital-onset C. difficile, the SIR also adjusts for the type of test the hospital laboratory uses to identify C. difficile from patient specimens.

The SIRs for SSIs take into account patient differences and procedure-related risk factors within each type of surgery. These risk factors include, but are not limited to:

• Duration of surgery
• Surgical wound class
• Use of endoscopes
• Re-operation status
• Patient age
• Patient assessment at time of anesthesiology

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 expected to occur in a hospital, state, or in the country. In this report, the number of predicted infections is an estimate based on data reported to NHSN during the following time periods.

Infection types presented have different baseline years for comparison. Moving forward, HAI prevention progress for future years will be measured in comparison to infection data from 2015.

The number of predicted infections is risk-adjusted and includes data from all facilities, whether or not they are under state mandates. To calculate a state or facility’s SIR for a certain time period, CDC compares the predicted number of infections based on the standard population to the number of infections reported in that time period.

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 data. In this report, statistical hypothesis testing is also used to compare two SIR values to each other.

For each major HAI type, between 2 percent and 12 percent of the facilities in the country reported an SIR significantly greater than the national SIR in each category.

The following table shows the total number of facilities that had an SIR significantly greater than the national SIR for different types of HAIs. These numbers are relatively small compared to the total number of facilities that reported data in 2014.

CDC is contacting these facilities and connecting them with prevention initiatives such as:

• State health department collaboratives
• Comprehensive Unit-based Safety Program (CUSP)
• Partnership for Patients
• CMS Quality Improvement Organizations

By moving these hospitals towards more prevention, we hope to see greater national reductions in HAIs next year.

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 developeffective 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.