1. The European protocol for surveillance of surgical site infections
Workshop “European surveillance of healthcare-associated infections: theory and practice”
Sofia, 26 – 27 November 2009

2. 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

3. 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

4. Why surveillance of SSIs?
At the level of the hospital
Target infection control activity
Drive change in practice
Develop & underpin partnerships with clinical teams
At the regional/national level
Follow up epidemiological trends in time
Identify and follow up risk factors of SSIs
Improve the quality of data collection
At the European level
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

5. General characteristics of European SSI surveillance
Patient-based surveillance
Prospective surveillance
Minimum period of three months recommended
Participation on voluntary basis

6. 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

7. 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
Organ/space
part of anatomy opened / manipulated
infection appears related to surgery
A nonhuman-derived object, material, or tissue (eg, hip prosthesis) that is permanently placed in a patient during an operative procedure and is not routinely manipulated for diagnostic or therapeutic purposes

9. 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

10. 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:
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
unless incision is culture-negative

11. 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

12. 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

13. Categories of surgical procedures under surveillance
NHSN1 category
Description
ICD-9-CM codes included in the category
CBGB
Coronary artery bypass grafting with both chest and donor site incisions
Chest procedure to perform direct revascularisation of the heart; includes obtaining suitable vein from donor site for grafting
, 36.19
CBGC
Coronary artery bypass grafting with chest incision only
Chest procedure to perform direct vascularisation of the heart using, e.g, the internal mammary artery
, 36.2
CHOL
Cholecystectomy
Removal of gallbladder; includes procedures performed using the laparoscope
51.03, 51.04,
COLO
Colon surgery
Incision, resection or anastomosis of the large intestine; includes large-to-small and small-to-large bowel anastomosis
45.00, 45.03, 45.41, 45.49, 45.50, 45.52, , , 46.0, 46.03, 46.04, , 46.43, 46.52, 46.75, 46.76, , 46.92, 46.94, 48.5,
CSEC
Caesarean section ,
HPRO
Hip prosthesis
Arthroplasty of hip
KPRO
Knee prosthesis
Arthroplasty of knee
81.54, 81.55
LAM
Laminectomy
Exploration or decompression of spinal cord through excision or incision into vertebral structure
, 80.50, 80.51, 80.59
1 National Healthcare Safety Network , USA

14. 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

15. How to build the NHSN risk index?
The wound contamination class
Clean:
uninfected operative wound and respiratory, alimentary, genital,
or urinary tract not entered; operative incisional wounds that follow non-
penetrating trauma should be included in this category, e.g. coronary artery
bypass graft
Clean-contaminated:
respiratory, alimentary, genital, or urinary tract entered, under controlled
condition and without unusual contamination, e.g. cholecystectomy
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
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

16. How to build the NHSN risk index?
The physical status classification developed by the American Society of Anaesthesiology (ASA score)
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
Moribund patient who is not expected to survive for 24 hours with or without operation

17. 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
KPRO
LAM
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

18. How to build the NHSN risk index?
Stratification points for the variables of the NHSN risk index
Variables for stratification
NHSN risk index
Stratification points
Wound classification
Class > 2 1
ASA score
> 2
Duration of operation
> 75th percentile
Four levels of risk are defined (levels 0 to 3) using a combination of the three variables

19. Information to be collected

20. 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 |__| Unknown |__|
d d / m m / y y y y
Date of Admission |_____|________|______________| Discharge Status alive |__|
death |__|
Date of Operation |_____|________|______________|
NNIS Operation Code |__|__|__|__|
Date of Discharge or |_____|________|______________|
Date of Last Follow-
Up in Hospital ICD-9-CM Operation Code
|__|__| |__|__|
Date of Last Follow |_____|________|______________|
Up Post Discharge

21. 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 |__|__|__| Were perioperative prophylactic antibiotics given?
(from skin incision to skin closure)
Yes |__| No |__|
Urgent/Elective Operation
Urgent |__|
Elective |__|

22. 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 |__|__|

23. 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

24. 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

25. Cumulative incidence of SSIs (2)
Example: cholecystectomy
6 months of surveillance –
Number of SSIs detected within 30 days after the operation: 7
Total number of operations:
Cumulative incidence: / 500 * 100 = 1.4%

26. 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

27. 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

28. Cumulative incidence of SSIs, post-discharge SSIs excluded (2)
Example: cholecystectomy
6 months of surveillance –
Number of SSIs detected before hospital discharge:
Number of operations with known date of hospital discharge: 400
Cumulative incidence of SSIs, post-discharge SSIs
excluded: / 400 * 100 = 0.8%

29. 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

30. 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)

31. Incidence density of SSIs (2)
Example: cholecystectomy
6 months of surveillance –
Number of SSIs detected before hospital discharge:
Total number of postoperative patient-days in hospital: ,000
Incidence density of SSIs:
3 / 2,000 * 1,000 = 1.5/1,000 patient-days

32. 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

33. 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

34. Thank you and Good luck