SURGICAL SITEINFECTIONS:
SURVEILLANCE & PREVENTION
Disclosures:
• I have
– No conflicts of interest
– No commercial support
– No specific product will be endorsed during this presentation
Facts
• In 2002, in the United States, an estimated 14 million NHSN operative procedures were performed (CDC unpublished data).
• Among the “big four” healthcare-associated infections (i.e. PNEU, SSI, UTI, BSI) SSIs were the second most common healthcare-associated infection, accounting for 17% of all HAIs among hospitalized patients
• A similar rate was obtained from NHSN hospitals reporting data in 2006-2008 (15,862 SSI following 830,748 operative procedures) (CDC, unpublished data) with an overall rate of nearly 2%.
Facts
• While advances have been made in infection control practices, including improved operating room ventilation, sterilization methods, barriers, surgical technique, and availability of antimicrobial prophylaxis, SSIs remain a substantial cause of morbidity and mortality among hospitalized patients.
• In one study, among nearly 100,000 HAIs reported in one year, deaths were associated with SSIs in more than 8,000 cases.
Surveillance
• Surveillance of SSI with feedback of appropriate data to surgeons has been shown to be an important component of strategies to reduce SSI risk.
• A successful surveillance program includes the use of epidemiologically sound infection definitions and effective surveillance methods,
* stratification of SSI rates according to risk factors associated with SSI development, and
* data feedback.
• Recommendations are outlined in the CDC’s Guideline for Prevention of Surgical Site Infection, 1999.
Sources of Data for Finding SSI
• Microbiology reports• Infection control rounds on nursing units• Pharmacy reports for antimicrobial use• Temperature chart• Operating room report of surgeries• Use post-discharge surveillance methods for
SSI• Electronic Surveillance Programs• ER Diagnosis List• Case Managers
CDC Definitions
• NHSN manual http://www.cdc.gov/nhsn/PDFs/pscManual/9pscSSIcurrent.pdf
• Read the “fine print”
• 3 Types– Superficial Incisional SSI
– Deep Incisional SSI
– Organ/ Organ Space
NHSN Operative Procedure
• Occurs on Inpatient or Outpatient
• Takes place in an operating room– Meets AIA criteria
• OR, C-Section room, Interventional radiology room, cardiac cath lab
• takes place during an operation (defined as a single trip to the OR where a surgeon makes at least one incision through the skin or mucous membrane, including laparoscopic approach, and closes the incision before the patient leaves the OR
• Included in Table 1
CDC Definitions• Superficial (Primary or Secondary)
– Infection occurs within 30 days after operative procedureAnd– Infection involves only skin or subq tissue of the incision And at least one of the following:
• Purulent drainage from superficial incision• Positive culture from aseptically obtained specimen• One: Pain, tenderness, localized swelling, redness, heat and
superficial incision deliberately opened by surgeon and is culture positive or not cultured
• Diagnosis of Superficial Incisional SSI by surgeon or attending physician Or other designee **
(The term attending physician for the purposes of application of the NHSN SSI criteria may be interpreted to mean the surgeon, infectious disease, other physician on the case, emergency physician or physician’s designee (nurse practioner or physician’s assistant)
Exclusions• Stitch Abscess
• Localized stab wound infection or pin site infection
• “Cellulitis” by itself
• Circumcision infection
• Burn wound
• Episiotomy (Not a NHSN operative procedure)
CDC Definitions
• Deep Incisional SSI– Infection occurs within 30 or 90 days after the
operative procedure according to the list in Table 12
AND
– Infection involves deep soft tissues of incision
And at least one of the following
• Purulent drainage from superficial incision
• Organisms isolated from an aseptically obtained culture of fluid or tissue form the superficial incision
• Spontaneously dehisces or is deliberately opened by surgeon when one of S/S: fever, localized
pain, tenderness, unless site culture negative and is either
culture positive or not cultured
• Abscess or other evidence of infection identified by one of
multiple ways
Code Operative Procedure Code Operative Procedure
AAA Abdominal aortic aneurysm repair
LAM Laminectomy
AMP Limb amputation LTP Liver Transplant
APPY Appendix surgery NECK Neck Surgery
AVSD Shunt for Dialysis NEPH Kidney Surgery
BILI Bile Duct, liver or pancreatic surgery
OVRY Ovarian Surgery
CEA Carotid Endarterectomy PRST Prostate Surgery
CHOL Gallbladder surgery REC Rectal Surgery
COLO Colon Surgery SB Small bowel Surgery
CSEC Cesarean Section SPLE Spleen Surgery
GAST Gastric Surgery THOR Thoracic Surgery
HTP Heart Transplant THYR Thyroid and/or parathyroid
HYST Abdominal Hysterectomy VHYS Vaginal Hysterectomy
KTP Kidney Transplant XLAP Exploratory Laparotomy
OTH Other operative procedure not included in the NHSN categories
30-Day Surveillance
Code Operative Procedure
BRST Breast Surgery
CARD Cardiac Surgery
CBGB Oronary artery bypass graft with both chest and donor site incisions
CBGC Coronary artery bypass graft with chest incision only
CRAN Craniotomy
FUSN Spinal Fusion
FX Open reduction of fracture
HER Herniorrhaphy
HPRO Hip Prosthesis
KPRO Knee Prosthesis
PACE Pacemaker Surgery
PVBY Peripheral vascular bypass surgery
RFUSN Refusion of spine
VSHN Ventricular Shunt
90-Day Surveillance
CDC Definitions• Organ / Space SSI
– Infection occurs within 30 or 90 days after the operative procedure according to the list in Table 12
AND– infection involves any part of the body, excluding the skin incision, fascia, or muscle layers, that is opened or manipulated during the operative procedure
AND at least one of following:
– Purulent drainage from a drain – Organisms isolated from an aseptically-obtained culture of fluid
or tissue in the organ/space– Abscess or other evidence of infection involving the
organ/space that is detected on direct examination, during invasive procedure, or by histopathologic examination or imaging test
AND
• Meets at least one criterion for a specific organ/space infection site listed in Table 13
Code Site Code Site
BONE Osteomyelitis LUNG Other infections of the respiratory tract
BRST Breast abscess or mastitis MED Mediastinitis
CARD Myocarditis or pericarditis MEN Meningitis or ventriculitis
DISC Disc space ORAL Oral cavity (mouth, tongue, or gums)
EAR Ear, mastoid OREP Other infections of the male or female
reproductive tract
EMET Endometritis OUTI Other infections of the urinary tract
ENDO Endocarditis SA Spinal abscess without meningitis
EYE Eye, other than conjunctivitis SINU Sinusitis
GIT GI tract UR Upper respiratory tract
IAB Intraabdominal, not specified else -
where
VASC Arterial or venous infection
IC Intracranial, brain abscess or dura
VCUF Vaginal cuff
JNT Joint or bursa
PJI Periprosthetic Joint Infection
Table 13 – Organ Space Criteria
Risk Stratification
• ASA score (American Society of
Anesthesiologists)
• Wound Class
• T time or cut time
ASA ScoreAmerican Society of Anesthesiologists
ASA score Physical Status
1 Completely healthy pt
2 Pt w/ mild systemic disease
3 Pt w/ severe systemic disease, not
incapacitating
4 Incapacitating disease that is constant
threat to life
5 Moribund pt not expected to live >24 hrs
w/or w/o surgery
6 Declared brain-dead
E Emergency case
Wound ClassHICPAC Guideline for Prevention of SSI
Classification Description
Class I
Clean
An uninfected operative wnd in which no inflammation is
encountered & the respiratory, alimentary, genital or
uninfected urinary tract is not entered. In addition, clean
wnds are primarily closed & if necessary, drained with
closed drainage. Operative incisional wnds that follow
nonpenetrating (blunt) trauma should be included in this
category if they meet the criteria.
Class II
Clean-
contaminated
An operative wnd in which the respiratory, alimentary,
genital or urinary tracts are entered under controlled
conditions and without unusual contamination.
Specifically, operations involving the biliary tract,
appendix, vagina and oropharynx are included in this
category, provided no evidence of infection or major
break in technique is encountered.
Wound ClassHICPAC Guideline for Prevention of SSI
Classification Description
Class III
Contaminated
Open, fresh, accidental wnds. In addition, operation with
major breaks in sterile technique (e.g., open cardiac
massage) or gross spillage from the gastrointestinal tract,
and incisions in which acute, nonpurulent inflammation is
encountered are included in this category.
Class IV
Dirty-Infected
Old traumatic wnds with retained devitalized tissue and
those that involve existing clinical infection or perforated
viscera. This definition suggests that the organisms
causing postoperative infection were present in the
operative field before the operation
T Time or Cut Time
Time period from when surgeonfirst starts to make the incision to the
last suture.
• If more than one NHSN operative procedure is done through the same incision during the same trip to the OR, each procedure T time should be the two times added together.
• Other rules for multiple or consecutive procedures. See NHSN Patient Safety Component Manual.
Risk Index Calculated
0 Points 1 Point
ASA 1 and 2 3 and >
Wound Class 1 and 2 3 and 4
Cut Time ≤ RT ≥ RT
RT = Recommended time or Duration Cut Point which is the 75th
percentile of duration times of these procedures.
Examples of Risk Index Statification
Surgery ASA Wnd Cls T Time R Index
HERN 2 II < 1 hr RI = 0
CHOLE 3 II < 1 hr RI = 1
THR 3 II > 2 hr RI = 2
APPY 3 III > 2 hr RI = 3
Probability of Wound Infection
Wound
Class
RI 0 RI 1 RI 2
Clean
I
1.0 % 2.3 % 5.4 %
Clean cont.
II
2.1 % 4.0 % 9.5 %
Contam
III
3.4 % 6.8 % 13.2 %
How to Compare Rates
• Benchmark against your own hospital by month, quarter or year
• Benchmark against the hospitals within
your own system
• Benchmark against NHSN (National
Healthcare Safety Network)
Your SSI Rate
• Numerator = # of SSIs
• Denominator = # of surgery cases of that particular procedure for that particular Risk Index.
• Date of SSI is the date of the procedure, not the date the SSI is discovered.
Your SSI Rate
Example:
1 hysterectomy SSI in RI 0, 82 cases
3 hysterectomy SSIs in RI 1, 29 cases
1 hysterectomy SSI in RI 2 or 3, 24 casesYour Rate
RI 0 RI 1 RI 2
1 = 1.22 82
3 = 10.34 29
1 = 4.17 24
Lumped together: 5 = 3.70 135
NHSN System Report
• AJIC (Am J Infect Control 2009;37:783-805)
http://www.cdc.gov/nhsn/PDFs/dataStat/2009NHSNReport.pdf
Comparing Your Rates
Your Rate:
Risk 0 Risk 1 Risk 2,3
1 = 1.22 82
3 = 10.34 29
1 = 4.17 24
NHSN Rates
Risk 0 Risk 1 Risk 2,3
Mean
1.12 2.41 4.37
Median
0.70 1.88 3.13
Introducing SIR(Standardized Infection Ratio)
The SSI SIR is the result of logistic regression modeling that considered all procedure-level data collected by NHSN facilities in order to provide better risk adjustment than afforded by the risk index.
Standardized infection ratio (sir)
• Driven by need for a summary measure (replacing multiple rate comparisons)
SIR calculations added to NHSN Oct 2010
• SIR adjusts for differences in levels of infection risk in your patients (e.g. by unit type for CLABSI)
• Not only does this allow for all available risk factors to be considered, but it also allows for the risk factors to be procedure-specific
• SIR compares # of HAIs reported by your hospital with the “predicted” # based on NHSN data
NHSN data (2006-08) used for national predicted
values
• SIR value of 1.0 means your hospital is observing HAIs as national data predict (i.e. not different)
• Old Way: Used a 0-3 Risk Index to stratify patient risk for all procedures◊ Based on ASA, Wound class, Duration >75th percentile
• New Way: Adjusts for individual patient risk using only those variables found to be associated with SSI risk for each procedure type (determined by logistic regression models)
Example: SSI risk factors for HPROAge, Anesthesia type, ASA score, surgical duration, HPRO type, Medical School affiliation, number of beds, trauma status
How is this different from the current SSI SIRs in NHSN?
The SIR or Standardized Infection Ratio is a number that comparesthe number of HAIs that occur in a facility to a predicted number of infections (based on the US data and adjusted for several risk factors).
The intercept represents underlying infection risk when none of the risk factors in the model are present
Factors in this model that add to SSI risk are;◊ Age equal to or younger than 44 years◊ ASA score of 3, 4, or 5◊ Duration of surgery longer than 100 minutes
(incision to close time)◊ Procedure done at hospital affiliated with a medical
school (from Annual Facility Survey)
Interpreting the SSI sir
Ok… so let’s work through some examples:
What is the SIR interpretation if:
•P-value = 0.001 and SIR = 1.12
The p-value shows significance and the SIR is
greater than 1, so it is “Worse than the
national experience”
•P-value = 0.1 and SIR = 0.59
The p-value is NOT significant so the
interpretation is “About the same as the
national experience”
•P-value = 0.04 and SIR = 0.90 The p-value is less than 0.05, so it is
significant and the SIR is less than 1
so it is “Better than the national
experience”
•P-value = 0.3 and SIR = 4.0 Here the p-value is greater than 0.05 and
therefore not significant. Any time the
p-value is greater than 0.05, the interpretation will be “About the same as
the national experience”regardless of what
the SIR value is.
What is the SIR interpretation if:
•Predicted number of Infections = 0.76
Because the predicted number of infections
is less than 1, NHSN will not calculate a SIR
and therefore the interpretation is that
there is not enough data to calculate a
difference.
What is the SIR interpretation if:
So… as previously stated;
• If the SIR is > 1, a facility is worse than the national experience.
• If the SIR is < 1, a facility is better than the national experience.
• The p-value determines whether the SIR is significantly different from the national experience. If it does not indicate significance (by being greater than 0.05), then the facility is about the same as the national experience.
• SIR will only be calculated for your hospital if the expected number of HAIs is >1(because can’t have less than a whole person infected!)
http://www.cdc.gov/nhsn/PDFs/Newsletters/NHSN_NL_OCT_2010SE_final.pdf
SIR
Getting it Right!Learning How to Use the NHSN
Surveillance Definitions
Teresa C. Horan, MPHDivision of Healthcare Quality Promotion
Centers for Disease Control and Prevention
files.abstractsonline.com/CTRL/2a/7/340/e8f/409/418/.../a143_1.pdf
Case 1
• 45 year-old male patient had colon resection (COLO) performed on 6/18
• 6/22:– The upper aspect of the patient’s abdominal wound has
purulent drainage with some redness and induration
– Wound swabs sent to lab for culture
– Patient started on antibiotics
• 6/24: – Wound culture grew Enterobacter spp. and E. coli
Does this patient have an HAI?
CDC Definitions• Superficial (Primary or Secondary)
– Infection occurs within 30 days after operative procedureAnd– Infection involves only skin or subq tissue of the incision And at least one of the following:
• Purulent drainage from superficial incision• Positive culture from aseptically obtained specimen• One: Pain, tenderness, localized swelling, redness, heat and
superficial incision deliberately opened by surgeon and is culture positive or not cultured
• Diagnosis of Superficial Incisional SSI by surgeon or attending physician Or other designee **
(The term attending physician for the purposes of application of the NHSN SSI criteria may be interpreted to mean the surgeon, infectious disease, other physician on the case, emergency physician or physician’s designee (nurse practioner or physician’s assistant)
Case 2• Patient is admitted to the hospital on
4/12 for elective surgery and an MRSA screening test is positive.
• On the same day, patient undergoes colon surgery (COLO).
• On 4/16, a deep incisional SSI is identified, and is culture positive for MRSA. Is this infection considered healthcare-associated?
Case 3
• Which of the following does not meet the criteria for superficial incisional SSI if identified within 30 days after the procedure?
A. Physician documents “superficial wound infection”
B. Purulent drainage noted from subcutaneous tissue of the incision
C. Physician documents “cellulitis”
D. MRSA grows from an aseptically obtained swab of the superficial incision
Case 4
• Patient had a spinal fusion (FUSN) performed
• Increased back pain
• MRI revealed abscess in the spinal epidural space
• Surgeon opened wound & drained abscess; specimen to lab for culture
• Culture positive for Pseudomonas aeruginosa
Does this patient have an HAI?
CDC Definitions• Organ / Space SSI
– Infection occurs within 30 or 90 days after the operative procedure according to the list in Table 12
AND– infection involves any part of the body, excluding the skin incision, fascia, or muscle layers, that is opened or manipulated during the operative procedure
AND at least one of following:
– Purulent drainage from a drain – Organisms isolated from an aseptically-obtained culture of fluid
or tissue in the organ/space– Abscess or other evidence of infection involving the
organ/space that is detected on direct examination, during invasive procedure, or by histopathologic examination or imaging test
AND
• Meets at least one criterion for a specific organ/space infection site listed in Table 13
Code Site Code Site
BONE Osteomyelitis LUNG Other infections of the respiratory tract
BRST Breast abscess or mastitis MED Mediastinitis
CARD Myocarditis or pericarditis MEN Meningitis or ventriculitis
DISC Disc space ORAL Oral cavity (mouth, tongue, or gums)
EAR Ear, mastoid OREP Other infections of the male or female
reproductive tract
EMET Endometritis OUTI Other infections of the urinary tract
ENDO Endocarditis SA Spinal abscess without meningitis
EYE Eye, other than conjunctivitis SINU Sinusitis
GIT GI tract UR Upper respiratory tract
IAB Intraabdominal, not specified else -
where
VASC Arterial or venous infection
IC Intracranial, brain abscess or dura
VCUF Vaginal cuff
JNT Joint or bursa
PJI Periprosthetic Joint Infection
Table 13 – Organ Space Criteria
Case 5
If a superficial incisional chest site
infection becomes evident 34 days
after CABG in which sternal wires were
used, is an SSI reported?
Questions?…