The European protocol for surveillance of
surgical site infections
Workshop “European surveillance of healthcare-associated infections: theory and practice”
Sofia, 26 – 27 November 2009
Outline
 Definition of surveillance
 Objectives of European surgical site infection (SSI)
surveillance
 Case definitions for SSIs
 Categories of surgical procedures under surveillance
 The National Healthcare Safety Network (NHSN) risk index
 Information to be collected
 Indicators of SSI incidence
Definition of surveillance
 Ongoing, systematic collection, analysis, and
interpretation of health data
 Closely integrated with the timely dissemination to
those who need to know
 Application of the data to preventing and controlling
disease
Thacker SB, Berkelman RL. Epidemiol Rev 1998
Why surveillance of SSIs?

At the level of the hospital
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Target infection control activity
Drive change in practice
Develop & underpin partnerships with clinical teams

At the regional/national level

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Follow up epidemiological trends in time
Identify and follow up risk factors of SSIs
Improve the quality of data collection

At the European level
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Work towards comparable surveillance methods
Describe and monitor the epidemiology of SSIs at European level
Draw up European reference tables for inter-hospital comparisons of
risk-adjusted SSI rates
Contribute to the extension of SSI surveillance in the European Union

General characteristics of European
SSI surveillance
 Patient-based surveillance
 Prospective surveillance
 Minimum period of three months recommended
 Participation on voluntary basis
Case definitions for SSIs
 To compare results must identify SSIs consistently
 May not capture every SSI
 European definitions based on CDC, USA, definitions
Widely adopted
International comparisons
European definitions of SSIs
 Superficial incisional
involves only skin or subcutaneous tissue
occurs within 30 days of surgery (with/without implant)
 Deep incisional
involves fascial or muscle layers
occurs within 30 days, implants within 1 year
A nonhuman-derived object, material,
or tissue (eg, hip prosthesis) that is
permanently placed in a patient
 Organ/space
part of anatomy opened / manipulated
infection appears related to surgery
occurs within 30 days, implants within 1 year
during an operative procedure and is
not routinely manipulated for
diagnostic or therapeutic purposes
Superficial Incisional SSI
 Must meet one of the following criteria:
 1. Purulent drainage from superficial incision
 2. Organisms isolated from a culture of:
fluid or tissue from superficial incision
 3. At least 1 sign or symptom of infection :
pain, tenderness, localised swelling, redness, heat
and
Incision deliberately opened by surgeon
 4. Clinicians diagnosis of superficial incisional
unless incision is
culture-negative
Deep Incisional SSI
 Must meet one of the following criteria:
 1. Purulent drainage from deep incision
 2. Deep incision spontaneously dehisces
or
Incision deliberately opened by surgeon in the
presence of at least 1 sign or symptom of infection:
unless incision is
culture-negative
fever (>38 C), pain, tenderness
 3. Abscess or other evidence of infection in deep
incision: direct examination or re-operation or histopathology or radiology
 4. Clinicians diagnosis of deep incisional
Organ/Space SSI
 Must meet one of the following criteria:
 1. Purulent drainage from a drain placed into the organ/space
 2. Organisms isolated from a culture of:
fluid or tissue in the organ/space
 3. Abscess or other evidence of infection involving the
organ/space: direct examination or re-operation or histopathology or radiology
 4. Clinicians diagnosis of organ/space SSI
Tips on applying the definitions of SSIs!
» Encourage medical and nursing staff to document clinical signs and
symptoms in notes and bacteriology request forms
» Develop clear guidance on when a wound swab should be taken:
there should be some signs or symptoms of infection
» Check significance of positive microbiology cultures with
microbiologist
» Visually check wounds if information from clinical staff/patients
notes is inconclusive
» If a patient is prescribed antibiotics do not assume these are for SSI
– check with clinician
Categories of surgical procedures under surveillance
NHSN1
category
Description
CBGB
Coronary artery bypass grafting with both chest and
36.10-36.14, 36.19
donor site incisions
Chest procedure to perform direct revascularisation of the
heart; includes obtaining suitable vein from donor site for
grafting
Coronary artery bypass grafting with chest incision only
36.15-36.17, 36.2
Chest procedure to perform direct vascularisation of the
heart using, e.g, the internal mammary artery
CBGC
CHOL
COLO
CSEC
HPRO
KPRO
LAM
1
Cholecystectomy
Removal of gallbladder; includes procedures performed
using the laparoscope
Colon surgery
Incision, resection or anastomosis of the large intestine;
includes large-to-small and small-to-large bowel
anastomosis
Caesarean section
Hip prosthesis
Arthroplasty of hip
Knee prosthesis
Arthroplasty of knee
Laminectomy
Exploration or decompression of spinal cord through
excision or incision into vertebral structure
National Healthcare Safety Network , USA
ICD-9-CM 2001 codes included in
the category
51.03, 51.04, 51.2-51.24
45.00, 45.03, 45.41, 45.49, 45.50, 45.52,
45.7-45.90, 45.92-45.95, 46.0, 46.03, 46.04,
46.1-46.14, 46.43, 46.52, 46.75, 46.76,
46.91, 46.92, 46.94, 48.5, 48.6-48.69
74.0-74.2, 74.4-74.99
81.51-81.53
81.54, 81.55
03.0-03.09, 80.50, 80.51, 80.59
How to compare SSI rates?
Case-mix adjustment needed
A possible approach
the National Healthcare Safety Network risk index
It is weighted by information on:
 Risk of contamination of the wound: wound contamination class
 Patient’s physical condition: American Society of Anaesthesiology
(ASA) physical status classification
 Duration of operation
How to build the NHSN risk index?
The wound contamination class
1. Clean:
uninfected operative wound and respiratory, alimentary, genital,
or urinary tract not entered; operative incisional wounds that follow nonpenetrating trauma should be included in this category, e.g. coronary artery
bypass graft
2. Clean-contaminated:
respiratory, alimentary, genital, or urinary tract entered, under controlled
condition and without unusual contamination, e.g. cholecystectomy
3. Contaminated:
open, fresh, accidental wound; operations with major breaks in sterile technique;
incisions in which acute, non purulent inflammation encountered, e.g. open bone
fracture just after the trauma
4. Dirty or infected wound:
old traumatic wound with retained devitalised tissue and wound that involves
existing clinical infection or perforated viscera, e.g. revision of infected hip prosthesis
How to build the NHSN risk index?
The physical status classification developed by the American
Society of Anaesthesiology (ASA score)
1.
2.
3.
4.
Normally healthy patient
Patient with mild systemic disease
Patient with severe systemic disease
Patient with incapacitating systemic disease that is a constant threat
to life
5. Moribund patient who is not expected to survive for 24 hours with
or without operation
How to build the NHSN risk index?
Duration of operation
Cut-off values for duration of operative
procedure categories
NHSN category
75th percentile cut-off value
in hours
CBGB
5
CBGC
4
CHOL
2
COLO
3
CSEC
1
HPRO
2
KPRO
2
LAM
2
In case of a reintervention within 72
hours after the primary operation,
the duration of reintervention need to
be added to the duration of the
primary operation
How to build the NHSN risk index?
Stratification points for the variables of the NHSN risk index
Variables for stratification
Wound classification
ASA score
Duration of operation
NHSN risk index
Stratification
points
Class > 2
1
>2
1
> 75th percentile
1
Four levels of risk are defined (levels 0 to 3)
using a combination of the three variables
Information to be collected
Surgical Site Infection Surveillance
Operative Procedure Data Collection Form
GENERAL DATA
Hospital Code
Operative Procedure ID
Age at Date of Operation (years)
Gender
Male |__|
|__|__|__|
Female |__|
d d
Unknown |__|
/ m m / y
y
y
y
Date of Admission
|_____|________|______________|
Date of Operation
|_____|________|______________|
Date of Discharge or
Date of Last FollowUp in Hospital
|_____|________|______________|
Date of Last FollowUp Post Discharge
|_____|________|______________|
Discharge Status
alive |__|
death |__|
NNIS Operation Code |__|__|__|__|
ICD-9-CM Operation Code
|__|__| |__|__|
Surgical Site Infection Surveillance
Operative Procedure Data Collection Form
STRATIFICATION AND PREOPERATIVE DATA
Endoscopic Procedure?
Yes |__| No |__|
ASA Physical Status Classification
Normal healthy patient 1 |__|
Wound Contamination Class
Mild systemic disease 2 |__|
Clean 1 |__|
Severe systemic disease 3 |__|
Clean-Contaminated 2 |__|
Incapacitating systemic disease 4 |__|
Contaminated 3 |__|
Moribund patient 5 |__|
Dirty/Infected 4 |__|
Duration of Operation – Minutes
(from skin incision to skin closure)
Urgent/Elective Operation
|__|__|__|
Were perioperative prophylactic antibiotics given?
Yes |__|
Urgent |__|
Elective |__|
No |__|
Surgical Site Infection Surveillance
Operative Procedure Data Collection Form
INFECTION DATA
Surgical Site Infection
Did the patient develop a surgical site infection?
Micro-Organism Code #1
No – Stop here |__|
|__|__|__|__|__|__|
Yes – Answer remaining questions |__|
Resistance Micro-Organism #1 |__|__|
Type of Surgical Site Infection
Micro-Organism Code #2
Superficial incisional |__|
|__|__|__|__|__|__|
Deep incisional |__|
Resistance Micro-Organism #2 |__|__|
Organ/Space |__|
Micro-Organism Code #3
Date of Infection
d d
/ m m / y
y
y
y
|_______|_______|______________|
|__|__|__|__|__|__|
Resistance Micro-Organism #3 |__|__|
How to measure the occurrence of SSIs?
For each surgical procedure category and for each level
of the NHSN risk index
three indicators
 Cumulative incidence
 Cumulative incidence, post-discharge surgical site infections
excluded
 Incidence density
Cumulative incidence of SSIs (1)
Definition
the crude percentage of operations resulting in a surgical site infection
How can be calculated
 Numerator: number of surgical site infections detected within 30
days after the operation or 1 year for hip prosthesis and knee
prosthesis
 Denominator: the total number of operations
Cumulative incidence of SSIs (2)
Example: cholecystectomy
6 months of surveillance 01.01.2008 – 30.06.2008
Number of SSIs detected within 30 days after the operation:
7
Total number of operations:
500
Cumulative incidence:
7 / 500 * 100 = 1.4%
Cumulative incidence of SSIs (3)
Interpretation
This indicator gives the most complete picture for a given surgical
procedure category
but
is highly dependent on the length of postoperative stay in hospital
and on the intensity of post-discharge surveillance
Cumulative incidence of SSIs,
post-discharge SSIs excluded (1)
Definition
the crude percentage of operations resulting in a surgical site infection,
before hospital discharge
How can be calculated
 Numerator: number of surgical site infections detected before
hospital discharge
 Denominator: the number of operations with known date of hospital
discharge
Cumulative incidence of SSIs,
post-discharge SSIs excluded (2)
Example: cholecystectomy
6 months of surveillance 01.01.2008 – 30.06.2008
Number of SSIs detected before hospital discharge:
3
Number of operations with known date of hospital discharge: 400
Cumulative incidence of SSIs, post-discharge SSIs
excluded:
3 / 400 * 100 = 0.8%
Cumulative incidence of SSIs,
post-discharge SSIs excluded (3)
Interpretation
This indicator only considers surgical site infections detected in the
hospital, therefore is independent of post-discharge surveillance
Anyway it depends on the length of postoperative stay in hospital
Incidence density of SSIs (1)
Definition
The rate of surgical site infections detected before hospital discharge
standardized by the length of patient’s postoperative stay in hospital
It can only be calculated when the discharge date is known
How can be calculated
 Numerator: number of surgical site infections detected before
hospital discharge
 Denominator: the total number of postoperative patient-days in
hospital (sum of length of postoperative stay in hospital for patients
with known date of hospital discharge)
Incidence density of SSIs (2)
Example: cholecystectomy
6 months of surveillance 01.01.2008 – 30.06.2008
Number of SSIs detected before hospital discharge:
Total number of postoperative patient-days in hospital:
3
2,000
Incidence density of SSIs:
3 / 2,000 * 1,000 = 1.5/1,000 patient-days
Incidence density of SSIs (3)
Interpretation
This indicator only considers surgical site infections detected in the
hospital and therefore it does not reflect the complete epidemiological
picture
However, it is independent of post-discharge surveillance and corrects
for differences in postoperative hospital stay
Therefore this indicator may be more reliable for inter-hospital or
inter-network comparisons
Conclusions
 The European protocol of SSI surveillance is a consolidated
tool for SSI surveillance at European level; since the early
2000 it has been used by 14 European countries
 It allows to develop a “common methodological language”
between different countries and different networks
 It contributes to get SSI incidence indicators in order to
monitor epidemiological trends and to analyse inter-country
and inter-hospital differences
Thank you and Good luck
www.ecdc.europa.eu| info@ecdc.europa.eu
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