Indices of surgical site infection risk and prediction of other adverse outcomes during hospitalization.

OBJECTIVE: To assess which adverse postsurgical outcomes are best predicted by the Study on the Efficacy of Nosocomial Infection Control (SENIC) index and the National Nosocomial Infection Surveillance system (NNIS) index. DESIGN: Prospective cohort study. SETTING: The service of general surgery at a tertiary care hospital. PATIENTS: A consecutive series of patients hospitalized for more than 1 day (n=2,989). RESULTS: The outcome best predicted by the SENIC and NNIS indices was assessed by estimating the area under the receiver operating characteristic (ROC) curve. The areas under the ROC curves for nosocomial infection and in-hospital death were higher for the NNIS index than they were for the SENIC index (P<.05). The NNIS index predicted in-hospital death better than it predicted surgical site infection (area under the ROC curve+/-SE, 0.836+/-0.022 vs 0.689+/-0.017; P=.001). CONCLUSIONS: The NNIS index is superior to the SENIC index for all adverse postsurgical outcomes. Its ability to predict in-hospital mortality is clearly better than its ability to predict surgical site infection.     

Applicability of two surgical-site infection risk indices to risk of sepsis in surgical patients.

OBJECTIVE: To compare the ability of the Study of the Efficacy of Nosocomial Infection Control (SENIC) and the National Nosocomial Infection Surveillance (NNIS) indices to predict the development of nosocomial sepsis in subjects undergoing surgery. DESIGN: 1-year prospective case-control study. SETTING: A tertiary-care center in Spain. PATIENTS: Cases were surgical patients with nosocomial sepsis defined using the criteria of the Consensus Conference on Sepsis, identified by daily prospective surveillance. METHODS: Controls were randomly selected from the daily list of surgical inpatients. Data were prospectively collected. To determine whether either index added explanatory information to the other, two methods were used. The first method involved computing a set of residuals for both variables. Residuals and primary variables were introduced in logistic regression models. The second method evaluated both indices with the Goodman-Kruskal (G) nonparametric coefficient. RESULTS: 99 cases and 97 controls were included. After controlling for confounders, both the SENIC index (P<.001) and the NNIS index (P=.04) showed a significant trend. Residuals of the SENIC index added discriminating ability to the NNIS index, whereas residuals of the NNIS index did not improve the prediction ability of the SENIC index. Similar results were yielded by the G statistic: the SENIC index showed higher predictive power than the NNIS index (G=0.56 vs G=0.41). CONCLUSIONS: Both indices performed about equally well for discriminating risk of nosocomial sepsis. The SENIC index had a somewhat better ability than the NNIS index only when the number of discharge diagnoses (not truly a predictive factor) were involved in the calculation of the SENIC index.     

An alternative scoring system to predict risk for surgical site infection complicating coronary artery bypass graft surgery.

OBJECTIVE: To analyze the risk factors for surgical site infection (SSI) complicating coronary artery bypass graft (CABG) surgery and to create an alternative SSI risk score based on the results of multivariate analysis. METHODS: A prospective cohort study involving inpatient and laboratory-based surveillance of patients who underwent CABG surgery over a 27-month period from January 1, 2003 through March 31, 2005. Data were obtained from 6 acute care hospitals in Victoria, Australia, that contributed surveillance data for SSI complicating CABG surgery to the Victorian Hospital Acquired Infection Surveillance System Coordinating Centre and the Australasian Society of Cardiac and Thoracic Surgeons, also in Victoria. RESULTS: A total of 4,633 (93%) of the 4,987 patients who underwent CABG surgery during this period were matched in the 2 systems databases. There were 286 SSIs and 62 deep or organ space sternal SSIs (deep or organ space sternal SSI rate, 1.33%). Univariate analysis revealed that diabetes mellitus, body mass index (BMI) greater than 35, and receipt of blood transfusion were risk factors for all types of SSI complicating CABG surgery. Six multivariate analysis models were created to examine either preoperative factors alone or preoperative factors combined with operative factors. All models revealed diabetes and BMI of 30 or greater as risk factors for SSI complicating CABG surgery. A new preoperative scoring system was devised to predict sternal SSI, which assigned 1 point for diabetes, 1 point for BMI of 30 or greater but less than 35, and 2 points for BMI of 35 or greater. Each point in the scoring system represented approximately a doubling of risk of SSI. The new scoring system performed better than the National Nosocomial Infections Surveillance System (NNIS) risk index at predicting SSI. CONCLUSION: A new weighted scoring system based on preoperative risk factors was created to predict sternal SSI risk following CABG surgery. The new scoring system outperformed the NNIS risk index. Future studies are needed to validate this scoring system.     

Evaluation of the SENIC risk index in a Spanish university hospital.

OBJECTIVE: To assess the performance of the Study of the Efficacy of Nosocomial Infection Control (SENIC) risk index for the evaluation of the risk of surgical-site infection (SSI) in a country other than the United States, having a different health system. SETTING: 350-bed university hospital in Spain belonging to the National Health System (Insalud). DESIGN: Observational cohort study of 1,019 patients who underwent consecutive surgery from January to December 1992. Surgical-infection risk factors assessed by the traditional wound-classification system (clean, clean-contaminated, contaminated, and dirty-infected wound) and by the SENIC risk index (length of intervention more than 2 hours, more than three discharge diagnoses, abdominal surgery, and contaminated or dirty-infected wound) were compared by forward logistic regression. RESULTS: The SENIC risk index showed a greater ability to predict SSI than the traditional wound-classification system. The study carried out in our institution reproduced the estimators provided by the SENIC study in the United States. The SENIC risk index provided a stepwise increase in SSI rates, according to the number of factors present, for every traditional wound-classification group. In the case of clean wounds, the incidence of surgical infection (per 100 interventions) increased (1.5, 2.4, 5.3, and 50; P<.001) for patients having from zero to three risk factors of the SENIC risk index. CONCLUSIONS: This study shows that the SENIC risk index results are reproducible, and the index can be used to compare rates of wound infection across countries with different health systems than the United States.     

Risk adjustment for surgical site infection after median sternotomy in children.

OBJECTIVE: To determine whether the National Nosocomial Infections Surveillance (NNIS) System risk index adequately stratified a population of pediatric patients undergoing cardiac surgery according to the risk of developing surgical site infection (SSI). DESIGN: A retrospective, case-control study. SETTING: An urban tertiary care children's hospital. PATIENTS: Patients who had a median sternotomy performed between January 1, 1995, and December 31, 2003, were eligible for inclusion in the study. For all case patients, medical records were reviewed to verify that all patients met the case definition for SSI. Control subjects were chosen randomly from among all patients who underwent median sternotomy during the study period who did not develop SSI. RESULTS: Thirty-eight patients with SSI and 172 patients without SSI were included. One hundred six patients (50%) were male. The median patient age was 4 months. The sensitivity of the NNIS risk index with cutoff scores of 0 to 1 and 2 to 3 was 20%. The distribution of patients with SSI for an NNIS risk index score of 0 was 0%; for a score of 1, 80%; for a score of 2, 20%; and for a score of 3, 0%. The distribution of patients without SSI for a scores of 0 was 4%; for a score of 1, 87%; for a score of 2, 9%; and for a score of 3, 0%. The area under the receiver-operating characteristic curve (AUC) of the original NNIS risk index was 0.57. The modified risk indices did not perform significantly better, with an AUC range of 0.58 to 0.73. CONCLUSIONS: The NNIS risk index did not adequately stratify pediatric patients undergoing median sternotomy according to their risk of developing an SSI. Various modifications to the risk index yielded only slightly higher AUC values.     

Incidence of surgical-site infections and the validity of the National Nosocomial Infections Surveillance System risk index in a general surgical ward in Santa Cruz, Bolivia.

OBJECTIVES: To estimate the frequency of and risk factors for surgical-site infections (SSIs) in Bolivia, and to study the performance of the National Nosocomial Infections Surveillance (NNIS) System risk index in a developing country. DESIGN: A prospective study with patient follow-up until the 30th postoperative day. SETTING: A general surgical ward of a public hospital in Santa Cruz, Bolivia. PATIENTS: Patients admitted to the ward between July 1998 and June 1999 on whom surgical procedures were performed. RESULTS: Follow-up was complete for 91.5% of 376 surgical procedures. The overall SSI rate was 12%. Thirty-four (75.6%) of the 45 SSIs were culture positive. A logistic regression model retained an American Society of Anesthesiologists score of more than 1 (odds ratio [OR], 1.87), a not-clean wound class (OR, 2.28), a procedure duration of more than 1 hour (OR, 1.81), and drain (OR, 1.98) as independent risk factors for SSI. There was no significant association between the NNIS System risk index and SSI rates. However, a "local" risk index constructed with the above cutoff points showed a linear trend with SSI (P < .001) and a relative risk of 3.18 for risk class 3 versus a class of less than 3. CONCLUSIONS: SSIs cause considerable morbidity in Santa Cruz. Appropriate nosocomial infection surveillance and control should be introduced. The NNIS System risk index did not discriminate between patients at low and high risk for SSI in this hospital setting, but a risk score based on local cutoff points performed substantially better.     

Performance of the national nosocomial infections surveillance risk index in predicting surgical site infection in australia.

BACKGROUND: The Victorian Hospital Acquired Infection Surveillance System (VICNISS) hospital-acquired infection surveillance system was established in 2002 in Victoria, Australia, and collates surgical site infection (SSI) surveillance data from public hospitals in Australia. OBJECTIVE: To evaluate the association between the US National Nosocomial Infections Surveillance (NNIS) system's risk index and SSI rates for 7 surgical procedures. METHODS: SSI surveillance was performed with NNIS definitions and methods for surgical procedures performed between November 2002 and September 2004. Correlations were assessed using the Goodman-Kruskal gamma statistic. RESULTS: Data were submitted for the following numbers of procedures: appendectomy, 545; coronary artery bypass graft (CABG), 4,632; cholecystectomy, 1,001; colon surgery, 623; cesarean section, 4,857; hip arthroplasty, 3,825; and knee arthroplasty, 2,416. NNIS risk index and increasing SSI rate were moderately well correlated for appendectomy ( gamma =0.55), colon surgery ( gamma =0.48), and cesarean section ( gamma =0.42). A fairly positive correlation was found for cholecystectomy ( gamma =0.17), hip arthroplasty ( gamma =0.2), and knee arthroplasty ( gamma =0.16). However, for CABG surgery, a poor association was found ( gamma =0.02). CONCLUSIONS: The NNIS risk index was positively correlated with an increasing SSI rate for all 7 procedures; the strongest correlation was found for appendectomy, cesarean section, and colon surgery, and the poorest correlation was found for CABG surgery. We believe that risk stratification with the NNIS risk index is appropriate for comparison of data for most procedures and superior to use of no risk adjustment. However, for some procedures, particularly CABG, further studies of alternative risk indexes are needed to better stratify patients.     

Risk stratification for surgical site infections in Australia: evaluation of the US National Nosocomial Infection Surveillance risk index

This study evaluated the US National Nosocomial Infection Surveillance (NNIS) risk index (RI) in Australia for different surgical site infection (SSI) outcomes (overall, in-hospital, post-discharge, deep-incisional and superficial-incisional infection) and investigated local risk factors for SSI. A SSI surveillance dataset containing 43 611 records for 13 common surgical procedures, conducted in 23 hospitals between February 2001 and June 2005, was used for the analysis. The NNIS RI was evaluated against the observed SSI data using diagnostic test evaluation statistics (sensitivity, specificity, positive predictive value, negative predictive value). Sensitivity was low for all SSI outcomes (ranging from 0.47 to 0.69 and from 0.09 to 0.20 using RI thresholds of 1 and 2 respectively), while specificity varied depending on the RI threshold (0.55 and 0.93 with thresholds of 1 and 2 respectively). Mixed-effects logistic regression models were developed for the five SSI outcomes using a range of available potential risk factors. American Society of Anaesthesiologists (ASA) physical status score >2, duration of surgery, absence of antibiotic prophylaxis and type of surgical procedure were significant risk factors for one or more SSI outcomes, and risk factors varied for different SSI outcomes. The discriminatory ability of the NNIS RI was insufficient for its use as an accurate risk stratification tool for SSI surveillance in Australia and its sensitivity was too low for it to be appropriately used as a prognostic indicator.     

结直肠手术手术部位感染危险因素的logistic回归分析

目的探索结直肠手术手术部位感染(SSI)的危险因素,为制定SSI预防措施提供依据。方法回顾性调查2013年6月—2016年6月某院胃肠外科结直肠手术患者,对影响感染的相关危险因素进行非条件logistic回归分析。结果 397例结直肠手术患者中,67例发生SSI,SSI发生率为16.88%。logistic回归分析结果显示,吸烟、低清蛋白、手术医生年资5年、围手术期抗菌药物使用不规范、NNIS评分高5项因素是结直肠手术SSI的独立危险因素(均P0.05)。结论结直肠手术SSI存在多种危险因素,应重视并针对其危险因素制定干预措施,以降低SSI发生率。     

Does the Centers for Disease Control's NNIS system risk index stratify patients undergoing cardiothoracic operations by their risk of surgical-site infection?

BACKGROUND: In 1991, the Centers for Disease Control and Prevention devised the National Nosocomial Infection Surveillance (NNIS) System risk index to stratify populations of surgical patients by the risk of acquiring surgical-site infections (SSIs). OBJECTIVE: To determine whether the NNIS risk index adequately stratifies a population of cardiothoracic surgery patients by the risk of developing SSI. DESIGN: Case-control study. SETTING: The University of Iowa Hospitals and Clinics, a 900-bed, midwestern, tertiary-care hospital. PATIENTS: 201 patients with SSIs identified by prospective infection control surveillance and 398 controls matched by age, gender, type of procedure, and date of procedure. All patients underwent cardiothoracic operative procedures between November 1990 and January 1994. RESULTS: The SSI rate was 7.8%. Seventy-four percent of cases and 80% of controls had a NNIS risk index score of 1; 24% of cases and 16% of controls had a score of 2 (P=.05). Patients with a NNIS risk score > or =2 were 1.8 times more likely to develop an SSI than those with a NNIS score <2 (odds ratio, 1.83; 95% confidence interval, 1.14-2.94, P=.01). The duration of the procedure was the only component of the index that stratified the population by risk of SSI. CONCLUSIONS: The risk of SSI after cardiothoracic operations increases as the NNIS risk index score increases. However, this index only dichotomized the patient population on the basis of the procedure duration. More research is needed to develop a risk index that adequately stratifies the risk of SSI after cardiothoracic operations.     

A new surgical-site infection risk index using risk factors identified by multivariate analysis for patients undergoing coronary artery bypass graft surgery.

OBJECTIVES: 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. DESIGN: 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. SETTING: Alfred Hospital is a 350-bed, university-affiliated, tertiary-care referral center. The cardiothoracic unit performs approximately 650 CABG procedures per year. PATIENTS: All patients undergoing CABG surgery within the cardiothoracic unit at Alfred Hospital between December 1, 1996, and September 29, 2000, were included. RESULTS: 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). CONCLUSION: 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.     

Surveillance for surgical site infection after hospital discharge: a surgical procedure-specific perspective.

OBJECTIVE: To estimate the rate of surgical site infection (SSI) occurring after hospital discharge, to evaluate whether limiting surveillance to inpatients underestimates the true rate of SSI, and to select surgical procedures that should be included in a postdischarge surveillance program. DESIGN: Prospective surveillance study. SETTING: A surgical ward at a university teaching hospital in Italy. PATIENTS: A total of 264 surgical patients were included in the study. RESULTS: The global SSI rate was 10.6% (28 patients); 17 (60.2%) of patients with an SSI developed the infection after hospital discharge. The overall mean length of postoperative stay (+/-SD) for patients who acquired a postdischarge SSI was 4.9+/-3.7 days, and SSI was diagnosed a mean duration (+/-SD) of 11.5+/-4.5 days after surgery. Among procedures with postdischarge SSIs, those classified by the National Nosocomial Infections Surveillance system (NNIS) as herniorrhaphy, mastectomy, other endocrine system, and other integumentary system were associated with a mean postoperative stay that was less than the mean time between the operation and the onset of SSI. Four (36%) of in-hospital SSIs occurred after procedures with an NNIS risk index of 0, and 7 (64%) occurred after procedures with an NNIS risk index of 1 or higher. Of the 17 SSIs diagnosed after discharge, 14 procedures (82%) had an NNIS risk index of 0, compared with 3 procedures (18%) with an NNIS risk index of 1 or higher. CONCLUSIONS: Our results revealed an increased risk of postdischarge SSI after some types of surgical procedures and suggest that there is an important need to change from generalized to NNIS operative category-directed postdischarge surveillance, at least for procedures locally considered to be high-risk.     

The standardized incidence ratio as a reliable tool for surgical site infection surveillance.

OBJECTIVE: To evaluate whether the standardized incidence ratio (SIR) is a more reliable tool for comparing rates and temporal trends of surgical site infection (SSI) in surgery wards than the incidence rate among patients with an National Nosocomial Infections Surveillance system (NNIS) risk index category of 0. DESIGN: Observational, prospective cohort study in a sequential SSI surveillance system. SETTING: Volunteer surgery wards in a surveillance network in northern France that annually conducted SSI surveillance for 3 months from 1998 to 2000. METHODS: The incidence rate was the number of SSIs divided by the number of patients included, stratified by the NNIS risk index category. SIR was the observed number of SSIs divided by the expected number computed using a multiple regression model. RESULTS: Overall, 26,904 patients in 67 surgery wards were enrolled. Between 1998 and 2000, the SSI incidence rate among patients with NNIS risk index category 0 decreased from 2.1% to 1.4%, which was a 33% reduction (P=.002). The SIR decreased from 1.2 (95% confidence interval [CI], 1.1-1.3) to 0.8 (95% CI, 0.7-0.9), which was a 20% decrease per year and an overall 33% reduction. The number of SSIs was significantly higher than expected in 17 of 201 surveillance periods over the 3 years. The classification of the wards according to the 2 indicators over the 3 years showed that wards with a high SIR did not consistently have the highest SSI incidence rate among patients with NNIS risk index category 0, partly because the type of surgical procedure and the duration of follow-up are not taken into account in the NNIS risk index. CONCLUSION: SIR should be considered a reliable indicator to estimate the reduction in SSI incidence that results from implementation of infection control policies and for comparison of SSI rates between wards.     

Procedure-specific surgical site infection rates and postdischarge surveillance in Scotland.

OBJECTIVE: To investigate the impact of postdischarge surveillance (PDS) on surgical-site infection (SSI) rates for selected surgical procedures in acute care hospitals in Scotland. DESIGN: Prospective surveillance of SSI after selected surgical procedures. SETTING: The Scottish Surveillance of Healthcare Associated Infection Programme (SSHAIP), which is based on the methodology of the Centers for Disease Control and Prevention (CDC) National Nosocomial Infections Surveillance system (NNIS). Thirty-two of 46 acute care hospitals throughout Scotland contributed data to SSHAIP for this study. METHODS: Data were from 21,710 operations that took place between April 1, 2002, and June 30, 2004; nine categories of surgical procedures were analyzed. CDC NNIS system definitions and methods were used for SSI PDS. PDS is a voluntary component of the mandatory SSI surveillance program in Scotland. PDS was categorized as none, passive, active without direct observation, and active with direct observation. RESULTS: From our study information, PDS data were available for 12,885 operations (59%). A total of 2,793 procedures (13%) were associated with passive PDS and 10,092 (46%) with active PDS. The SSI rate among the 8,825 operations with no PDS was 2.61% (95% confidence interval [CI], 2.3%-3.0%), which was significantly lower than the SSI rate found among the 12,885 operations for which PDS was performed (6.34% [95% CI, 5.9%-6.8%]). For breast surgery, cesarean section, hip replacement, and abdominal hysterectomy, the rate of SSI when PDS was performed was significantly higher than that when PDS was not performed (P<.01 for each procedure). No differences in SSI rates were found for surgery to repair fractured neck of the femur or for knee replacement. SSI rates were examined according to procedure type, performance of PDS, and NNIS risk index; rates of SSI increased with NNIS risk index within procedure group and PDS group. Logistic regression analyses confirmed that procedure type, performance of PDS, and NNIS risk index were all statistically independent predictors of report of an SSI (P<.05). CONCLUSIONS: This Scottish national data set incorporates a substantial amount of PDS data. We recommend a procedure-specific approach to PDS, with direct observation of patients after breast surgery, cesarean section, and hysterectomy, for which the length of stay is typically short. Readmission surveillance may be adequate to detect most SSIs after orthopedic surgery or vascular surgery, for which the length of stay is typically longer.     

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.     

Finding a method for optimizing risk adjustment when comparing surgical-site infection rates.

OBJECTIVE: To investigate whether stratification of the risk of developing a surgical-site infection (SSI) is improved when a logistic regression model is used to weight the risk factors for each procedure category individually instead of the modified NNIS System risk index. DESIGN AND SETTING: The German Nosocomial Infection Surveillance System, based on NNIS System methodology, has 273 acute care surgical departments participating voluntarily. Data on 9 procedure categories were included (214,271 operations). METHODS: For each of the procedure categories, the significant risk factors from the available data (NNIS System risk index variables of ASA score, wound class, duration of operation, and endoscope use, as well as gender and age) were identified by multiple logistic regression analyses with stepwise variable selection. The area under the receiver operating characteristic (ROC) curve resulting from these analyses was used to evaluate the predictive power of logistic regression models. RESULTS: For most procedures, at least two of the three variables contributing to the NNIS System risk index were shown to be independent risk factors (appendectomy, knee arthroscopy, cholecystectomy, colon surgery, herniorrhaphy, hip prosthesis, knee prosthesis, and vascular surgery). The predictive power of logistic regression models (including age and gender, when appropriate) was low (between 0.55 and 0.71) and for most procedures only slightly better than that of the NNIS System risk index. CONCLUSION: Without the inclusion of additional procedure-specific variables, logistic regression models do not improve the comparison of SSI rates from various hospitals.     

Suitability of the NNIS index for estimating surgical-site infection risk at a small university hospital in Brazil.

OBJECTIVES: To detect the occurrence of surgical-site infection (SSI) in our study sample, using the traditional variables of the National Nosocomial Infection Surveillance (NNIS) index with a locally modified cut-off point for the "T time" defining length of surgical procedure; to compare the modified and the traditional NNIS index under the hypothesis that a cut-off point discriminating procedures of short and long duration, based upon the actual experience of the study sample, can adequately predict the risk of SSI. DESIGN: A retrospective chart review of 9,322 patients undergoing surgical procedures in the period January 1993 to December 1998. SETING: A small university hospital (UH) in southern Brazil. RESULTS: The composite index using the local sample procedure-duration cut-off point (UH-index) performed better than any of the individual components of the composite index (anesthesia risk index and surgical-wound class [SWC]). The UH-index also predicted adequately the risk of SSI when compared to the traditional NNIS index, particularly when stratifying by SWC. CONCLUSIONS: A modified NNIS index, using the sample cut-off point, can adequately predict the risk of SSI in a given population. Further studies are needed to compare and validate the NNIS index of risk for populations other than those of the NNIS-participating hospitals. Larger samples using different hospitals with similar characteristics are needed to investigate the risk of SSI associated with specific operations.     

神经外科患者手术部位感染回顾性调查分析

目的探讨神经外科患者手术部位感染(SSI)的特点及危险因素,为进一步防控SSI提供理论依据。方法采用回顾性调查方法,收集2015年1—12月某院神经外科收治患者病例资料,分析患者SSI情况及其危险因素。结果神经外科手术患者715例,发生SSI 40例,发生率为5.59%。脑血管术后患者SSI发生率为7.69%,居首位;其次是颅脑肿瘤,发生率为5.94%。40例SSI患者均为器官腔隙/颅内感染。不同手术类型、手术时间、住院时间、NNIS评分患者SSI发生率比较,差异均有统计学意义(均P0.05)。结论神经外科患者SSI发生率与手术类型、手术时间、住院时间、手术危险指数等因素有关,应采取针对性的预防措施,降低SSI发生率。     

Nosocomial infection, indices of intrinsic infection risk, and in-hospital mortality in general surgery

The objectives of this paper are to assess whether two indices of intrinsic infection risk (the SENIC and the NNIS index) predict in-hospital mortality and the attributable in-hospital mortality due to nosocomial infection in surgical patients. A prospective study on 4714 patients admitted to three hospitals has been carried out. The relative risk and its 95% confidence interval (CI) were estimated. Multiple-risk factors adjusted for odds ratios (OR) were yielded by logistic regression analysis. Overall, 119 patients (2.5%) died before hospital discharge. Both the SENIC and the NNIS indices were related to in-hospital mortality in crude data. After controlling for several variables (age, sex, ASA score, cancer, renal failure, diabetes mellitus, stay at the ICU), the SENIC index did not show any significant trend with mortality (P = 0.252), whereas the trend was significant for the NNIS index (P < 0.001). Risk of death in patients with one nosocomial infection was 7.5%, and in patients developing more than one nosocomial infection was 17.1%. After adjusting for several confounding variables, the development of an organ/space surgical site infection was significantly related to mortality (OR = 4.5, 95% CI 1.5-15.6) as was blood infection (OR = 17.3, 95% CI 3.5-87.0). The association of a surgical site infection and either a respiratory tract infection or a blood infection also increased significantly the risk of in-hospital mortality (OR = 3.3, 95% CI 1.2-8.7). In conclusion, the NNIS index is a good predictor of in-hospital mortality. Patients developing an organ/space surgical site infection and/or a blood infection have an increased risk of in-hospital mortality.     

Infections after coronary artery bypass graft surgery in Victorian hospitals--VICNISS Hospital Acquired Infection Surveillance

OBJECTIVE: To establish a surveillance program reporting surgical site infection rates after coronary artery bypass graft surgery (CABGS) in Victorian public hospitals. METHODS: The VICNISS Coordinating Centre was established in 2002 to implement and co-ordinate a standardised surveillance system for hospital-acquired infections in acute care Victorian public hospitals. Using validated definitions and methodology from the Centers for Disease Control and Prevention's National Nosocomial Infection Surveillance (NNIS) program, data on risk-adjusted surgical site infection (SSI) rates were collected and submitted to the Coordinating Centre for collation and reporting. RESULTS: Six large Melbourne metropolitan hospitals contributed data for CABGS for the period 11 November 2002 to 30 June 2004, comprising a total of 3,482 patient records. Of 3,398 complete records, the aggregate SSI rates per 100 procedures for NNIS risk category 1 and 2 were 4.4 (95% Cl 3.7-5.3) and 6.0 (95% Cl 4.5-7.8) respectively. The deep sternal SSI rates were 0.6 (95% Cl 0.4-1.3) and 0.5 (95% Cl 0.5-2.4 for patients in risk category 1 and 2 respectively. The most common pathogen identified was Staphylococcus aureus. CONCLUSION: This early data from VICNISS demonstrates similar CABGS SSI rates to those reported by NNIS in the USA, but higher than reported by the German Nosocomial Infection Surveillance System. IMPLICATIONS: The adoption of a statewide, co-ordinated surveillance program using validated internationally accepted methodologies allows hospitals to benchmark their infection rates against aggregate local and international data and to examine infection prevention interventions.