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

Surgical site infection in abdominal trauma patients: risk prediction and performance of the NNIS and SENIC indexes

BACKGROUND

The National Nosocomial Infections Surveillance (NNIS) and Efficacy of Nosocomial Infection Control (SENIC) indexes are designed to develop control strategies and to reduce morbidity and mortality rates resulting from infections in surgical patients. We sought to assess the application of these indexes in patients undergoing surgery for abdominal trauma and to develop an alternative model to predict surgical site infections (SSIs).

METHODS

We conducted a prospective cohort study between November 2000 and March 2002. The main outcome measure was SSIs. We evaluated the variables included in the NNIS and SENIC indexes and some preoperative, intraoperative and postoperative variables that could be risk factors related to the development of SSIs. We performed multivariate analyses using a forward logistic regression method. Finally, we assessed infection risk prediction, comparing the estimated probabilities with actual occurrence using the areas under the receiver operating characteristic (ROC) curves.

RESULTS

Overall, 614 patients underwent an exploratory laparotomy. Of these, 85 (13.8%) experienced deep incisional and organ/intra-abdominal SSIs. The independent variables associated with this complication were an Abdominal Trauma Index score greater than 24, abdominal contamination and admission to the intensive care unit. We proposed a model for predicting deep incisional and organ/intra-abdominal SSIs using these variables (alternative model). The areas under the ROC curves were compared using the estimated probabilities for this alternative model and for the NNIS and SENIC scores. The analysis revealed a greater area under the ROC curve for the alternative model. The NNIS and SENIC scores did not perform as well as the alternative model in patients with abdominal trauma.

CONCLUSION

The NNIS and SENIC indexes were inferior to the proposed alternative model for predicting SSIs in patients undergoing surgery for abdominal trauma.

Postoperative sepsis in the United States

OBJECTIVES

To evaluate the incidence of postoperative sepsis after elective procedures, to define surgical procedures with the greatest risk for developing sepsis, and to evaluate patient and hospital confounders.

BACKGROUND DATA

The development of sepsis after elective surgical procedures imposes a significant clinical and resource utilization burden in the United States. We evaluated the development of sepsis after elective procedures in a nationally representative patient cohort and assessed the effect of sociodemographic and hospital characteristics on the development of postoperative sepsis.

METHODS

The Nationwide inpatient sample was queried between 2002 and 2006 and patients developing sepsis after elective procedures were identified using the patient safety indicator "Postoperative Sepsis" (PSI-13). Case-mix adjusted rates were calculated by using a multivariate logistic regression model for sepsis risk and an indirect standardization method.

RESULTS

A total of 6,512,921 weighted elective surgical cases met the inclusion criteria and 78,669 cases (1.21%) developed postoperative sepsis. Case-mix adjustment for age, race, gender, hospital bed size, hospital location, hospital teaching status, and patient income demonstrated esophageal, pancreatic, and gastric procedures represented the greatest risk for the development of postoperative sepsis. Thoracic, adrenal, and hepatic operations accounted for the greatest mortality rates if sepsis developed. Increasing age, Blacks, Hispanics, and men were more likely to develop sepsis. Decreased median household income, larger hospital bed size, urban hospital location, and nonteaching status were associated with greater rates of postoperative sepsis.

CONCLUSIONS

The development of postoperative sepsis is multifactorial and procedures, most likely to develop sepsis, did not demonstrate the greatest mortality after sepsis developed. Factors associated with the development of sepsis included race, age, hospital size, hospital location, and patient income. Further evaluation of high-risk procedures, populations, and environments may assist in reducing this costly complication.

Trends in postoperative sepsis: are we improving outcomes?

BACKGROUND AND PURPOSE

Each year, as many as two million operations are complicated by surgical site infections in the United States, and surgical patients account for 30% of patients with sepsis. The purpose of this study was to determine recent trends in sepsis incidence, severity, and mortality rate after surgical procedures and to evaluate changes in the pattern of septicemia pathogens over time.

METHODS

Analysis of the 1990-2006 hospital discharge data from the Healthcare Cost and Utilization Project (HCUP) State Inpatient Databases (SID) for New Jersey. Patients >or= 18 years who developed sepsis after surgery were identified using International Classification of Diseases, Ninth Revision, Clinical Modification codes as defined by the Patient Safety Indicator "Postoperative Sepsis" developed by the Agency for Healthcare Research and Quality (AHRQ). Severe sepsis was defined as sepsis complicated by organ dysfunction.

RESULTS

A total of 1,276,451 surgery discharges (537,843 elective [42.1%] and 738,608 non-elective [57.9%] procedures) were identified. After elective surgery, 5,865 patients (1.09%) developed postoperative sepsis, of whom 2,778 (0.52%) had severe sepsis. The incidence of postoperative sepsis after elective surgery increased from 0.67% to 1.74% (p < 0.0001) and severe sepsis after elective surgery from 0.22% to 1.12% (p < 0.0001). The sepsis mortality rate for elective procedures showed no significant change over time. The proportion of severe sepsis after elective cases increased from 32.9% to 64.6% (p < 0.0002). The rates of postoperative sepsis (4.24%) and severe sepsis (2.28%) were significantly greater for non-elective than for elective procedures (p < 0.0002). Non-elective surgical procedures had a significant increase in the rates of postoperative sepsis (3.74% to 4.51%) and severe sepsis (1.79% to 3.15%) over time (p < 0.0001) with the proportion of severe sepsis increasing from 47.7% to 69.9% (p < 0.0002). The in-hospital mortality rate after non-elective surgery decreased from 37.9% to 29.8% (p < 0.0001).

CONCLUSIONS

Sepsis and death were more likely after non-elective than elective surgery. Sepsis and severe sepsis has increased significantly after elective and non-elective procedures over the last 17 years. The hospital mortality rate was reduced significantly after non-elective surgery, but no improvements were found for elective surgery patients who developed sepsis. Disparities in age, sex, and ethnicity and the development of postoperative surgical sepsis were found. Population-based studies may assist in defining temporal trends, disparities, and outcomes in sepsis not elucidated in smaller studies.

Use of the national noscomial infection surveillance system risk index for prediction of mortality: results of a 6-year postdischarge follow-up study

A positive linear trend (P<.001) between the National Noscomial Infection Surveillance system (NNIS) risk index and mortality was observed in 2,848 general surgery patients followed up 6 years after discharge. In stratified analyses, the NNIS risk index predicted mortality in patients with chronic disease (P=.007, by test for trend) but not in the remaining patients.

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.

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.

Correcting for bias when estimating the cost of hospital-acquired infection: an analysis of lower respiratory tract infections in non-surgical patients

Hospital acquired infections (HAI) are costly but many are avoidable. Evaluating prevention programmes requires data on their costs and benefits. Estimating the actual costs of HAI (a measure of the cost savings due to prevention) is difficult as HAI changes cost by extending patient length of stay, yet, length of stay is a major risk factor for HAI. This endogeneity bias can confound attempts to measure accurately the cost of HAI. We propose a two-stage instrumental variables estimation strategy that explicitly controls for the endogeneity between risk of HAI and length of stay. We find that a 10% reduction in ex ante risk of HAI results in an expected savings of pound 693 ($ US 984).

Awareness of surgical site infections for advanced practice nurses

A primary concern in healthcare today is the prevention of infection. Surgical site infections (SSIs) are the leading type of infection among hospitalized patients. Advanced practice nurses play a vital role in patient care, and those who incorporate best practice standards can reduce the morbidity and mortality associated with SSIs. The Centers for Disease Control and Prevention have published recommendations for prevention of SSIs. This article reviews current literature regarding the prevention of SSIs and how critical care practitioners can incorporate these scientifically tested recommendations into their practice.

[Prevalance of nosocomial infections in tetraplegic upper extremity surgery. Prospective study of twenty patients]

INTRODUCTION

Many risk factors of nosocomial infection may be met with tetraplegic patients. The objective of this work was to study the prevalence of colonization by 3 multiresistants bacteria (methicillin resistant staphylococcus aureus (MRSA), Klebsiella pneumoniae with widened spectrum beta lactamase or multi-resistant Acinetobacter baumannii) on this population.

MATERIAL AND METHODS

It was about a prospective study for which we included 20 consecutive patients coming from a rehabilitation of long stay center to have a surgical operation of palliative reanimation of the upper limb. For each patient, the first morning of his hospitalization, many sites cultures were carried out for bacteriological analysis whose results were returned in 48 h to the operator. No patient was excluded.

RESULTS

Five patients (25%) showed the presence of SARM. One patient (5%) showed the presence of Klebsiela pneumoniae. One of the patients carrying a SARM was also carrying Acinetobacter baumannii. Overall 6 patients were contaminated (30%) but no postoperative infection occurred, neither at the time of the hospitalization nor after the exit of the service.

DISCUSSION

The various risk factors of nosocomial infection appearance met in tetraplegic patient were analyzed. This study showed that the cares of tetraplegic patients limited to the maximum the risk of nosocomial infection appearance (no one in this series) in spite of an important contamination met in this type of population which presents long durations of hospitalization, main risk factor regularly met.