Prevention of Surgical Site Infections: Considerations in Measuring Effectiveness Michele L. Pearson, MD Division of Healthcare Quality Promotion National Center for Infectious Diseases

Objectives Provide overview of epidemiology of surgical site infections (SSI) Discuss SSI prevention strategies Highlight current surveillance systems for SSI Provide overview of HICPAC/CDC process for developing recommendations for prevention healthcare-associated infections

Public Health Importance of Surgical Site Infections In U.S., >40 million inpatient surgical procedures each year; 2-5% complicated by surgical site infection SSIs second most common nosocomial infection (24% of all nosocomial infections) Prolong hospital stay by 7.4 days Cost $400-$2,600 per infection (TOTAL: $130-$845 million/year)

CDC Definition of Surgical Site Infections SSI level classification Incisional SSI - Superficial incisional = skin and subcutaneous tissue - Deep incisional = involving deeper soft tissue Organ/Space SSI - Involve any part of the anatomy (organs and spaces), other than the incision, opened or manipulated during operations

Cross Section of Abdominal Wall Depicting CDC SSI Classifications

Source of SSI Pathogens Endogenous flora of the patient Operating theater environment Hospital personnel (MDs/RNs/staff) Seeding of the operative site from distant focus of infection (prosthetic device, implants)

Microbiology of SSIs 1986-1989 (N=16,727) 1990-1996 (N=17,671) Staphylococcus aureus 17% Coagulase neg. staphylococci 12% Escherichia coli 10% Enterococcus spp. 8% Pseudomonas aeruginosa Staphylococcus aureus 20% Coagulase neg. staphylococci 14% Escherichia coli 8% Enterococcus spp. 12% Pseudomonas aeruginosa

Microbiology of SSIs Unusual pathogens • Rhizopus oryzea - elastoplast adhesive bandage • Clostridium perfringens - elastic bandages • Rhodococcus bronchialis - colonized health care personnel • Legionella dumoffii and pneumophila - tap water • Pseudomonas multivorans - disinfectant solution Cluster of unusual SSI pathogens  formal epidemiologic investigation

Pathogenesis of SSI Relationship equation Dose of bacterial contamination x Virulence Resistance of host SSI Risk

SSI Risk Factors Age Obesity Diabetes Malnutrition Prolonged preoperative stay Infection at remote site Systemic steroid use Nicotine use Hair removal/Shaving Duration of surgery Surgical technique Presence of drains Inappropriate use of antimicrobial prophylaxis

Perioperative Preventive Measures

Role of Antimicrobial Prophylaxis (AP) in Preventing SSI Refers to very brief course of an antimicrobial agent initiated just before the operation begins Should be viewed as an adjunctive preventive measure Appropriately administered AP associated with a 5-fold decrease in SSI rates

Importance of Timing of Surgical Antimicrobial Prophylaxis (AP) Prospective study of 2,847 elective clean and clean-contaminated procedures Early AP (2-24 hrs before incision): 3.8% Postop AP (3-24 hrs after incision): 3.3% Periop AP (< 3 hrs after incision): 1.4% Preop AP (<2 hrs before incision): 0.6% Classen, 1992 (NEJM 326:281-286)

Impact of Prolonged Surgical Prophylaxis DESIGN: Prospective POPULATION: CABG patients (N=2641) Group 1: pts who received < 48 hours of AP Group 2: pts who received > 48 hrs of AP

Impact of Prolonged Surgical AP OUTCOMES • Incidence of SSI • Isolation of a resistant pathogen RESULTS: 43% of patients received AP > 48 hr SSI Incidence • <48 hrs group: 8.7% (131/1502) vs • >48 hrs group: 8.8% (100/1139), p=1.0 Antimicrobial resistant pathogen • OR 1.6 (95% CI 1.1-2.6)

Enhanced Perioperative Glucose Control in Diabetic Patients DESIGN: Prospective, sequential study POPULATION: Diabetic patients undergoing cardiac surgery (N=2467) during 1987-1997 Controls: pts who received intermittent subQ insulin (SQI) Treated: pts who received continuous intravenous (IV) insulin Furnary AP; Ann Thorac Surg, 2000

Enhanced Perioperative Glucose Control in Diabetic Patients OUTCOMES • Blood glucose <200 mg/dl in first two days postop • Incidence of deep sternal SSI RESULTS • SQI group: 2.0% (19/968) vs • IVI group: 0.8% (12/1499), p=0.01 Furnary AP; Ann Thorac Surg, 2000

Supplemental Perioperative O2 DESIGN: Randomized controlled trial, double blind POPULATION: Colorectal surgery (N=500) INTERVENTION: 30% vs 80% inspired oxygen during and up to hours after surgery RESULTS: SSI incidence 5.2% (80% O2) vs 11.2% (30% O2), p=0.01 Greif, R, et al , NEJM, 2000

Pre-operative Antiseptic Showers/Baths Most studies examine effects on skin colony counts antiseptic showering decreases colony counts Few studies examine effect on SSI rates No Shower Shower Cruse, 1973 2.3% 1.3% Ayliffe, 1983 4.9% 5.4% Rooter, 1988 2.4% 2.6%

Pre-operative Shaving/Hair Removal Seropian, 1971 Method of hair removal Razor = 5.6% SSI rates Depilatory = 0.6% SSI rates No hair removal = 0.6% SSI rates Timing of hair removal Shaving immediately before = 3.1% SSI rates Shaving  24 hours before = 7.1% SSI rates Shaving >24 hours before = 20% SSI rates

CENTERS FOR DISEASE CONTROL Pre-operative Shaving/Hair Removal Multiple studies show - Clipping immediately before operation associated with lower SSI risk than shaving or clipping the night before operation CENTERS FOR DISEASE CONTROL AND PREVENTION

Surgical Attire Scrub suits Cap/hoods Shoe covers Masks Gloves Gowns

Surgical Technique Removing devitalized tissue Maintaining effective hemostasis Gently handling tissues Eradicating dead space Avoiding inadvertent entries into a viscus Using drains and suture material appropriately

Parameters for Operating Room Ventilation* Temperature: 68o-73oF, depending on normal ambient temp Relative humidity: 30%-60% Air movement: from “clean to less clean” areas Air changes: >15 total per hour >3 outdoor air per hour *American Institute of Architects, 1996

Role of Laminar Air Flow (Ultraclean Air) in Preventing SSI Most studies involve only orthopedic operations Lidwell et al: 8,000 total hip and knee replacements ultraclean air: SSI rate 3.4% to 1.6% antimicrobial prophylaxis (AP): SSI rate 3.4% to 0.8% ultraclean air + AP: SSI rate 3.4% to 0.7%

Status of SSI Surveillance

CDC Surveillance Systems NNIS DSN NaSH Nosocomial infections in critical care and surgical patients Bloodstream and vascular access infections in dialysis outpatients Exposure to bloodborne pathogens; TB skin testing and exposure; Vaccine: history, receipt, and adverse events 1970-2004 1999-2004 1996-present

Characteristics of NNIS Hospitals, 2000 58% are MAJOR TEACHING 10% are Graduate Teaching 15% are Limited Teaching 16% are Non Affiliated Hospitals Bed Size Median: 360 beds No facilities < 100 beds

Variables Collected in Surgical Patient Component, NNIS Age Sex ASA score Wound class Trauma-related Type of anesthesia Emergency vs elective Duration of surgery Length of postoperative stay Infection site (skin/soft tissue, organ space) Pathogen Mortality Hospital demographics (bed-size, affiliation)

SSI Risk Index From the U.S. National Nosocomial Infections Surveillance (NNIS) system American Society of Anesthesiologists (ASA) score 1 to 5, from 1=“normal, healthy” to 5=“patient not expected to survive for 24 hours with OR without operation Wound Class Clean, clean-contaminated, contaminated, dirty Duration of surgery

Surgical Site Infection (SSI) Rates By Risk Category, NNIS System, 1986-1999 16 12 Low risk Medium SSIs per 100 operations 8 low risk Medium high risk 4 High risk 1992 1993 1994 1995 1996 1997 1998 1999 1986-90 Years

SSI Definitions: Period of Surveillance Infection occurs within 30 days after the operative procedure if no implant is left in place or within 1 year if implant is in place and the infection appears to be related to the operative procedure

Challenges to Surveillance for SSIs Admissions Patient-days Length of Stay Inpatient Surgical Procedures Nosocomial Infection Rate per 1,000 Patient-days 1975 37,700,000 299,000,000 7.9 days 18,300,000 7.2 1995 35,900,000 190,000,000 5.3 days 13,300,000 9.8 Change 5% 36% 33% 27% 36% CENTERS FOR DISEASE CONTROL AND PREVENTION

Integration of CDC’s three patient and healthcare personnel What Is NHSN? Integration of CDC’s three patient and healthcare personnel surveillance systems NNIS NaSH DSN

NHSN Premises Maintain the goals of predecessor systems Minimize data collection and manual data entry burden Streamline existing surveillance protocols Increase capacity for capturing electronic data (e.g., Laboratory information systems, operating room, pharmacy, clinical, administrative databases) Extensible web-based application What is OT? Surgery? All entities can participate on a limited basis. Hospitals and outpatient dialysis.

Priority Areas for NHSN Development Inclusion of process measures linked to outcomes Surgical prophylaxis Central line insertion practices Completion of HCP Safety Component NaSH  NHSN Influenza pilot: vaccine coverage and use of antiviral medications

How do we develop policy?

Healthcare Infection Control Practices Advisory Committee (HICPAC)

Healthcare Infection Control Practices Advisory Committee MISSION Advise the US Secretary of Health and the Director of CDC regarding the practice of infection control and strategies for surveillance, prevention and control of antimicrobial resistance, and related adverse events in healthcare settings

CDC/HICPAC GUIDELINE SCOPE TARGET AUDIENCE: • clinicians • infection control professionals • public health officials • regulators TARGET SETTINGS: • Inpatient • Outpatient • Home care • Long term care

Ranking Scheme for HICPAC Recommendations (2001) CATEGORY IA. Strongly recommended for all hospitals and strongly supported by well-designed experimental or epidemiologic studies. CATEGORY IB. Strongly recommended for all hospitals and viewed as effective by experts in the field and a consensus of HICPAC based on strong rationale and suggestive evidence, even though definitive scientific studies may not have been done. CATEGORY IC. Required for implementation, as mandated by federal or state regulation or standard. CATEGORY II. Suggested for implementation in many hospitals. Recommendations may be supported by suggestive clinical or epidemiologic studies, a strong theoretical rationale, or definitive studies applicable to some but not all hospitals. NO RECOMMENDATION; UNRESOLVED ISSUE. Practices for which insufficient evidence or consensus regarding efficacy exists.

CDC/HICPAC Guideline RATING SYSTEM CATEGORY EVIDENCE PRACTICE IA/IB STRONG RECOMMENDED IC LACKING REQUIRED BY REGULATION II GOOD SUGGESTED NO REC INSUFFICIENT UNRESOLVED CONTRADICTORY

Challenges/Issues Subject matter experts vs. methodologic experts Resources for systematic reviews Limited randomized trials User needs vs available science (e.g., expansion to non-hospital settings)

PART II: Provides summary of practice recommendations Healthcare Infection Control Practices Advisory Committee GUIDELINE FORMAT PART I: Provides review and synthesis of available research on guideline topic and established scientific rationale for recommendations PART II: Provides summary of practice recommendations PART III: Provides performance indicators for institutions to monitor success in implementing recommended practices

Summary Prevention of SSI require a multifaceted approach targeting pre-, intra-, and postoperative factors Current surveillance systems do collect data on perioperative processes Increasing shift of surgical procedures to outpatient settings and decrease in postoperative length of stay complicate surveillance efforts Incidence is generally low; so studies would require large sample size Some prevention practices (e.g. hand hygiene) would be difficult to study using traditional randomized controlled trial research design

PREVENTION IS PRIMARY! Protect patients…protect healthcare personnel… promote quality healthcare! Division of Healthcare Quality Promotion

Division of Healthcare Quality Promotion (DHQP) website To obtain HICPAC guidelines visit the Division of Healthcare Quality Promotion (DHQP) website http://www.cdc.gov/ncidod/hip/default.htm