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 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

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 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

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: 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

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 ICD-9-CM 2001 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 36.10-36.14, 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 36.15-36.17, 36.2 CHOL Cholecystectomy Removal of gallbladder; includes procedures performed using the laparoscope 51.03, 51.04, 51.2-51.24 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, 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 CSEC Caesarean section 74.0-74.2, 74.4-74.99 HPRO Hip prosthesis Arthroplasty of hip 81.51-81.53 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 03.0-03.09, 80.50, 80.51, 80.59 1 National Healthcare Safety Network , USA

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 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

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

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

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

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 |__| 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

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 |__|

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: 3 Total number of postoperative patient-days in hospital: 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

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