CDC's Healthcare-associated Infection Progress Report: Questions and Answers
About the Report
CDC’s National Healthcare Safety Network enables healthcare facilities to collect and report healthcare-associated infection (HAI) data. CDC, states, healthcare facilities, and other patient safety organizations use this data to identify problem areas, measure progress of prevention efforts, and ultimately eliminate HAIs.
- What is the healthcare-associated infection (HAI) progress report?
- How can I use this report to help prevent healthcare-associated infections?
- What are the benefits of reporting healthcare-associated infection data?
- What makes the National Healthcare Safety Network (NHSN) a good measurement tool?
- Have we made progress in reducing central line-associated bloodstream infections?
- Have we made progress in reducing surgical site infections?
- Have we made progress in reducing catheter-associated urinary tract infections?
- Have we made progress in reducing hospital-onset Clostridium difficile infections?
- Have we made progress in reducing hospital-onset methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections?
- What is the standardized infection ratio?
- How does the CDC calculate the standardized infection ratio?
- What does the standardized infection ratio number mean?
- What is the “predicted number of infections”?
- How many healthcare facilities have a high standardized infection ratio?
- What is CDC doing about healthcare facilities with high standardized infection ratios?
- What is CDC doing about states with high standardized infection ratios?
- What is data validation and why is it important?
- Will states that validate data have higher standardized infection ratios?
About the Report
» What is the healthcare-associated infection (HAI) progress report?
CDC’s HAI progress report is a snapshot of how each state and the country are doing in eliminating HAIs. 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 kept clean. This allows the central line to become a freeway for germs to enter the body and cause serious bloodstream infections.
- Surgical site infections (SSIs) are infections that occur after surgery in the part of the body where the surgery took place.
- Catheter-associated urinary tract infections (CAUTIs) are infections that involve any part of the urinary system, including urethra, bladder, ureters, and kidney.
- Clostridium difficile infections cause potentially deadly diarrhea (national data only)
- MRSA (antibiotic resistant staph bacteria) bloodstream infections can be serious (national data only)
Each report is based on data reported to the CDC’s National Healthcare Safety Network (NHSN). NHSN provides a secure way for healthcare facilities to track HAIs and take action to prevent infections. Researchers use the data to calculate a standardized infection ratio (SIR) for each reporting state and facility.
» How can I use this report to help prevent healthcare-associated infections?
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.
- Assess the impact of state-based HAI prevention programs. The report also indicates how many facilities in my state have significantly more infections than others in the country.
» What are the benefits of reporting healthcare-associated infection data?
Research shows that when healthcare facilities, care teams, and individual practitioners, are aware of infection problems and take specific steps to prevent them, rates of certain HAIs 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 rates as an important part of overall healthcare transparency efforts and of national HAI elimination.
» What makes the National Healthcare Safety Network (NHSN) a good measurement tool?
With more than 12,000 healthcare facilities participating, NHSN is the largest HAI reporting system in the United States. NHSN provides standard methods and definitions, online training modules, user support, and facility comparison tools. 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.
» Have we made progress in reducing central line-associated bloodstream infections?
The current report, when combined with findings from previous reports, shows a national decrease in central line-associated bloodstream infections (CLABSIs). As of 2012, CLABSIs are down nationally by 44 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.
A central line is a narrow tube placed in a large vein of a patient’s neck or chest to give important medical treatment. When not put in correctly or kept clean, a central line can become a highway for germs to enter the body and cause a serious bloodstream infection.
HHS has set a goal of reducing CLABSIs nationally by 50 percent by the end of 2013.
» Have we made progress in reducing surgical site infections?
As of 2012, surgical site infections (SSIs) are down nationally by 20 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 following all procedures except abdominal hysterectomy surgery between 2011 and 2012. 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
HHS has set a goal of reducing SSIs nationally by 25 percent by the end of 2013.
» Have we made progress in reducing catheter-associated urinary tract infections?
As of 2012, catheter-associated urinary tract infections (CAUTIs) are up nationally by 3 percent since 2009. The report shows CAUTIs are down moderately among patients in general wards, but there were significant increases in CAUTIs in critical care patients since 2009. CAUTIs have continued to increase between 2011 and 2012.
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 has a goal of reducing CAUTIs nationally by 25 percent by the end of 2013.
» Have we made progress in reducing hospital-onset Clostridium difficile infections?
As of 2012, hospital-onset Clostridium difficile infections (CDIs) are down nationally by 2% since 2011, which will serve as the comparison year for CDIs in the National Action Plan.
When a person takes or is administered antibiotics, good bacteria that protect against infection are destroyed for several months. During this time, patients can get sick from Clostridium difficile, bacteria that cause potentially deadly diarrhea.
HHS has set a goal of reducing hospital-onset Clostridium difficile infections nationally by 30 percent by the end of 2013.
» Have we made progress in reducing hospital-onset methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections?
As of 2012, hospital-onset MRSA bloodstream infections are down nationally by 4% since 2011, which will serve as the comparison year for MRSA bloodstream infections in the National Action Plan.
MRSA is a type of staph bacteria that is usually spread by direct contact with an infected wound or from contaminated hands. In a healthcare setting, such as a hospital or nursing home, MRSA can cause serious bloodstream infections.
HHS has set a goal of reducing hospital-onset MRSA bloodstream infections nationally by 25 percent by the end of 2013.
» What is the standardized infection ratio?
The standardized infection ratio (SIR) is a summary measure used to track HAIs over time. It compares actual HAI rates in a facility or state with baseline rates in the general U.S. population. 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 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) can not be directly compared to a hospital that does not have a burn unit.
» How does the CDC calculate the standardized infection ratio?
The method of calculating an SIR is similar to the method of calculating the standardized mortality ratio (SMR), a statistic that is widely used by public health researchers to analyze mortality data.
The SIR is adjusted differently depending on the type of infection measured.
The SIRs for CLABSIs and CAUTIs are adjusted by:
- Type of patient care location
- Hospital affiliation with a medical school
- Bed size of the patient care location
The SIRs for hospital-onset Clostridium 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 CDI or an MRSA bloodstream infection (“community-onset” cases)
For hospital-onset CDIs, the SIR also adjusts for the type of test the hospital laboratory uses to identify Clostridium 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:
- Duration of surgery
- Surgical wound class
- Use of endoscopes
- Re-operation status
- Patient age
- Patient assessment at time of anesthesiology
» What does the standardized infection ratio number mean?
If the SIR is less than 1:
- Infection rates have decreased since the baseline period.
- The number of infections reported in 2012 is lower than the number of predicted infections.
- 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.
If the SIR is 1:
- No progress has been made toward reducing infections since the baseline period.
- The number of infections reported in 2012 is the same as the number of predicted infections.
If the SIR is greater than 1:
- Infection rates have increased since the baseline period. The number of infections reported in 2012 is higher than the number of predicted infections.
- 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 data validation that leads to the discovery and reporting of more infections than in previous years.
» What is the “predicted number of infections”?
The predicted number of infections (calculated from a standard population) is an estimate based on CLABSIs and SSIs reported to NHSN in January 2006 through December 2008, CAUTIs reported to NHSN from January to December 2009, and Clostridium difficile and MRSA bloodstream infections reported to NHSN from January to December 2011. The number 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.
» How many healthcare facilities have a high standardized infection ratio?
In each major location group and procedure category, between 6% and 13% of the facilities 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 2012.
|Type of HAI||Number of facilities with high SIR for this HAI in 2012|
|Central line-associated bloodstream infections (CLABSIs)||250|
|Catheter-associated urinary tract infections (CAUTIs)||353|
|Surgical site infections (SSIs) associated with hip arthroplasty||43|
|Surgical site infections (SSIs) associated with knee arthroplasty||40|
|Surgical site infections (SSIs) associated with colon surgery||169|
|Surgical site infections (SSIs) associated with abdominal hysterectomy||53|
|Hospital-onset Clostridium difficile infections||192|
|Hospital-onset MRSA bloodstream infections||45|
In coming years, we can focus prevention efforts on these facilities to make more efficient use of resources.
» What is CDC doing about healthcare facilities with high standardized infection ratios?
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.
» What is CDC doing about states with high standardized infection ratios?
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.
» What is data validation and why is it important?
CDC encourages healthcare facilities and states to validate (double-check) the infection data they submit to NHSN. Validating data usually includes completing an assessment to ensure that all relevant infections were captured in the system.
Currently, different states use different methods to validate data. For example, some states only double-check the data from one facility while other states double-check more widely. CDC is working with states to determine best practices and develop effective validation standards.
» Will states that validate data have higher standardized infection ratios?
The intensity of surveillance makes a difference in case finding. For example, some healthcare facilities commit more resources and advanced tools to detect infections. As a result, they may find more infections. Also, healthcare facilities in states that validate data may have greater familiarity and experience using the NHSN protocol, and they may adhere to that protocol more scrupulously knowing that their data may be subject to external validation. The upshot is that facilities in states that validate HAI data may report more infections, and those states may have higher SIRs. Validation efforts should be taken into account when evaluating an individual state’s SIRs.