Surgical Site Infection Risk Index Research Articles

Epidemiological surveillance of surgical site infections in large joint replacement

Joint replacement is a reliable and effective surgery that allows profound pain relief and restores joint function in patients. Despite the progress made and the experience gained in joint replacement, surgical site infection is one of the leading postoperative complications. It can proceed as a periprosthetic joint infection, osteomyelitis, sepsis and lead to disabled or dead outcomes. Systematization of risk factors for infectious complications plays an important role as an element of epidemiological surveillance system optimization. Age, the presence of concomitant diseases (for example, diabetes mellitus, cancer, arthritis and systemic collagenosis), carriage of antimicrobial-resistant microorganisms, infectious and inflammation both outside and in the area of surgery, and external factors (surgery duration, correct antibiotic prophylaxis and surgeon's experience) are the most significant risk factors for periprosthetic joint infection. In world practice, the National Nosocomial Infections Surveillance System surgical site infection risk index is used. This criterion does not consider all potential risk factors. It is important to analyze and rank the identified risk factors according to the impact on the development of infectious complications in organizing an epidemiological surveillance system process in a medical organization. Risk factors analysis will identify the most significant modifiable factors for the development, implementation and execution of organizational, preventive measures and epidemic control. The creation and implementation of a standardized preoperative protocol based on a risk factors assessment will allow predicting the surgery outcome and arguing the strategy and tactic of preventive measures.

Surgical site infection in a Greek general surgery department: who is at most risk?

Surgical site infections (SSIs) are associated with protracted hospitalisation, antibiotics administration, and increased morbidity and mortality. This work investigated the incidence rate of SSIs in the Department of General Surgery at the University Hospital of Ioannina, Greece, the associated risk factors and pathogens responsible. In this prospective cohort study, patients who underwent elective procedures under general anaesthesia were enrolled. Risk factors monitored included age, sex, body mass index, smoking, alcohol consumption, preoperative length of stay, chemoprophylaxis, intensive care unit (ICU) stay, American Society of Anesthesiology (ASA) score, and the National Nosocomial Infections Surveillance System (NNIS) basic SSI risk index. Of the 1058 enrolled patients, 80 (7.6%) developed SSIs. Of the total cohort, 62.5% of patients received chemoprophylaxis for >24 hours. A total of 20 different pathogens, each with multiple strains (n=108 in total), were identified, 53 (49.5%) Gram-negative rods, 46 (42%) Gram-positive cocci, and nine (8.4%) fungi (Candida spp.). Escherichia coli was the prevalent microorganism (24.3%). SSI-related risk factors, as defined by univariate analysis, included: ICU stay, ASA score >2 (p<0.001), NNIS score >0, and wound classes II, III, and IV. Also, serum albumin levels <3.5g/dl were associated with increased rate of SSIs. The multivariate model identified an NNIS score of >0 and wound classes II, III, and IV as independent SSI-related risk factors. This study showed high SSI rates. Several factors were associated with increased SSI rates, as well as overuse of prophylactic antibiotics. The results of the present study could be a starting point for the introduction of a system for recording and actively monitoring SSIs in Greek hospitals, and implementation of specific guidelines according to risk factors.

Does surgical site infection after Caesarean section in Polish hospitals reflect high-quality patient care or poor postdischarge surveillance? Results from a 3-year multicenter study

Caesarean sections (CSs) are associated with a high infection risk. Surgical site infection (SSI) incidence is among the markers of effectiveness of infection prevention efforts. The aim of this study was to analyze risk factors for SSI, incidence, and microbiology in patients who underwent CS. The study was conducted during 2013-2015 using active infection surveillance in 5 Polish hospitals according to the European Centre for Disease Prevention and Control surveillance network known as HAI-Net. For each procedure, the following data were registered: age, American Society of Anesthesiologists score, procedure time, elective or emergency procedure, use of perioperative antibiotic prophylaxis, microbiology, the treatment used, and other information. SSI incidence was 0.5% and significant differences were noted among hospitals (between 0.1% and 1.8%), for different American Society of Anesthesiologists scales (between 0.2% and 4.8%) and different values of standardized SSI risk index (between 0.0% and 0.8%). In 3.1% of procedures, with no antibiotic prophylaxis, SSI risk was significantly higher. Deep infections dominated: 61.5% with superficial infections in only approximately 30% of cases and 2.6% of infections were detected postdischarge without readmissions. Results showed high incidence of SSI in Poland without perioperative antibiotic prophylaxis, and secondly, ineffective surveillance according to CS status, considering outpatient obstetric care. Without postdischarge surveillance, it is not possible to recognize the epidemiologic situation, and further, to set priorities and needs when it comes to infection prophylaxis, especially because such low incidence may indicate no need for improvement in infection control.

Risk of surgical site infections following hip and knee arthroplasty: results of the ISChIA-GISIO study.

Surgical Site Infection (SSI) is one of the major complications following insertion of hip or knee prosthesis. The aim of the present study was to describe rates of SSIs and associated risk factors during hip and knee prosthesis procedures in Italian hospitals. Italian hospitals were invited to join the ISChIA (Surgical Site Infections in Arthroplasty Surgery) project and participated in the study on a voluntary basis. SSI surveillance was performed according to the Hospitals in Europe Link for Infection Control through Surveillance (HELICS) -SSI protocol. The study population consisted of all patients who had a prosthetic knee or hip joint replacement between March 2010 and February 2011. Only elective operations were include. A total of 14 hospitals and 1285 surgical procedures were included. SSI cumulative incidence was 1.3 per 100 hip and 2.4 per 100 knee surgical procedures; a significant positive trend of SSI incidences was observed with increasing SSI risk index. In multivariate analysis, considering hip procedures, the single independent risk factor associated to SSI was operation length (RR: 4.54; 95%CI: 1.06-19.48). For knee procedures, no significant risk factor was identified. In the present study, SSI cumulative incidence was in the range of European data. However, a larger number of operations is needed to better estimate SSI rates. A second edition of the ISChIA project has been already conducted and results of the two surveys will provide new insight to further our knowledge for infection control.

Applicability of the surgical site infection risk index to patients undergoing cardiac, neurologic and orthopedic surgery

Introduction: The surgical site infection risk index (SSIRI) includes three risk factors for surgical site infection (SSI): potential for surgical contamination, duration of surgery, and patient’s ASA score. A patient having a preoperative American Society of Anesthesiologists (ASA) score of III, IV or IV; a surgery classified as either contaminated or dirty-infected; an operation with duration of surgery more than T hours, where T depends on the surgical procedure being performed are considered in risk of SSI. The SSIRI can be used as a method of postoperative surveillance. The aim of this study is to analyze the applicability of the SSIRI to patients undergoing cardiac, neurologic and orthopedic surgery. Methods: A retrospective cohort study including patients undergoing cardiac, neurological and orthopedic surgeries considered major, from January to December 2014, evaluated through review of medical charts of patients admitted to a university hospital in southern Brazil. Values of p <0.05 were considered significant. Results: A total of 761 patients were included in the study; of these, 122 (16%) developed SSI. The SSIRI did not demonstrate statistical significance to distinguish the patients most likely to develop SSI between the four levels of the ASA score. Black and brown patients, patients who underwent intraoperative blood transfusion, and patients who underwent surgical reintervention were more susceptible to SSI. Conclusions: The SSIRI could not be used as a method of postoperative surveillance for patients in the present study. The other risk factors found may serve as a guide to articulate SSI prevention strategies and, thus, minimize chances of development of serious infections. Keywords: Postoperative complications; infection; risk index

Model Assessment and Development of Risk Stratification of Surgical Site Infection Following Cesarean Delivery for a High-Risk, Urban Population

Background: Surgical site infection (SSI) remains a major cause of morbidity despite efforts aimed at prevention and treatment. Risk stratification tools identify patients at greatest risk of SSI. Two models of stratification are: 1) the Centers for Disease Control and Prevention’s National Healthcare Safety Network SSI Risk Index (NHSN), which assigns risk based on surgery duration, surgical wound contamination and physical status; and 2) the New Risk Stratification Schema (NRSS). The NRSS aimed to improve upon NHSN by incorporating five variables: diabetes control, body mass index (BMI), chorioamnionitis, methods of placental extraction and skin closure.

Fatores relacionados à adesão às recomendações para administração de redose em cirurgias limpas

Surgical site infections (SSIs) are one of the main adverse events among surgical patients, being responsible for 20% of healthcare-associated infections (HAIs). Surgical antibiotic prophylaxis is one of the practices used to prevent SSIs, however, compliance with recommendations is low. A retrospective observational cross-sectional study investigated the index of compliance with redose and its relationship to characteristics of the procedures and individuals. A total of 748 records of cardiac, orthopedic and neurological surgeries were assessed. Of these, 90 had an indication of redose, which was administered in 26.6% of the surgeries. Compliance was significantly higher in cardiac surgeries (34.3%) and those of greater SSI risk index. In conclusion, compliance with recommendations for redose administration is low and improving the process of surgical antibiotic prophylaxis use is needed. The use of technologies in association with awareness, motivation of the teams and involvement of the nursing staff may constitute alternatives.

Proposal for a sub‐classification of hepato‐biliary‐pancreatic operations for surgical site infection surveillance following assessment of results of prospective multicenter data

Surgical site infection (SSI) surveillance in Japan is based on the National Nosocomial Infection Surveillance system, which categorizes all hepato-biliary-pancreatic surgeries, except for cholecystectomy, into "BILI." We evaluated differences among BILI procedures to determine the optimal subdivision for SSI surveillance. We conducted multicenter SSI surveillance at 20 hospitals. BILI was subdivided into choledochectomy, pancreatoduodenectomy, hepatectomy, hepatectomy with biliary reconstruction, pancreatoduodenectomy with hepatectomy, distal pancreatectomy and total pancreatectomy to determine the optimal subdivision. The outcome of interest was SSI. Univariate and multivariate analyses were performed to determine the predictive significance of variables in each type of surgery. 1,926 BILI cases were included in this study. SSI rates were 23.2 % for all BILI; for choledochectomy 23.6 %, pancreatoduodenectomy 39.3 %, hepatectomy 12.8 %, hepatectomy with biliary reconstruction 41.9 %, pancreatoduodenectomy with hepatectomy 27.3 %, distal pancreatectomy 31.8 %, and total pancreatectomy 20.0 %. SSI rates for hepatectomy were significantly lower than those for non-hepatectomy BILI. Risk factors for developing SSI with hepatectomy were drain placement and long operative duration, while for non-hepatectomy BILI, risk factors were use of intra-abdominal silk sutures, SSI risk index and long operative duration. Hepatectomy and non-hepatectomy BILI differ with regard to the incidence of and risk factors for developing SSI. These surgeries should be assessed separately when conducting SSI surveillance.

Risk factors and outcomes associated with surgical site infections after craniotomy or craniectomy

Many studies that have evaluated surgical site infections (SSIs) after craniotomy or craniectomy (CRANI) did not use robust methods to assess risk factors for SSIs or outcomes associated with SSIs. The authors conducted the current study to identify risk factors for SSIs after CRANI procedures and to evaluate outcomes attributed to SSIs. The authors performed a nested case-control study of patients undergoing CRANI procedures between 2006 and 2010 at the University of Iowa Hospitals and Clinics. They identified 104 patients with SSIs and selected 312 controls. They collected data from medical records and used multivariate analyses to identify risk factors and outcomes associated with SSIs. Thirty-two percent of SSIs were caused by Staphylococcus aureus, 88% were deep incisional or organ space infections, and 70% were identified after discharge. Preoperative length of stay (LOS) ≥ 1 day was the only significant patient-related factor in the preoperative model (OR 2.1 [95% CI 1.2-3.4]) and in the overall model (OR 1.9 [95% CI 1.1-3.3]). Procedure-related risk factors that were significant in the overall model included Gliadel wafer use (OR 6.7 [95% CI 2.5-18.2]) and postoperative CSF leak (OR 3.5 [95% CI 1.4-8.5]). The preoperative SSI risk index, including body mass index, previous brain operation, chemotherapy on admission, preoperative LOS, procedure reason, and preoperative glucose level, had better predictive efficacy (c-statistic = 0.664) than the National Healthcare Safety Network risk index (c-statistic = 0.547; p = 0.004). Surgical site infections were associated with increased LOS during the initial hospitalizations (average increase of 50%) or readmissions (average increase of 100%) and with an increased risk of readmissions (OR 7.7 [95% CI 4.0-14.9]), reoperations (OR 36 [95% CI 14.9-87]), and death (OR 3.4 [95% CI 1.5-7.4]). Surgeons were able to prospectively assess a patient's risk of SSI based on preoperative risk factors and they could modify some processes of care to lower the risk of SSI. Surgical site infections substantially worsened patients' outcomes. Preventing SSIs after CRANI could improve patient outcomes and decrease health care utilization.

Factors Associated with Post-Operative Conversion to Methicillin-ResistantStaphylococcus AureusPositivity or Infection in Initially MRSA-Negative Patients

Hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) is associated with morbid, invasive infections and has been implicated in nearly every type of nosocomial infection. Our aim was to identify the risk factors for patient conversion from MRSA negativity pre-operatively to MRSA positivity post-operatively. We retrospectively reviewed all patients at the Veterans Affairs-Boston Health Care System who underwent clean or clean-contaminated surgical procedures during the years 2008 and 2009 and had documented pre-operative nasal polymerase chain reaction (PCR) testing for MRSA. We abstracted post-operative MRSA microbiologic testing results, MRSA infections, surgical site infections (SSIs), surgical prophylaxis data, and SSI risk index, as calculated using the Veterans Affairs Surgical Quality Improvement Project (VASQIP) database variables. All patients who had a negative nasal MRSA PCR result in the 31-day pre-operative period and did not have any positive MRSA clinical swab or culture in the 1-year pre-operative period were defined as MRSA-negative. These patients were classified as converters to MRSA positivity if they had at least one documented positive nasal MRSA PCR swab, culture, nosocomial infection, or SSI within 31 days post-operatively. Among 4,238 eligible patients, 3,890 (92%) qualified as MRSA-negative pre-operatively. A total of 1,432 (37%) of these patients were assessed in the VASQIP database, of whom 34 (2%) converted to MRSA positivity post-operatively. On multivariable logistic regression analysis of the VASQIP sample, age (odds ratio [OR] 1.049; 95% confidence interval [CI] 1.016, 1.083), SSI risk index (OR 2.863; 95% CI 1.251-6.554), and vancomycin prophylaxis alone or in combination (OR 3.223; 95% CI 1.174-8.845) were significantly associated with conversion to MRSA positivity. In pre-operatively MRSA-negative patients, age, SSI risk index, and vancomycin prophylaxis were significant factors for conversion to MRSA positivity post-operatively. Alternatives to vancomycin prophylaxis in non-colonized patients and optimization of patients' SSI risk factors should be considered before elective surgery.

Preoperative Nasal Methicillin-Resistant Staphylococcus aureus Status, Surgical Prophylaxis, and Risk-Adjusted Postoperative Outcomes in Veterans

To determine whether preoperative nasal methicillin-resistant Staphylococcus aureus (MRSA) carriage is a significant predictor of postoperative infections, after accounting for surgical infection risk and surgical prophylaxis. Retrospective cohort study. Veterans Affairs (VA) Boston patients who had nasal MRSA polymerase chain reaction screening performed in the 31 days before clean or clean contaminated surgery in 2008-2009. Postoperative MRSA clinical cultures and infections, total surgical site infections (SSIs), and surgical prophylaxis data were abstracted from administrative databases. MRSA infections were confirmed via chart review. Multivariate analysis of risk factors for each outcome was conducted using Poisson regression. SSI risk index was calculated for a subset of 1,551 patients assessed by the VA National Surgical Quality Improvement Program. Among 4,238 eligible patients, 279 (6.6%) were positive for preoperative nasal MRSA. Postoperative MRSA clinical cultures and infections, including MRSA SSIs, were each significantly increased in patients with preoperative nasal MRSA. After adjustment for surgery type, vancomycin prophylaxis, chlorhexidine/alcohol surgical skin preparation, and SSI risk index, preoperative nasal MRSA remained significantly associated with postoperative MRSA cultures (relative risk [RR], 8.81; 95% confidence interval [CI], 3.01-25.82) and infections (RR, 8.46; 95% CI, 1.70-42.04). Vancomycin prophylaxis was associated with an increased risk of total SSI in those negative for nasal MRSA (RR, 4.34; 95% CI, 2.19-8.57) but not in patients positive for nasal MRSA. In our population, preoperative nasal MRSA colonization was independently associated with MRSA clinical cultures and infections in the postoperative period. Vancomycin prophylaxis increased the risk of total SSI in nasal MRSA-negative patients.

Surgical site infections in adults patients undergoing of clean and contaminated surgeries at a university Brazilian hospital

Surgical site infections are a risk inherent to surgical procedures, especially after digestive surgeries. They occur up to 30 days after surgery, or up to a year later if a prosthesis is implanted. The Surgical-site Infection Risk Index (SIRI), NISS (National Nosocomial Infection Surveillance) methodology, is a method to evaluate the risk of surgical site infections, which takes into account the potential contamination of the surgery, the patient's health status and surgery duration. To evaluate the correlation between the surgical-site infection risk index score on the 1st day postoperatively, and the development of surgical site infection up to 30 days postoperatively. The postoperative surgical site infections (NNIS) was evaluated by following-up in hospital and as an outpatient. The patients followed prospectively were those submitted to elective surgeries, clean (hernioplasties) or contaminated (colorretal), performed by conventional approach at a university hospital, during the period from June 2007 to August 2008. The mean age of the patients was 55.5 years, 133 (65.5%) male; 120 (59.1%) submitted to clean surgeries and 83 (40.9%) contaminated. The global index of surgical site infections was 10.3%; 10 (8.3%) in clean procedures and 111(3.2%) in contaminated ones. Four (19.1%) of the surgical site infections were diagnosed at the time of hospitalization and 17 (80.9%) at post-discharge follow-up. Twelve (57.1%) of the surgical site infections were superficial, 2 (9.5%) deep and 7 (33.3%) at a specific site. Of these, 5 (6.6%) were in patients classified as SIRI 0 (76); 9 (15%) for SIRI 1 (60); 5 (9.1%) for SIRI 2 (55) and 2 (16.7%) for SIRI 3. The global index of surgical site infections and its incidence among contaminated procedures are within the expected limits. On the other hand according to SIRI, the surgical site infection indexes are above the expected standards both for the clean and for the contaminated procedures.

The national nosocomial surveillance network in Hungary: results of two years of surgical site infection surveillance

In 2004, a secure web-based national nosocomial infection surveillance system was established in Hungary. The system, named NNSR (Nemzeti Nosocomiális Surveillance Rendszer), is based on the US National Nosocomial Infection Surveillance System (NNIS). Surgical procedures, definitions, surveillance methodology and patient risk indices are those established by NNIS. In this paper, we present the results of the first two years of the surgical patient component of our system. During this period, 41 hospitals participated and selected 11 surgical procedures for surveillance. Altogether 15812 procedures were surveyed and 360 resulting surgical site infections (SSI) were recorded. The overall SSI rate was 2.27%. The most commonly selected procedures and corresponding SSI rates were caesarean section (1.31%), herniorrhaphy (2.09%), cholecystectomy (1.52%) and hip replacement (2.91%). Standardised infection ratios (SIR) were calculated for chosen surgical procedures in order to compare against NNIS published rates. SSI rates for colonic surgery, caesarean section and mastectomy were lower than expected according to the NNIS data but higher for cholecystectomy, herniorrhaphy and hip prosthesis infection rates. We intend to recruit more participating hospitals, leading to a robust national database that can be used to target infection control interventions for patients in Hungary.

Surgical Site Infection in General and Thoracic Surgery: Surveillance of 2 663 Cases in a Japanese Teaching Hospital

We conducted a prospective survey of 2 663 surgical patients in a Japanese teaching hospital to look for any risk factors predisposing to surgical site infection (SSI) other than the National Nosocomial Infection Surveillance (NNIS) System risk indices; namely, performance status, operative time, wound classification, and endoscopic use. Our Infection Control Team recorded data for 5 years using the Japanese SSI surveillance system. We divided the incidence of SSI for each risk index category by the NNIS reference data to produce the standardized infection ratio (SIR). The representative procedure, SSI rate, and SIR in the 2663 patients were as follows: colectomy, 6.0%, 0.917; esophagectomy, 19.4%, 6.020; mastectomy, 0.5%, 0.401; rectal surgery, 8.7%, 1.136; thoracic surgery, 1.5%, 1.137; and biliary surgery, 13.4%, 1.937. We also found age to be a significant risk factor. The NNIS system risk indices should separate rectal surgery from colorectal surgery, and separate esophagectomy from other gastrointestinal surgery. Age should also be included as an SSI risk index.

Implementation and establishment of nationwide surgical site infections surveillance in Japan

ISSUE: There used to be no database against which hospitals can compare their surveillance data for surgical site infections (SSIs). In 1998, the Japanese Nosocomial Infections Surveillance (JNIS) system was established by adopting the U.S. National Nosocomial Infection Surveillance System (NNIS). Its aim was to create the database of SSIs in Japan through surveillance. PROJECT: Hospitals that were willing to submit data were invited to participate in this project. Data collection began in 1999. Data were submitted via e-mail, using Excel™ spreadsheets. Feedback was given about once a year by paper reports to each hospital. RESULTS: The number of participating hospitals increased from eight in 1999 to about 80 by the end of 2004. A total 20,948 cases were surveyed from November 1998 through December 2003. The primary operative procedure was abdominal surgery because the persons responsible for surveillance are mainly gastrointestinal surgeons. Unlike in the United States, in Japan there are insufficient numbers of certified infection control practitioners, and surgeons are interested in performing surveillance on their own. Risk stratification is a necessary factor comparing hospital data against data in the JNIS system. We used the NISS SSI risk index system and it suited our data. On other hand, we modified system by dividing large bowel operation (COLO) into two different categories (COLN for colon, and REC for rectum) because many Japanese surgeons think that the risk of SSIs is lower for colon surgery than for rectal surgery due to differences in anatomy and the complexity of the operations. The overall SSI rates in COLN and REC procedures were 14.8% and 17.3%, respectively. Even though the difference was not statistically significant (p=0.12, chi square test), it seemed to support the surgeons' perceptions. Also, the SSI rate for esophageal operations, which we separated, was 21.6% (19/43) and much higher than that of OGIT category (5.2%), where it is included in the NNIS system. Feedback data included SSI rates by procedure and by other factors such as age, gender, and SSI rate-stratified NISS risk index. Questionnaires sent out in 2003 showed overall satisfaction among participating hospitals. LESSONS LEARNED: A nationwide SSI surveillance system was implemented in Japan, and we were able to create a national reference data in the past 5 years.

A New Surgical-Site Infection Risk Index Using Risk Factors Identified by Multivariate Analysis for Patients Undergoing Coronary Artery Bypass Graft Surgery

To develop a new, simple, and practical risk index for patients undergoing coronary artery bypass graft (CABG) surgery, to develop a preoperative risk index that is predictive of surgical-site infection (SSI), and to compare the new risk indices with the National Nosocomial Infections Surveillance (NNIS) System risk index. Potential risk factor and infection data were collected prospectively and analyzed by multivariate analysis. Two new risk indices were constructed and then compared with the NNIS System risk index for predictive power for SSI. Alfred Hospital is a 350-bed, university-affiliated, tertiary-care referral center. The cardiothoracic unit performs approximately 650 CABG procedures per year. All patients undergoing CABG surgery within the cardiothoracic unit at Alfred Hospital between December 1, 1996, and September 29, 2000, were included. Potential risk factor data were complete for 2,345 patients. There were 199 SSIs. Obesity (odds ratio [OR], 1.78; 95% confidence interval [CI95], 1.24 to 2.55), peripheral or cerebrovascular disease (OR, 1.64; CI95, 1.16 to 2.33), insulin-dependent diabetes mellitus (OR, 2.29; CI95, 1.15 to 4.54), and a procedure lasting longer than 5 hours (OR, 1.75; CI95, 1.18 to 2.58) were identified as independent risk factors for SSI. With the use of a different combination of these risk factors, two risk indices were constructed and compared using the Goodman-Kruskal nonparametric correlation coefficient (G). kisk index B had the highest G value (0.3405; CI95, 0.2245 to 0.4565), compared with the NNIS System risk index G value (0.3142; CI95, 0.1462 to 0.4822). The G value for risk index A, constructed from preoperative variables only, was 0.3299 (CI9,, 0.2039 to 0.4559). Two new risk indices have been developed. Both indices are as predictive as the NNIS System risk index. One of the new risk indices can also be applied preoperatively.

Surgical site infection (SSI) rates in the United States, 1992-1998: the National Nosocomial Infections Surveillance System basic SSI risk index.

By use of the National Nosocomial Infections Surveillance (NNIS) System's surgical patient surveillance component protocol, the NNIS basic risk index was examined to predict the risk of a surgical site infection (SSI). The NNIS basic SSI risk index is composed of the following criteria: American Society of Anesthesiologists score of 3, 4, or 5; wound class; and duration of surgery. The effect when a laparoscope was used was also determined. Overall, for 34 of the 44 NNIS procedure categories, SSI rates increased significantly (P< .05) with the number of risk factors present. With regard to cholecystectomy and colon surgery, the SSI rate was significantly lower when the procedure was done laparoscopically within each risk index category. With regard to appendectomy and gastric surgery, use of a laparoscope affected SSI rates only when no other risk factors were present. The NNIS basic SSI index is useful for risk adjustment for a wide variety of procedures. For 4 operations, the use of a laparoscope lowered SSI risk, requiring modification of the NNIS basic SSI risk index.

Surveillance of Surgical-Site Infections: The World Coming Together?

Surgical-site infections (SSIs) are associated with substantial risk of morbidity, resulting in prolongation of hospital stay and monetary costs attributable to the infection.1-3 Reporting surgeon-specific SSI rates back to the surgeon has been shown in a number of studies to reduce SSI rates significantly, with appropriate cautions.4-7 Because of this, several countries have recently examined and reported their SSI experience.8-13 This issue of the Journal brings another article for consideration.14 This article describes the first year of the Dutch national surveillance of SSIs and risk factors. The results, while preliminary, show many of the same findings seen in other studies: ● There are multiple risk factors for SSIs. The Dutch study found age, preoperative length of stay, wound class, anesthesia score, and duration of surgery to be independently important risk factors for SSIs when all procedures were pooled together for analysis. ● Risk factors vary by procedure. The nature and relative importance of the risk factors differed when individual procedures were examined in the Dutch PREZIES (Preventie van Ziekenhuisinfecties door Surveillance [Prevention of Nosocomial Infections Through Surveillance]) Project. ● SSIs are very costly to the healthcare system. The Dutch study found an attributable increased length of stay of 8.2 days for patients with SSIs. In any nation, an additional week or so of hospitalization is expensive. It should not be surprising that so many countries are attempting to monitor this infection. However, the efforts of Geubbels and colleagues point out the difficulties with which all countries struggle in doing so. These include monitoring a national representation based upon a probability sampling of procedures; cooperation of hospitals and, in particular, surgeons; adequate sample size for certain surgical procedures; accuracy of data, especially with regard to postdischarge surveillance; and, ultimately, validity of comparisons with other SSI rates. Despite the difficulties, the Dutch study specifically points out the feasibility of such a surveillance system. The study also confirmed that many of the risk factors from the Basic SSI Risk Index used in the Centers for Disease Control and Prevention (CDC)’s National Nosocomial Infections Surveillance (NNIS) System were risk factors in The Netherlands. Further, there was close correlation of the 75th percentile of duration of surgery between the Dutch system and the NNIS system for similar group procedures. In general, if differences existed, they were minor, with the NNIS durations tending to be longer (Table). The differences may be due simply to smaller sample size and thus poorer estimates for the 75th percentiles in the PREZIES Network compared to the NNIS System; the distributions of the specific ICD-9 codes may have been different for the procedures (which are grouped codes in both systems); the actual measure of duration of surgery may have differed slightly between The Netherlands and the United States; or Dutch surgeons may have been slightly faster at operating. The reasons for the differences in duration of surgery are not any clearer than the reasons for differences in the SSI rates. Thus, even for the simplest of variables, duration of surgery, comparisons across surveillance systems are difficult; only where enormous differences occur can conclusions be drawn. For example, a comparison of surveillance systems for SSIs in Belgium and The Netherlands found an extraordinary difference in the use of antimicrobial prophylaxis for herniorrhaphies (3.7% in The Netherlands vs 41.9% in Belgium).15 This observation led directly to closer examination of antimicrobial prophylaxis in Belgium.16 More recently, at the 4th Decennial International Conference on Nosocomial and Healthcare-Associated

Surgical-site infection rates in patients who undergo elective surgery on the same day as their hospital admission.

To follow over time surgical-site infection (SSI) rates in patients admitted to the hospital on the same day as their elective surgery (group I), and to compare these rates with those of other surgical patients who also required postoperative hospitalization but either were hospitalized for 1 or more days immediately prior to surgery or underwent surgery on a nonelective basis (group II). Observation of overall SSI rates over time for group I and II patients and study of risk factors associated with increased SSI rate among group I neurosurgical patients. A 900-bed, tertiary-care community hospital with >10,000 surgical procedures performed each year on patients requiring postoperative hospital stay. A total of 48,464 surgical procedures were performed on consecutive patients from 1990 to 1994, with 18,794 (39%) involving group I patients. In addition, 511 consecutive procedures performed on neurosurgical patients requiring postoperative hospitalization from July 1994 to May 1995 were analyzed. In 1990, the overall SSI rate of group I patients was significantly lower than that of group II patients (0.4% vs 1.3%, relative risk [RR], 3.6; 95% confidence interval [CI95], 2-6.4; P<.0001), but, by 1994, there was no longer any significant difference between the SSI rates of group I and II patients (1.8% and 1.6%, respectively; P=.38). In 1994, the SSI rate in group I neurosurgical patients was significantly greater than that of group II patients (3.4% vs 0.4%; RR, 8.3; CI95, 1.05-66; P=.02). During the period April through September 1994 (warm months), group I neurosurgical patients were associated with a significantly lower American Society of Anesthesiologists score and SSI risk index (based on National Nosocomial Infection Surveillance System data) and a higher likelihood of having "clean-class" wounds, but significantly greater-than-expected SSI rate when adjusted for patient risk index and type of procedure (4.7% vs 1.4%; RR, 3.3; CI95, 1.3-8.6; P=.02). During the same period, the observed and expected SSI rates were not significantly different for group II neurosurgical patients. As a whole, the SSI rates among patients undergoing elective surgery on the same day of their hospital admission is no longer significantly lower than that of other patients who also require postoperative hospitalization. For certain procedures, such as those commonly performed on the neurosurgical service, elimination of preoperative hospital stay may be associated with greater-than-expected risk of SSI.

Comparing surgical site infection (SSI) rates using the NNIS SSI risk index and the standardized infection ratio

Comparing surgical site infection (SSI) rates using the NNIS SSI risk index and the standardized infection ratio