1 Executive Summary

Pennsylvania was one of the first states to recognize the harmful impact that healthcare-associated infections (HAIs) had on patient outcomes and quality of life related to additional medical treatment, loss of time, and financial burden. As a result, in 2007, the Pennsylvania General Assembly amended the Medical Care Availability and Reduction of Error (MCARE) Act by adding a new chapter (Pennsylvania Act 52) to address the reduction and prevention of HAIs in Pennsylvania. This law includes requirements for hospitals to report all HAI events into the National Healthcare Safety Network (NHSN), a secure internet-based data collection/reporting system managed by the Division of Healthcare Quality Promotion at the Centers for Disease Control and Prevention (CDC). The use of NHSN provides standardized HAI case definitions and allows for analysis and comparison to hospitals located throughout the nation. As required by Act 52, the Pennsylvania Department of Health (Department) analyzes HAI data reported to NHSN, summarizes the findings and releases an annual report that documents progress that Pennsylvania hospitals have made in implementing HAI prevention strategies to encourage statewide reduction of HAIs.

This 2021 report is the 14th report to be released by the Department and the sixth to use an interactive online format. These data were not compared with prior years to assess the impact of the COVID-19 pandemic on the HAI incidence. The reader must be aware that this report does not include data from nursing homes, long-term care facilities, ambulatory surgical centers, or other outpatient care centers and only includes information from Pennsylvania acute care, critical access, inpatient rehabilitation, long-term acute care, psychiatric, and children’s hospitals for the calendar year 2021. Other HAIs occur but are not included in this report. These may include respiratory illnesses and surgical site infections that follow other types of surgeries. Results are presented for two device utilization rates, surgical site infections (SSI) following seven types of surgical procedures, and two proxy infection events [Laboratory-Identified Events (LabID)]. Included are:

  1. Central line-associated bloodstream infections (CLABSI)
  2. Catheter-associated urinary tract infections (CAUTI)
  3. Surgical site infections for seven procedure types
    • Abdominal hysterectomies (HYST)
    • Colon surgeries (COLO)
    • Cardiac surgeries (CARD)
    • Coronary bypass with chest incision and donor incisions (CBG with two incisions)
    • Coronary bypass with chest incision only (CBG with one incision)
    • Hip prosthesis (HPRO)
    • Knee prosthesis (KPRO)
  4. Urinary catheter utilization
  5. Central line utilization
  6. Clostridioides difficile lab events (CDI LabID)
  7. Methicillin-resistant Staphylococcus aureus blood specimen events (MRSA LabID)

This report presents HAI results using two NHSN metrics to gauge the progress in reducing HAIs.

  1. The standardized infection ratio (SIR) compares the number of reported infections with the number of predicted infections based on 2015 baseline data. It adjusts for several risk factors that have been found to be significantly associated with differences in infection incidence. Factors may be either facility-related or, for surgical site infections, patient characteristics.

\[ SIR = \frac{Number \: of \: Reported \: HAIs}{Number \: of \: Predicted \: HAIs} \]

  1. The standardized utilization ratio (SUR) compares the number of device days reported to the number of predicted device days based on 2015 national baseline data. It adjusts for facility characteristics.

\[ SUR = \frac{Number \: of \: Reported \: device \: days}{Number \: of \: Predicted \: device \: days} \]

The SIR and SUR are useful metrics to compare one facility to similar facilities in the rest of the country and to track progress within a single facility over time. Below are rules to interpret the value of a SIR:

  • If the SIR is greater than 1.0, then more HAIs were reported than predicted, based on the 2015 national baseline data.
  • If the SIR equals 1.0, then the same number of HAIs were reported as predicted, based on the 2015 national baseline data.
  • If the SIR is less than 1.0, then fewer HAIs were reported than predicted, based on the 2015 national baseline data.

Comparisons of SIR or SUR values from different years can only be made when the baseline data are from the same time frame. Readers are cautioned not to compare SIR values in this report to Pennsylvanian HAI reports prior to 2016. The SIR values in this report can be compared to data from annual reports generated after 2015 and CDC HAI progress reports that use the 2015 national baseline.

To fully interpret SIR or SUR values, it’s best to examine not only how large or small the value is when compared to 1.0, but also examine the 95% confidence interval (CI). The 95% CI is a range of values in which a high degree of confidence exists that the true SIR or SUR lies within that range. If the number 1.0 does not fall within the range, the SIR or SUR is considered “statistically significant.” The combination of both approaches is considered the best way to evaluate a SIR or SUR value. Below are rules for interpreting the 95% CI.

95% Confidence Interval:

  • The 95% CI is a range of values in which a high degree of confidence exists that the true SIR or SUR lies within that range.
  • If the CI does not include 1.0, then the SIR is significantly different than 1.0 (i.e., the number of reported infections is significantly different than the number predicted).
    • Example 1: 95% CI = (0.85, 0.92). One can be 95% certain that the true SIR value is between 0.85 and 0.92 and less than 1.0.
    • Example 2: 95% CI = (1.08, 1.22). One can be 95% certain that the true SIR value is between 1.08 and 1.22 and more than 1.0.
  • If the CI includes the value of 1.0, then the SIR is not significantly different than 1.0 (i.e., the number of reported infections is not significantly different than the number predicted).
    • Example: 95% CI = (0.85, 1.24). One can be 95% certain that the true SIR value is between 0.85 and 1.24 and is not different than 1.0.
  • If the SIR is 0.000 (i.e., the infection count is 0 and the number of predicted infections is 1.0 or more), the lower bound of the 95% CI will be zero.
    • Example: 95% CI = (0, 1.49). One can be 95% certain that the true SIR value is between 0 and 1.49 and is not different than 1.0.
    • Example: 95% CI = (0, 0.85). One can be 95% certain that the true SIR value is between 0 and 0.85 and is less than 1.0.

The SIR and SUR are calculated using aggregate data reported by Pennsylvania hospitals that were open for all 12 months in 2021 and are presented for the entire commonwealth, by hospital type and by individual hospitals.

Healthcare-Associated Infections in Hospital Settings by Type: Number of Infections (Cases), Standardized Infection Ratio (SIR), and Number of Infections Needed to Prevent to Reach National SIR Goal (Goal) | Pennsylvania, 2021

Metric Acute Critical Access Children’s Long-Term Acute Psychiatric Inpatient Rehabilitation
CAUTI
Cases 1,396 11 15 54 1 102
SIR 0.89 (0.84, 0.94) 1.64 (0.86, 2.85) 0.92 (0.54, 1.49) 0.78 (0.59, 1.01) 0.39 (0.02, 1.92) 1.16 (0.95, 1.41)
Infections Needed to Prevent to Meet SIR Goal* (SIR=0.50) 611 8 7 19 Goal met 58
CLABSI
Cases 1,177 0 131 72 1 20
SIR 0.92 (0.87, 0.98) 0 (0.00, 2.43) 0.98 (0.82, 1.15) 0.57 (0.45, 0.72) 0.78 (0.49, 1.18)
Infections Needed to Prevent to Meet SIR Goal* (SIR=0.50) 540 Goal met 64 9 1* 7
COLO SSI
Cases 363 1 3 Not measured Not measured Not measured
SIR 0.84 (0.76, 0.93) 0.97 (0.05, 4.77) 0.79 (0.20, 2.14)
Infections Needed to Prevent to Meet SIR Goal* (SIR=0.70) 62 1* 1*
HYST SSI
Cases 62 0 Not measured Not measured Not measured Not measured
SIR 0.81 (0.63, 1.03)
Infections Needed to Prevent to Meet SIR Goal* (SIR=0.70) 8 Goal met
CDI LabID
Cases 2,221 Not measured Not measured 58 Not measured 161
SIR 0.57 (0.55, 0.60) 0.4 (0.31, 0.51) 0.59 (0.51, 0.69)
Infections Needed to Prevent to Meet SIR Goal* (SIR=0.70) Goal met Goal met Goal met
MRSA LabID
Cases 486 Not measured Not measured 10 Not measured 11
SIR 0.95 (0.86, 1.03) 0.39 (0.20, 0.70) 0.94 (0.49, 1.64)
Infections Needed to Prevent to Meet SIR Goal* (SIR=0.50) 229 Goal met 5
Goal*: The number of cases that needed to be prevented in order to meet the 2030 national or Pennsylvania SIR reduction goals. National goals were set by United States Department of Health and Human Services. Pennsylvania goals were set by the Department of Health.
1* - Number was more than zero and less than 1.0

2021 Catheter-associated urinary tract infections (CAUTIs): Among the 1,397,705 patient urinary catheter days, 1,579 CAUTIs were reported to NHSN from 279 Pennsylvania hospitals. The state SIR was 0.9, which was statistically significantly lower than the 2015 NHSN national baseline (95% CI:(0.86, 0.95)). The SIR in critical access hospitals was highest (SIR: 1.64; 95% CI: (0.86, 2.85)), and it was lowest in psychiatric hospitals (SIR: 0.39; 95% CI: (0.02, 1.92)). Thirteen hospitals had a SIR that was statistically significantly greater than 1.0. To meet the 2030 Pennsylvania Department HAI CAUTI goal of a 50% reduction in CAUTIs compared to those predicted in 2015 in the commonwealth, 703 additional infections needed to be prevented. The urinary catheter SUR was 0.86 (95% CI: (0.86, 0.86)) among 159 acute care hospitals. The SUR was highest among psychiatric hospitals (SUR: 1.18; 95% CI: (1.13, 1.24)).

2021 Central line-associated blood stream infections (CLABSIs): Among 1,504,306 patient central line days, 1,401 CLABSIs were reported to NHSN from 275 hospitals. The state SIR was 0.9, statistically significantly less than the 2015 national baseline (95% CI: (0.85, 0.94)). The SIR from acute care and long-term acute care hospitals reached statistical significance (SIR Acute: 0.92; 95% CI: (0.87, 0.98), SIR Long-term Acute: 0.57; 95% CI: (0.45, 0.72)). One psychiatric hospital reported a CLABSI when less than 1.0 was predicted. To meet the 2030 Health & Human Services (HHS) HAI CLABSI goal of a 50% reduction in cases compared with the number predicted in 2015 in the commonwealth, 620 additional infections needed to be prevented. Critical access and psychiatric hospitals reported using statistically significantly more central lines than predicted.

2021 Surgical site infections (SSI): In 2021, 163 Pennsylvania hospitals performed at least one of the seven surgical procedures tracked for SSI surveillance. Hospitals reported 103,860 of these surgical procedures and 832 (deep tissue or organ space) SSIs were later identified. Knee replacement surgery was the most common (N= 35,927) and represented 34.6% of all the surgical procedures. The SIR values for each surgery type were 1.26 (95% CI:(0.93, 1.68)) for cardiac surgeries, 1.0 (95% CI: (0.77, 1.28)) for cardiac bypass surgeries (CBG) with two incisions, 0.37 (95% CI: (0.09, 1.00)) for CBG with one incision, 0.84 (95% CI: (0.76, 0.93)) for colon surgeries (COLO), 1.08 (95% CI: (0.94, 1.24)) for hip replacement surgeries (HPRO), 0.81 (95% CI: (0.62, 1.03)) for abdominal hysterectomy surgeries (HYST), and 0.81 (95% CI: (0.67, 0.98)) for knee replacement surgeries (KPRO). Two hospitals had a statistically significant KPRO SIR value greater than 1.0. Three hospitals had a statistically significant SIR value greater than 1.0 for HPRO. Two hospitals had a statistically significant COLO SIR value greater than 1.0. One hospital had a statistically significant cardiac SIR value that was more than 1.0. Two hospitals had a statistically significant CGB with two incisions SIR value that was more than 1.0. Seven hospitals had a statistically significant COLO SIR value less than 1.0. One hospital had a statistically significant HPRO SIR value that was less than 1.0. Two hospitals had a statistically significant HYST SIR value that was less than 1.0. To meet the 2030 Pennsylvania Department COLO SSI goal of a 30% reduction in cases compared with the number predicted in 2015, 62 additional infections needed to be prevented. To meet the same 2030 Pennsylvania Department HYST goal in the commonwealth, 8 additional infections needed to be prevented.

2021 Clostridioides difficile infections (CDI LabID): Among the 7,709,646 patient days, 2,440 CDI LabID events were reported from 243 hospitals. CDI LabID events from children’s, critical access, and psychiatric hospitals were not required to be reported into NHSN. The state SIR was 0.57, statistically lower than predicted from the 2015 national baseline (95% CI: (0.55, 0.59)). The SIR values from ACUs, IRFs and LTACs were statistically significantly lower than predicted from the 2015 national baseline. The SIR from acute care hospitals was 0.57 (95% CI: (0.55, 0.60)). The SIR value from long-term acute care hospitals was 0.4 (95% CI: (0.31, 0.51)). The SIR value from inpatient rehabilitation facilities was 0.59 (95% CI: (0.51, 0.69)). Three hospitals had statistically significant SIR values greater than 1.0. The state met the 2030 Pennsylvania Department HAI CDI goal of a 30% reduction in cases compared with the number predicted in 2015.

2021 Methicillin-resistant Staphylococcus aureus Blood Infections (MRSA LabID): Among the 8,136,289 patient days, 507 MRSA LabID events were reported from 243 facilities. MRSA LabID events from children’s, critical access, and psychiatric hospitals are not required to be reported to NHSN. The state SIR was 0.92, and not statistically lower than predicted from the 2015 national baseline (95% CI: (0.84, 1.00)). The three hospital types reported fewer MRSA bloodstream events than predicted but only LTAC hospitals has a statistically significant SIR less than 1.0 (SIR 0.39 95% CI: (0.20, 0.70)). Four facilities had a statistically significant SIR value greater than 1.0. To meet the 2030 Pennsylvania Department MRSA LabID goal of a 50% reduction in cases compared with the number predicted in 2015, 232 MRSA LabID events needed to be prevented.

Although a thorough investigation has not been completed, it is noteworthy that the number of CAUTIs, CLABSIs, and MRSA blood infections increased by 275 (21.1%), 188 (15.5%), and 81 (19%), respectively, since 2020. The number of device and patient days increased between 8.8% and 11.3%. Hospitals reported 52 (2.1%) fewer CDI LabID events and 9.4% more CDI patient days in 2021 than in 2020.

There were 12.9% more COLO SSIs, 14.8% more HYST SSIs and 17.7% more HPRO SSIs in 2021 compared to 2020. There were 6% more COLO procedures and 2.2% more HPRO procedures performed in 2021 compared to 2020. There were 4.1% fewer HYST procedures performed in 2021 compared to 2020. There were six fewer KPRO SSIs in 2021 than in 2020 and the number of procedures increased by 4.8%. The number of cardiac SSIs increased from 28 in 2020 to 44 in 2021. The number of SSIs among patients who had CBG with one incision decreased from 9 in 2020 to 3 in 2021. This 2021 SIR (0.37) decreased considerably from the 2020 SIR (1.43). The number of SSIs among patients who had CBG with two incisions increased from 53 in 2020 to 59 in 2021. This 2021 SIR (1.0) was unchanged from the 2020 SIR (1.01).

According to CDC, each day, approximately one in 31 U.S. patients has at least one infection in association with his or her hospital care1. In Pennsylvania, this would equate to 47,169 people in 2021. The Pennsylvania Health Care Cost Containment Council reported that during 2021 there were 1,462,237 discharges from inpatient facilities2. While progress has been made since Pennsylvania began tracking HAIs, significant opportunities still exist for hospitals to prevent HAIs. A review article that evaluated the effectiveness of multifaceted interventions across different HAIs from 2005 - 2016 found that 54.3% of CAUTIs, 45.9% of CLABSIs and 46.1% of SSIs can be prevented3. The Department recommends that hospitals train staff and audit processes to ensure adherence to national guidelines, implement multifaceted interventions to prevent HAIs and perform surveillance to identify HAI clusters and outbreaks.