Risk-adjusted infection rates in surgery: a model for outcome measurement in hospitals developing new quality improvement programmes

Applications of Electrospun Drug-Eluting Nanofibers in Wound Healing: Current and Future Perspectives

Wounds are a consequence of disruption in the structure, integrity, or function of the skin or tissue. Once a wound is formed following mechanical or chemical damage, the process of wound healing is initiated, which involves a series of chemical signaling and cellular mechanisms that lead to regeneration and/or repair. Disruption in the healing process may result in complications; therefore, interventions to accelerate wound healing are essential. In addition to mechanical support provided by sutures and traditional wound dressings, therapeutic agents play a major role in accelerating wound healing. The medicines known to improve the rate and extent of wound healing include antibacterial, anti-inflammatory, and proliferation enhancing agents. Nonetheless, the development of these agents into eluting nanofibers presents the possibility of fabricating wound dressings and sutures that provide mechanical support with the added advantage of local delivery of therapeutic agents to the site of injury. Herein, the process of wound healing, complications of wound healing, and current practices in wound healing acceleration are highlighted. Furthermore, the potential role of drug-eluting nanofibers in wound management is discussed, and lastly, the economic implications of wounds as well as future perspectives in applying fiber electrospinning in the design of wound dressings and sutures are considered and reported.

Underreporting of Secondary Endpoints in Randomized Trials: Cross-sectional, Observational Study

OBJECTIVE

To determine if underreporting of secondary endpoints in randomized controlled trials occurs, using surgical site infection (SSI) as an example.

BACKGROUND

SSI is a commonly measured endpoint in surgical trials and can act as a proxy marker for primary and secondary endpoint assessments across trials in a range of medical specialties.

METHODS

Cross-sectional observational study of randomized trials including patients undergoing gastrointestinal surgery published in a representative selection of general medical and general surgical journals. Studies were included if SSI assessment was a prespecified endpoint. Adjusted binary logistic regression was used to identify factors associated with a high rate of SSI detection (≥10%).

RESULTS

From 216 trials including 45,633 patients, the pooled SSI rate was 7.7% (3519/45,633), which was significantly higher when assessed as a primary endpoint (12.6%, 1993/15,861, 49 studies) vs as a secondary endpoint (5.1%, 1526/29,772, 167 studies, P < 0.001). When assessed as a secondary outcome, standardized definitions and formal clinical reviews were used significantly less often. When adjusted for surgical contamination and methodological confounders, secondary assessment was associated with reduced SSI detection compared with primary assessment (adjusted odds ratio 0.24, 95% confidence interval 0.08-0.69, P = 0.008).

CONCLUSIONS

Secondary endpoint assessment of SSI in randomized trials was associated with significantly reduced rigor and subsequent detection rates compared with assessment as a primary endpoint. Trial investigators should ensure that primary and secondary endpoint assessments are equally robust. PRISMA guidelines should be updated to promote the conduct of meta-analysis based only on primary outcomes from randomized controlled trials.

Prospective Surveillance for Surgical Site Infection in St. Petersburg, Russian Federation

Objective.

To assess the risk-adjusted incidence and predictors of surgical site infections (SSIs).

Design.

Prospective, multicenter, observational cohort study.

Setting.

Seven surgical departments at 3 urban academic hospitals in St. Petersburg, Russian Federation.

Patients.

All patients had surgery performed between January 15 and May 12, 2000. A total of 1,453 surgical procedures were followed up. Medical records were unavailable for less than 3% of all patients; patients were not excluded for any other reason. The mean patient age was 49.3 years, 61% were female, and 34% had an American Society of Anesthesiologists physical status classification (hereafter, “ASA classification”) of at least 3. Surgery for 45% of the patients was emergent.

Results.

In all, 138 patients (9.5%) developed SSI, for a rate that was approximately 3.5 times the risk-stratified rates in the United States. Male sex (odds ratio [OR], 1.54), ASA classifications of 3 (OR, 3.7) or 4 (OR, 5.0), longer duration of surgery (OR, 2.2), and wound classes of 3 (OR, 5.5) or 4 (OR, 14.3) were associated with increased SSI risk in multivariate analysis. Endoscopic surgery was associated with a lower risk of SSI (OR, 0.23). Antibiotic prophylaxis was used in 0%-33% of operations, and 69% of uninfected patients received antibiotics after the operation.

Conclusions.

The SSI rates are significantly higher than previously reported. Although this finding may be attributable to inadequate antibiotic prophylaxis, local infection control and surgical practices may also be contributors. Use of antibiotic prophylaxis should be encouraged and the effect of local practices further investigated. Active SSI surveillance should be expanded to other parts of the Russian Federation.

Standardized Infection Ratios for Three General Surgery Procedures: A Comparison Between Spanish Hospitals and U.S. Centers Participating in the National Nosocomial Infections Surveillance System

Objectives:

To compare Spanish surgical wound infection (SWI) rates for three procedures with those published by the U.S. NNIS System, and to analyze quarterly trends.

Design:

This was a 4-year prospective analysis of SWI using data from a Spanish nosocomial infection surveillance network based on CDC classification criteria. SWI rates were computed as standardized infection ratios (SIRs). Trends for both SWIs and SIRs were evaluated by linear regression.

Setting:

Forty-three Spanish hospitals during 1997 through 2000.

Patients:

Those undergoing cholecystectomy (n = 7,631), appendectomy (n = 5,780), and herniorrhaphy (n = 9,864).

Results:

For cholecystectomy patients, the SWI rate was 4.38% and the SIR was 3.32. Both of these variables showed a slightly rising, although nonsignificant, linear trend during the study period. For appendectomy patients, the SWI rate was 7.94% and the SIR was 2.86. The linear trend was increasing for both, but only the SWI rate attained significance. For herniorrhaphy patients, the SWI rate was 1.77% and the SIR was 1.64. Both of these variables showed a significant descending tendency during the 4 years.

Conclusions:

Because the SIR takes into account the patient risk category, it is the best indicator of the trend shown by the SWI rate over time for a given surgical procedure. According to our comparison of SIRs with reference NNIS System values, SWI rates for cholecystectomy and appendectomy were high. Monitoring of the SIR will provide a basis for the design of infection control measures and the assessment of their effectiveness.

Surgical site infections: might a longer locally defined T time affect the benchmarking?

BACKGROUND

A local surgical site infection surveillance system (LS System) was established in 1998 at our teaching hospital. The aims of this article were to compare locally defined cut-points with the NNIS System T times, and to evaluate the effectiveness of different cut-points in identifying procedures at high risk for infection.

METHODS

The LS System T times were compared to those reported by the NNIS System. Procedures and surgical site infections (SSIs) were stratified according to two infection risk index (IRI) scores calculated by using the two cut-points. The effectiveness of the two IRI scores in predicting SSIs was assessed by receiver operating characteristic (ROC) analysis.

RESULTS

We have found a longer T time in three procedures categories compared to those reported by the NNIS System (GAST, OGIT, and XLAP). The LS System risk index predicted SSIs better than did the NNIS System risk index only in other digestive category, with areas under ROC curve: being, respectively of 71.1% (95% CI, 60.9, 81.3) and 63.1% (95% CI, 54.0, 72.2).

CONCLUSIONS

The use of the NNIS System T time is suitable in our local SSI surveillance system because it does not significantly affect the benchmarking.

Nine-year downward trends in surgical site infection rate in southeast France (1995–2003)

The aim of this study was to estimate temporal trends in the incidence of surgical site infection (SSI) using a large SSI surveillance network in southeast France from 1995 to 2003. Data were analysed from 187 surgical wards that had participated in the network for at least two years. The change in SSI rate over time was modelled using a hierarchical logistic regression model with patients clustered within surgical wards. Of the 200 207 patients selected, 3786 (1.9%) had an SSI. The nine-year trend in SSI rate estimated by an odds ratio of 0.95 (95% confidence interval 0.93-0.97) was interpreted as a 5% decrease in SSI rate per year. This decrease was constant over the study period and was observed for almost all of the different types of surgical operations (orthopaedic, gastrointestinal, urology, etc). Overall SSI rates were reduced by 45% over a period of nine years. This trend was maintained even when taking into account the heterogeneity of the surgical wards and the diversity of patient demographics over time. From this, the 5% decrease per year can be reasonably interpreted as a result of preventive measures taken by surgical wards to reduce SSIs.

Comparison of the National Surgical Site Infection surveillance data between The Netherlands and Germany: PREZIES versus KISS

As there has been increasing interest in comparing surgical site infection (SSI) rates between countries, we compared the SSI surveillance data for The Netherlands ('PREZIES') and Germany ('KISS'). Both surveillance systems have comparable protocols with many similar risk factors, including SSI definitions developed by the Centers for Disease Control and Prevention and optional postdischarge surveillance. Nine surgical procedure categories from several specialities were included, the reporting of which were similar, with respect to content and with enough data for proper comparison. Differences for the SSI data were found between PREZIES and KISS for duration of surgery, wound contamination class, American Society of Anesthesiologists physical status classification and the postoperative duration of hospitalization. A significantly higher superficial SSI rate was found for seven surgical procedures according to PREZIES and a higher deep SSI rate for five procedures. When considering only deep SSI during hospitalization, the differences in SSI rates were much smaller. Differences in intensity of postdischarge surveillance led to 34% of SSI being detected after discharge for PREZIES and 21% for KISS. In conclusion, even though similar infection surveillance protocols are used in The Netherlands and Germany, differences occurred in the implementation. Comparisons between countries are most reliable if only deep SSIs during hospitalization are taken into account, since these SSI are not affected by postdischarge surveillance and the diagnostic sensitivity for deep SSI is probably more alike between countries than for superficial SSI.

European perspective on surveillance

International comparisons yield interesting insights regarding quality of care, beyond the field of healthcare-associated infection (HAI) prevention. Therefore, the exchange of experiences of national surveillance systems should be encouraged. However, the interpretation of differences of HAI rates should be made very carefully. Differences in healthcare systems, legal and cultural aspects, as well as differences in the methods of the surveillance systems, may have an enormous influence. One of the most crucial aspects of surveillance data is their validity, therefore it would be very helpful to combine the experience of all European validation studies performed in order to develop a protocol for a meaningful and cost-effective method for performing validation studies. Meanwhile some national surveillance systems have shown their effectiveness with reductions of 24 57% for surgical site infections (SSIs) and 20 29% for HAI in ICUs. Today, mandatory public reporting is probably the most demanding problem for the national HAI surveillance systems in Europe. The exchange of experience between the European surveillance networks in this respect in particular--remains a cornerstone and will motivate further activities in the individual countries.

[Incidence of surgical site infections in the departments of orthopedics and traumatology]

BACKGROUND/AIM

Besides infections of urinary tract and pneumonias, as well as blood infections, surgical site infections (SSI) represent one of the most common localization of hospital infections. The aim of this study was to determine the incidence of SSI in the departments of orthopedics and traumatology as well as the SSI incidence in relation to the ASA score, surgical site contamination class and NNIS index.

METHODS

A prospective cohort study followed daily all the surgical patients hospitalized over 48 hours in the Institute for Orthopedic Surgery and Traumatology, Clinical Center of Serbia, as well as 30 days after the discharge, during the period betwen February 1 to July 31, 2002. The patients were examined and their diagnoses made according to the definition of hospital infections, i.e. upon clinical and/or laboratory analyses, using concurrently the ASA score, surgical site contamination class and NNIS index.

RESULTS

Out of 227 surgical patients, 60 were diagnosed with SSI during their hospitalization, while 3 of the patients developed SSI after the discharge. The incidence of SSI was 22.7% (95% CI = 17.8-27.6). In the patients with good health condition, i.e. ASA < or = 2, the incidence of SSI was 18.3% (43/235) and in those with ASA > 2, it was 47.6% (20/42) (chi2 = 17.4; p < 0.001). The incidence of SSI was 13.5% (25/185) in the clean wounds, 11.6% (5/43) in purely contaminated, while it was much higher in the contaminated 65.5%; (19/29) and soiled 70.0%; (14/20) wounds (chi2 = 67.6; p < 0.001). The incidence of SSI in relation to NNIS was 8.1% (13/161) in the patients with score 0, then 36.4% (32/88) in the patients with score 1, and 64.3% (18/28) in the patients with the scores 2 and 3 (chi2 = 57.3; p < 0.001). The patients with SSI stayed in the departments of orthopedics and traumatology approximately 1.8 times longer than the patients without SSI (t = 5.3; DF = 275; p < 0.0019.

CONCLUSION

It is important to emphasize the need for constant epidemiological surveillance of SSI and the implementation of preventive measures in Serbia.

Duration of operation as a risk factor for surgical site infection: comparison of English and US data

T times are used to categorize surgical procedures into long and short durations. They constitute a part of the US National Nosocomial Infection Surveillance (NNIS) risk index that is widely used internationally in surveillance for surgical site infections (SSIs). The objective of this study was to compare the US NNIS T times with data collected in England. The Surgical Site Infection Surveillance Service in England holds data collected by 168 hospitals in 13 categories of surgical procedures between 1997 and 2002. The 75(th) percentile and corresponding T time were calculated from English data and compared with US times. Differences in rates of SSI above and below the T times were compared. Graphical methods were used to assess the cut points that exhibited an association with risk of SSI. The results show that English and US T times were the same for all surgical categories except coronary artery bypass graft and vascular surgery, where the English T time was 4 h. The 75(th) percentile time for hip hemiarthroplasties was 40 min less than for total hip replacements (THR). Although the incidence of SSI in THR was significantly higher in operations lasting for longer than the T time (P<0.05), no association between risk of SSI and T times set at 1, 1.5 or 2 h was observed for hip hemiarthroplasties. In conclusion, operations lasting for longer than the T time were associated with a higher risk of SSI in most categories. In the hip prosthesis category, this association only applied to THR.

Rates of surgical-site infection: an international comparison

OBJECTIVES

To quantify the occurrence of surgical-site infections (SSIs) in an Italian region and to estimate the proportion of potentially avoidable infections through benchmarking comparison.

DESIGN

Prospective study during 1 month based on a convenience sample of surgical patients admitted to 31 public hospitals. All of the patients undergoing an intervention included among the 44 operative procedures of the National Nosocomial Infections Surveillance (NNIS) System were enrolled. Ninety-five percent of the patients were actively observed after discharge for up to 30 days for all of the operations and for up to 1 year for operations involving implantation.

RESULTS

Among the 6,167 operative procedures studied, 290 infections were recorded (4.7 per 100 procedures), 206 (71%) of which were SSIs (3.3 per 100 procedures; 95% confidence interval, 2.9-3.9). One hundred thirty-five SSIs (65.5%) were superficial infections, 53 (25.7%) were deep infections, and 12 (5.8%) were organ-space infections; in 6 cases (2.9%), the type of SSI was not recorded. The frequency of SSIs observed in this study was significantly higher for several procedures than that expected when the NNIS System rates (standardized infection ratio [SIR] ranging from 1.77 to 6.42) or the Hungarian rates (SIR ranging from 1.28 to 3.04) were applied to the study population.

CONCLUSIONS

The high intensity of postdischarge surveillance can in part explain the differences observed. To allow for meaningful benchmarking comparison, in addition to intrinsic patient risk, data on the intensity of postdischarge surveillance should be included in published reports.

Surgical site infections in patients undergoing major operations in a university hospital: using standardized infection ratio as a benchmarking tool

BACKGROUND

Because patterns of infection acquired in patients undergoing operation are ever changing, it is an essential part of nosocomial infection surveillance programs to periodically document the epidemiologic features of infection in these patients. This study was conducted with the primary intention of describing the incidence and risk factors of the surgical site infection (SSI).

METHODS

We performed a prospective study in patients undergoing certain major operations at a 750-bed university hospital in Thailand. The National Nosocomial Infection Surveillance (NNIS) system method and criteria were used for identifying and diagnosing infection. The infection rates were benchmarked with the NNIS report by means of indirect standardization and reported in terms of standardized infection ratio. Risk factors for SSI were evaluated using the multiple logistic regression model.

RESULTS

From September 1998 to March 2000, the study included 4193 patients with 4437 major operations. The study identified 192 SSIs, 76 urinary catheter-related urinary tract infections, 26 central line-related bloodstream infections, and 39 instances of ventilator-associated pneumonia (VAP), yielding an infection rate of 4.3 SSIs/100 operations, 11.0 catheter-related urinary tract infections/1000 urinary catheter-days, 6.1 central line-related bloodstream infections/1000 central line-days, and 11.0 VAPs/1000 ventilator-days. When compared with data from NNIS, the standardized infection ratio of SSI, catheter-related urinary tract infection, central line-related bloodstream infection, and VAP were 2.3, 2.1, 1.1, and 0.8, respectively. The factors that significantly associated with SSI were duration of operation in minutes, American Society of Anesthesiologists (ASA) class, and degree of wound contamination.

CONCLUSION

All of the infection rates identified, except VAP, were higher than the average NNIS rates. The risk factors for SSI were prolonged duration of operation, poor physical status according to ASA classification, and higher degree of wound contamination.

Monitoring antimicrobial use and resistance: comparison with a national benchmark on reducing vancomycin use and vancomycin-resistant enterococci

To determine if local monitoring data on vancomycin use directed quality improvement and decreased vancomycin use or vancomycin-resistant enterococci (VRE), we analyzed data from 50 intensive-care units (ICUs) at 20 U.S. hospitals reporting data on antimicrobial-resistant organisms and antimicrobial agent use. We compared local data with national benchmark data (aggregated from all study hospitals). After data were adjusted for changes in prevalence of methicillin-resistant Staphylococcus aureus, changes in specific prescriber practice at ICUs were associated with significant decreases in vancomycin use (mean decrease -48 defined daily doses per 1,000 patient days, p<0.001). These ICUs also reported significant decreases in VRE prevalence compared with those not using unit-specific changes in practice (mean decrease of 7.5% compared with mean increase of 5.7%, p<0.001). In this study, practice changes focused towards specific ICUs were associated with decreases in ICU vancomycin use and VRE prevalence.

Risk assessment for surgical site infections following total hip and total knee prostheses

The purpose of the study was to assess the relative importance of risk factors for surgical site infections (SSI) following total hip and total knee prostheses in The Netherlands. In the period 1996-99 63 hospitals in The Netherlands registered SSI after 36,629 orthopedic operations. Total hip and total knee prostheses were analyzed in detail. The results of our study showed that a long preoperative stay was a risk factor for deep SSIs after both procedures. A dirty or contaminated wound and a serious systemic condition were risk factors for deep SSIs after total hip prostheses. If post-discharge surveillance was carried out, more SSIs were found, for total knee prostheses more than twice as many. Independent risk factors for SSIs after total hip prostheses were a contaminated/dirty wound and for total knee prostheses a short operation duration. The authors conclude that surveillance of surgical site infections following total hip and total knee prostheses revealed different risk factors for (deep) SSIs.