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• In 2002, in the United States, an estimated 14 million NHSN operative procedures were performed (CDC unpublished data).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was obtained from NHSN hospitals reporting data in 2006-2008 (15,862 SSI following 830,748 operative procedures) (CDC, unpublished data) with an overall rate of nearly 2%.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?…