Lincolnshire Knowledge and Resource Service Literature Searching

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1 Enquiry: Lincolnshire Knowledge and Resource Service Literature Searching I've been asked to benchmark the post-op spinal infection rates of one of our providers, can you support me with a rapid evidence search for this. Specifically I want to know; what is an expected/acceptable rate of post-op infections post spinal surgery in the UK and/or internationally how many of these infections could be considered 'minor', 'intermediate' or 'severe'. If data provides a rate that'd be great. how many of these infections require re-admission to hospital Completed by: 13 Alison Price, 6 th March 2013 Health Protection Agency Surgical Site Infection Surveillance Programme ceprogramme/ Information from the Surveillance Methodology pages Definition of Surgical Site Infection Another important element to consider when comparing infection rates is the definition of infection. SSISS uses a modified version of the definition described by the Centres for Disease Control in SSI are classified as incisional; superficial or deep; or organ/space infection and the definitions can be found in section 3 of the surveillance protocol. Training is given in applying these definitions during training days. Wound Class Surgical wounds can be classified according to the likelihood and degree of wound contamination at the time of the operation. The wound classification used for this surveillance is based on that developed by the National Research Council in the USA. These are detailed on page 34 of the surveillance protocol.

2 Surveillance of Surgical Site Infections in NHS hospitals in England 2011/12 Publication date: December 2012 This report is a summary of data on surgical site infections (SSIs) collected by NHS hospitals and independent sector NHS treatment centres in England participating in one of 17 surgical categories of surveillance between April 2007 and March Full text attached, extracts below: 1.5 Analyses presented in this report Data for this report were extracted on 27th September Data collected between April 2004 and March 2012 by participating NHS hospitals and independent sector NHS Treatment Centres were included. To evaluate trends, data across this entire period were analysed. For benchmarking purposes, five-year cumulative data were used (April 2007 to March 2012), whereas data for April 2011 to March 2012 were used to describe recent activity. The cumulative incidence of SSI, or the rate of SSI (%), presented in this report is based on SSIs detected during hospital stay combined with SSIs identified on readmission following the initial operation. Where appropriate, inpatient SSIs are analysed separately for meaningful interpretation. To take into account the variation in the length of follow-up during the hospital stay, the incidence density was calculated using the total number of days of patient follow-up in the denominator giving the number of SSIs per 1,000 patient days of follow-up. 1.4 Changes to surgical categories under surveillance Changes were made to the following categories during the period covered by this report: Spinal surgery was introduced in July After excluding eight categories with a small number of participating hospitals (<10), the proportion of hospitals undertaking continuous surveillance in 2011/12 was highest in hip prosthesis and knee prosthesis at 55% and 52% respectively representing an increase from the previous year. For coronary artery bypass graft (CABG) and repair of neck of femur, the proportion was 46%. This was followed by spinal surgery, reduction of long bone fracture and large bowel surgery at just over 40%. The remaining categories (vascular and abdominal hysterectomy) achieved <25%. The proportion of procedures that were revisions was generally low, with the highest observed in hip prosthesis (10%) and spinal surgery (8%). The proportion of inpatient SSIs that were classed as superficial varied by surgical category ranging from 40% in spinal surgery to 72% in knee prosthesis surgery. The observed proportions will be affected by the differences in the length of post-operative hospital stay between categories. Tables include: Table 3: SSI incidence by surgical category, all NHS hospitals in England, April March 2012 Table 4: Cumulative incidence of SSIs stratified by risk factor, by surgical factor, NHS hospital in England 2011/12

3 Health Protection Agency - National aggregated data on Surgical Site Infections Surgical Site Infection - National aggregated data on Surgical Site Infections based on hospitals that have participated in Surgical Site Infection Surveillance Service (SSISS) between April 2006 and March SSI benchmarks are based on inpatient SSIs combined with readmission SSIs to reflect the formal introduction of post-discharge surveillance from July The benchmark for surgical categories already established prior to 2008 will include historical data on readmission SSIs collected on a voluntary basis. Type of SSI by surgical category, NHS hospitals in England, April March 2011 Health Protection Agency, 2011 Superficial SSI Deep SSI Organ-space SSI All SSI types Surgical category No. %** No. %** No. %** No. Abdominal hysterrectomy Bile duct, liver and pancreatic surgery Breast Cardiac (non-cabg) Cholecystectomy Coronary artery bypass graft Cranial Gastric surgery Hip prosthesis Knee prosthesis Large bowel Limb amputation Reduction of long bone fracture Repair of neck of femur Small bowel Spinal Vascular *inpatient and readmission cases from April 2010; from July 2008 **due to rounding of individual proportions, the row-wise total percentage may not add up to exactly 100% NB: information on SSI type was available for 99.8% of the inpatient and readmssion cases; great care must be taken when interpreting data on SSI types for categories with very small number of cases overall ologicaldata/nationalaggregateddata/ssi04surgicalcategoryandtypeofincision/ Spreadsheet data by Hospital Trust

4 Cumulative incidence of SSI by surgical category, NHS hospitals in England, April March 2011 Health Protection Agency, 2011 Surgical site infections Surgical category No. No. participating operations hospitals Median length of hospital stay (days) No. Inpatient No & Inpatient readmission Rate (%) - inpatient & readmission 95% 95% LCL UCL Abdominal hysterrectomy 5, Bile duct, liver and 1,559 pancreatic surgery Breast* 1, Cardiac (non- CABG)* 1, Cholecystectomy Coronary artery bypass graft 26, , Cranial* Gastric surgery 1, Hip prosthesis 150, , Knee prosthesis 162, Large bowel 13, ,205 1, Limb amputation 2, Reduction of long 7,580 bone fracture Repair of neck of femur 39, Small bowel 2, Spinal 13, Vascular 7, All categories 438, ,548 6, * from April 2010; from July 2008 NB: no adjustment for major risk factors (e.g. case-mix) has been made and the rates should therefore be interpreted with caution; 95% CIs (Confidence Intervals) = cumulative estimate (1.96 x standard error). ologicaldata/nationalaggregateddata/ssi01surgicalsiteinfectionssummarynumberofparticip a/

5 HPA SSI Surveillance Protocol Full text attached, extracts below: Infections acquired in hospital are recognised as being associated with significant morbidity. They result in extended length of hospital stay, pain, discomfort and sometimes prolonged or permanent disability. Infections of the surgical site account for approximately 14% of all hospital acquired infections (HAI), are estimated to double the length of post-operative stay in hospital and significantly increase the cost of care. The Study on the Efficacy of Nosocomial Infection Control (SENIC) showed that wellorganised surveillance and infection control programmes that included feedback of infection rates to surgeons were associated with significant reductions in surgical site infection. Similar findings were reported by Cruse and Foord External benchmarks of surgical site infection can be a powerful driver for effecting change but require effort and co-ordination to develop.a number of national SSI surveillance systems, including SSISS in England, have demonstrated significant reductions in rates of SSI in hospitals that participate in these benchmarking schemes Valid benchmarks must be based on standardised definitions and monitoring systems. The Surgical Site Infection Surveillance Service (SSISS) national co-ordinating centre serves to enhance the value of surveillance by providing high quality comparative data based on a standardised approach to data collection, analysis and interpretation. 6.7 Identification of hospitals with unusually high or low rates of SSI After the end of each surveillance period, SSISS will review the results and will contact hospitals with rates that lie above the 90th percentile or below the 10th percentile whilst taking into account some of the uncertainties arising from the data due to small numbers Hospitals with rates of SSI above the 90th percentile for all participating hospitals are designated as high outliers and are requested to investigate to identify whether there may be a problem. This should not preclude hospitals from investigating rates of SSI that whilst not above the 90th percentile are nevertheless higher than the benchmark rate All hospitals identified as outliers are contacted and asked to investigate possible reasons. Hospitals identified as low outliers are asked to investigate their methodology as poor compliance with the standard definitions may lead to a lower sensitivity of case-finding. Figure 4: Distribution of incidence of SSI (inpatient and readmission) by category of surgery (5 year data to September 2009) overleaf

6 NICE Scoping Document - Surgical site infection: prevention and treatment of surgical site infection Clinical need for the guideline Infections that occur in the wound created by an invasive surgical procedure are generally referred to as surgical site infections (SSIs). SSIs are one of the most important causes of healthcare-associated infections (HCAIs). A prevalence survey undertaken in 2006 suggested that approximately 8% of patients in hospital in the UK have an HCAI. SSIs accounted for 14% of these infections and nearly 5% of patients who had undergone a surgical procedure were found to have developed an SSI. However, prevalence studies tend to underestimate SSI because many of these infections occur after the patient has been discharged from hospital. Surveillance of surgical site infection in hospitals reported an incidence of SSI of 4.2% from the 152 hospitals that participated in the surveillance between 1997 and Appendix B: Surgical wound classification Clean: An uninfected operative wound in which no inflammation is encountered and in which the respiratory tract, alimentary, genital, or uninfected urinary tracts are not entered. Clean-contaminated: Operative wounds in which the respiratory, alimentary, genital, or urinary tract is entered under controlled conditions and without unusual contamination. Contaminated: Open, fresh, or accidental wounds; operations with major breaks in sterile technique or gross spillage from the gastrointestinal tract; and incisions in which acute, non-purulent inflammation is encountered. Dirty or infected: Old traumatic wounds with retained devitalised tissue, and those that involve existing clinical infection. (National Academy of Science 1964)

7 NHS Health Technology Assessment Programme: Bruce J, Russell EM, Mollison J, Krukowski ZH.The measurement and monitoring of surgical adverse events. Health Technol Assess 2001;5(22). Extract, Chapter 4, Surveillance and monitoring of surgical wound infection Full text attached. In 1980, Cruse and Foord reported on their 10-year prospective study of almost 63,000 wounds, and reported infection rates within their own surgical centre based on the National Research Council wound classification. Surgical wound infection was defined as the discharge of pus. The wound infection rate for clean wounds was 1 2%, clean contaminated wounds 7.7%; contaminated wounds 15.2% and dirty wounds 40%. An infection rate of clean wounds of 1 2% was deemed acceptable, but any infection rate greater than 2% for clean wounds was thought a cause for concern and investigation. Postdischarge surveillance It is well recognised that hospital rates of surgical wound infection are a gross underestimation of the true picture, and infection rates rise significantly when surveillance is extended beyond discharge. Postdischarge surveillance is, therefore, important in epidemiological terms. Estimates of wound infections that occur or manifest themselves after discharge range from 19% to 84%. The CDC recommend that surveillance should be conducted for 30 days postoperatively, although cardiac surgeons have argued this should be extended to 6 weeks, and others have claimed that the period could be shorter as they found the majority of infections developed within 2 weeks of surgery.

8 An overview of surgical site infections: aetiology, incidence and risk factors Extracts Estimating the cost of SSIs has proved to be difficult but many studies agree that additional bed occupancy is the most significant factor. A review of the incidence and economic burden of SSIs in Europe estimated that the mean length of extended stay attributable to SSIs was 9.8 days, at an average cost per day of 325. Rates of infection Infection rates in the four surgical classifications (clean, clean-contaminated, contaminated and dirty wounds) have been published in many studies but most literature refers to the work of Cruse and Foord as a benchmark for infection rates. Before the routine use of prophylactic antibiotics infection rates were 1-2% or less for clean wounds, 6-9% for cleancontaminated wounds, 13-20% for contaminated wounds and about 40% for dirty wounds. Since the introduction of routine prophylactic antibiotic use, infection rates in the most contaminated groups have reduced drastically. Infection rates in US National Nosocomial Infection Surveillance (NNIS) system hospitals were reported to be: clean 2.1%, cleancontaminated 3.3%, contaminated 6.4% and dirty 7.1%. There is, however, considerable variation in each class according to the type of surgery being performed. Surgical site infection a European perspective of incidence and economic burden David J Leaper, Harry van Goor, Jacqueline Reilly, Nicola Petrosillo, Heinrich K Geiss, Int Wound J 2004;1: This retrospective review of reported surgical site infection (SSI) rates in Europe was undertaken to obtain an estimated scale of the problem and the associated economic burden. Preliminary literature searches revealed incomplete datasets when applying the National Nosocomial Infection Surveillance System criteria. Following an expanded literature search, studies were selected according to the number of parameters reported, from those identified as critical for accurate determination of SSI rates. Forty-eight studies were analysed. None of the reviewed studies recorded all the data necessary to enable a comparative assessment of the SSI rate to be undertaken. The estimated range from selected studies analysed varied widely from 15 20% a consequence of inconsistencies in data collection methods, surveillance criteria and wide variations in the surgical procedures investigated often unspecified. SSIs contribute greatly to the economic costs of surgical procedures estimated range: E billion. The analysis suggests that the true rate of SSIs, currently unknown, is likely to have been previously under-reported. Consequently, the associated economic burden is also likely to be underestimated. A significant improvement in study design, data collection, analysis and reporting will be necessary to ensure that SSI baseline rates are more accurately assessed to enable the evaluation of future cost-effective measures. REQUEST FROM LKRS

9 Improving Risk-Adjusted Measures of Surgical Site Infection for the National Healthcare Safety Network Yi Mu, Jonathan R. Edwards, Teresa C. Horan, Sandra I. Berrios-Torres, Scott K. Fridkin Infection Control and Hospital Epidemiology,Vol. 32, No. 10 (October 2011) The National Healthcare Safety Network (NHSN) has provided simple risk adjustment of surgical site infection (SSI) rates to participating hospitals to facilitate quality improvement activities; improved risk models were developed and evaluated. Data reported to the NHSN for all operative procedures performed from January 1, 2006, through December 31, 2008, were analyzed. Only SSIs related to the primary incision site were included. A common set of patient-and hospital-specific variables were evaluated as potential SSI risk factors by univariate analysis. Some ific variables were available for inclusion. Stepwise logistic regression was used to develop the specific risk models by procedure category. Bootstrap resampling was used to validate the models, and the c-index was used to compare the predictive power of new procedure-specific risk models with that of the models with the NHSN risk index as the only variable (NHSN risk index model). From January 1, 2006, through December 31, 2008, 847 hospitals in 43 states reported a total of 849,659 procedures and 16,147 primary incisional SSIs (risk, 1.90%) among 39 operative procedure categories. Overall, the median c-index of the new procedure-specific risk was greater (0.67 [range, ]) than the median c-index of the NHSN risk index models (0.60 [range, ]); for 33 of 39 procedures, the new procedure-specific models yielded a higher c-index than did the NHSN risk index models. A set of new risk models developed using existing data elements collected through the NHSN improves predictive performance, compared with the traditional NHSN risk index stratification. Demographic Characteristics From January 1, 2006, through December 31, 2008, 847 hospitals reported to the NHSN a total of 849,659 procedures and 16,147 SSIs at the primary incision site. The overall risk of SSI was 1.90 per 100 procedures, ranging from 0.26 (THYR) to (LTP). The variability in patient and hospital characteristics for some of the main procedure-specific variables is summarized in Table 2. US Centres for Disease Control SSI Resource Surveillance of surgical site infections in European hospitals HAISSI protocol REQUEST FROM LKRS Database Search Results Follow:

10 Table of Contents Search Results 1. A methodological, systematic review of evidence-based independent risk factors for surgical site infections after spinal surgery.... page 2 2. A methodological systematic review on surgical site infections following spinal surgery: part 2: prophylactic treatments.... page 2 3. A methodological systematic review on surgical site infections following spinal surgery: part 1: risk factors.... page 3 4. What is the prevalence of MRSA colonization in elective spine cases?.... page 3 5. Surgical site infection in spinal surgery: description of surgical and patient-based risk factors for postoperative infection using administrative claims data.... page 4 6. Is surgical case order associated with increased infection rate after spine surgery?.... page 4 7. Using the spine surgical invasiveness index to identify risk of surgical site infection: a multivariate analysis.... page 5 8. Risk factors for and epidemiology of surgical site infections.... page 6 9. Incidence, prevalence, and analysis of risk factors for surgical site infection following adult spinal surgery.... page Four country healthcare associated infection prevalence survey 2006: overview of the results.... page Surgical volume and the risk of surgical site infection in community hospitals: size matters.... page Risk factors for infection after spinal surgery.... page Surgical site infection - a European perspective of incidence and economic burden.... page Postoperative wound infections of the spine.... page Morbidity and mortality associated with surgical site infections: results from the INCISO surveillance.... page Postoperative spinal wound infection: a review of 2,391 consecutive index procedures.... page Surgical wound infection rates by wound class, operative procedure, and patient risk index. National Nosocomial Infections Surveillance System.... page 10 Page 1

11 1. A methodological, systematic review of evidence-based independent risk factors for surgical site infections after spinal surgery. Citation: European Spine Journal, March 2013, vol./is. 22/3(605-15), ; (2013 Mar) Xing D; Ma JX; Ma XL; Song DH; Wang J; Chen Y; Yang Y; Zhu SW; Ma BY; Feng R OBJECTIVE: To identify the independent risk factors, based on available evidence in the literature, for patients developing surgical site infections (SSI) after spinal surgery.methods: Non-interventional studies evaluating the independent risk factors for patients developing SSI following spinal surgery were searched in Medline, Embase, Sciencedirect and OVID. The quality of the included studies was assessed by a modified quality assessment tool that had been previously designed for observational studies. The effects of studies were combined with the study quality score using a best-evidence synthesis model.results: Thirty-six observational studies involving 2,439 patients with SSI after spinal surgery were identified. The included studies covered a wide range of indications and surgical procedures. These articles were published between 1998 and According to the quality assessment criteria for included studies, 15 studies were deemed to be high-quality studies, 5 were moderate-quality studies, and 16 were low-quality studies. A total of 46 independent factors were evaluated for risk of SSI. There was strong evidence for six factors, including obesity/bmi, longer operation times, diabetes, smoking, history of previous SSI and type of surgical procedure. We also identified 8 moderate-evidence, 31 limited-evidence and 1 conflicting-evidence factors.conclusion: Although there is no conclusive evidence for why postoperative SSI occurs, these data provide evidence to guide clinicians in admitting patients who will have spinal operations and to choose an optimal prophylactic strategy. Further research is still required to evaluate the effects of these above risk factors. 2. A methodological systematic review on surgical site infections following spinal surgery: part 2: prophylactic treatments. Citation: Spine, November 2012, vol./is. 37/24( ), ; (2012 Nov 15) van Middendorp JJ; Pull ter Gunne AF; Schuetz M; Habil D; Cohen DB; Hosman AJ; van Laarhoven CJ STUDY DESIGN: A methodological systematic review.objective: To critically appraise the validity of preventive effects attributed to prophylactic treatments for surgical site infection (SSI) after spinal surgery.summary OF BACKGROUND DATA: As a result of a rapidly increasing number of spinal procedures, health care expenditure is expected to increase substantially in the foreseeable future. Administration of effective prophylactic treatments may prevent occurrence of SSIs and may thus result in lower costs. To date, however, no review appraising the methodological quality of studies evaluating prophylactic treatments for spinal SSIs has been published.methods: Contemporary studies evaluating the preventive effect of prophylactic interventions on the rate of SSI after spinal surgery were searched through the Medline and EMBASE databases (January 2001 to December 2010). References were retrieved and bias-prone study features were abstracted individually and independently by 2 authors.results: Eighteen eligible studies were identified, including 6 randomized controlled trials and 12 comparative cohort studies. Most often, antibiotic prophylaxis administration was investigated (n = 7). Included studies covered a wide variation of indications and surgical procedures. Except for 5 studies (28%), applied definitions of SSI outcomes were ambiguous. Although several important methodological aspects, including blinding of outcome assessors and attrition, were poorly reported in randomized controlled trials, these studies were far less susceptible to bias and confounding as Page 2

12 observed in nonrandomized studies. None of the 12 cohort studies adjusted for confounding by matching, stratification, or multivariate regression techniques.conclusion: Given the plethora of previously hypothesized confounding risk factors for a spinal SSI, conduct of nonrandomized comparative therapeutic studies is strongly discouraged. On the other hand, methodological safeguards, including use of standardized definitions of putative confounders and outcomes, should be considered in more detail during the design phase of a randomized trial. 3. A methodological systematic review on surgical site infections following spinal surgery: part 1: risk factors. Citation: Spine, November 2012, vol./is. 37/24( ), ; (2012 Nov 15) Pull ter Gunne AF; Hosman AJ; Cohen DB; Schuetz M; Habil D; van Laarhoven CJ; van Middendorp JJ STUDY DESIGN: A methodological systematic review.objective: To critically appraise the validity of risk factors for surgical site infection (SSI) after spinal surgery.summary OF BACKGROUND DATA: SSIs lead to higher morbidity, mortality, and increased health care costs. Understanding which factors lead to an increased risk of SSI is important for the development of prophylactic protocols to counter this risk. To date, however, no review appraising the methodological quality of studies evaluating risk factors for spinal SSIs has been published.methods: Contemporary studies identifying risk factors for SSI after spinal surgery were searched through the Medline and EMBASE databases (January 2001 to December 2010). References were retrieved and bias-prone study features were abstracted individually and independently by 2 authors.results: Twenty-four eligible studies were identified, including 9 (nested) case-control studies and 15 case series. Included studies covered wide variations of indications and surgical procedures. A total of 73 different types of factors were evaluated for the risk of an SSI of which 34 (47%) were reported to be significantly related to at least 1 study. Only the following risk factors-diabetes mellitus, obesity, and previous SSI-were confirmed more often (n = 11, 8, and 3, respectively) as a significant risk factor for an SSI than they were disproved (n = 7, 6, and 1, respectively). Various sources of heterogeneity were observed, including patient selection, selection and analysis of putative risk factors, and definitions of SSI outcomes.conclusion: There is an abundance of conflicting data on risk factors for SSI after spinal surgery. Given various sources of heterogeneity observed in observational literature, there is a paucity of solid evidence for the proof of robust risk factors. The authors recommend the introduction, validation, and use of a standardized set of strongly justified eligibility criteria and well-defined candidate risk factors and spinal SSI outcomes. 4. What is the prevalence of MRSA colonization in elective spine cases?. Citation: Clinical Orthopaedics & Related Research, October 2012, vol./is. 470/10(2684-9), X; (2012 Oct) Chen AF; Chivukula S; Jacobs LJ; Tetreault MW; Lee JY BACKGROUND: The incidence of methicillin-resistant Staphylococcus aureus (MRSA) infection is increasing. However, the prevalence of MRSA colonization among patients undergoing spine surgery is unclear.questions/purposes: We therefore (1) determined the prevalence of MRSA colonization in a population of patients scheduled for elective spine surgery; and (2) evaluated whether MRSA screening and treatment reduce the rate of early wound complications.methods: We retrospectively reviewed prospectively collected data from 1002 patients undergoing elective spine surgery in Page 3

13 2010. There were 719 primary and 283 revision surgeries. Instrumentation was used in 72.0% cases and autologous iliac crest bone graft was taken in 65.1%. Twelve patients were lost to followup; of the remaining 990 patients, 503 were screened for MRSA and 487 were not. MRSA-colonized patients were treated with mupirocin and chlorhexidine. An early wound complication was defined as wound drainage or the presence of an abscess. Patients were followed for a minimum of 3months (average, 7months; range, 3-545days).RESULTS: Of the patients undergoing elective spine surgery and screened for MRSA, 14 of 503 (2.8%) were colonized with MRSA. The rates of early wound complications were similar for patients who were screened and pretreated for MRSA (17 of 503 [3.4%]) compared with those who were not (17 of 487 [3.5%]).CONCLUSIONS: The colonization rate for MRSA in our elective spine surgery population was comparable to that in the arthroplasty literature.level OF EVIDENCE: Level III, retrospective comparative study. See the Guidelines for Authors for a complete description of levels of evidence. 5. Surgical site infection in spinal surgery: description of surgical and patient-based risk factors for postoperative infection using administrative claims data. Citation: Spine, July 2012, vol./is. 37/15(1340-5), ; (2012 Jul 1) Abdul-Jabbar A; Takemoto S; Weber MH; Hu SS; Mummaneni PV; Deviren V; Ames CP; Chou D; Weinstein PR; Burch S; Berven SH STUDY DESIGN: Retrospective analysis.objective: The objective of this study was to investigate the accuracy of using an automated approach to administrative claims data to assess the rate and risk factors for surgical site infection (SSI) in spinal procedures.summary OF BACKGROUND DATA: SSI is a major indicator of health care quality. A wide range of SSI rates have been proposed in the literature depending on clinical setting and procedure type.methods: All spinal surgeries performed at a university-affiliated tertiary-care center from July 2005 to December 2010 were identified using diagnosis-related group, current procedural terminology, and International Classification of Diseases, Ninth Revision (ICD-9) codes and were validated through chart review. Rates of SSI and associated risk factors were calculated using univariate regression analysis. Odds ratios were calculated through multivariate logistic regression.results: A total of 6628 hospital visits were identified. The cumulative incidence of SSI was 2.9%. Procedural risk factors associated with a statistically significant increase in rates of infection were the following: sacral involvement (9.6%), fusions greater than 7 levels (7.8%), fusions greater than 12 levels (10.4%), cases with an osteotomy (6.5%), operative time longer than 5 hours (5.1%), transfusions of red blood cells (5.0%), serum (7.4%), and autologous blood (4.1%). Patient-based risk factors included anemia (4.3%), diabetes mellitus (4.2%), coronary artery disease (4.7%), diagnosis of coagulopathy (7.8%), and bone or connective tissue neoplasm (5.0%).CONCLUSION: Used individually, diagnosis-related group, current procedural terminology, and ICD-9 codes cannot completely capture a patient population. Using an algorithm combining all 3 coding systems to generate both inclusion and exclusion criteria, we were able to analyze a specific population of spinal surgery patients within a high-volume medical center. Within that group, risk factors found to increase infection rates were isolated and can serve to focus hospital-wide efforts to decrease surgery-related morbidity and improve patient outcomes. 6. Is surgical case order associated with increased infection rate after spine surgery?. Citation: Spine, June 2012, vol./is. 37/13(1170-4), ; (2012 Jun 1) Gruskay J; Kepler C; Smith J; Radcliff K; Vaccaro A Page 4

14 STUDY DESIGN: Retrospective database review.objective: To determine whether surgical site infections are associated with case order in spinal surgery.summary OF BACKGROUND DATA: Postoperative wound infection is the most common complication after spinal surgery, with incidence varying from 0.5% to 20%. The addition of instrumentation, use of preoperative prophylactic antibiotics, length of procedure, and intraoperative blood loss have all been found to influence infection rate. No previous study has attempted to correlate case order with infection risk after surgery.methods: A total of 6666 spine surgery cases occurring between January 2005 and December 2009 were studied. Subjects were classified into 2 categories: fusion and decompression. Case order was determined, with each procedure labeled 1 to 5 depending on the number of previous cases in the room. Variables such as the American Society of Anesthesiologists score, number of operative levels, wound class, age, sex, and length of surgery were also tracked. A step-down binary regression was used to analyze each variable as a potential risk factor for infection.results: Decompression cases had a 2.4% incidence of infection. Longer surgical time and higher case order were found to be significant risk factors for lumbar decompressions. Fusion cases had a 3.5% incidence of infection. Posterior approach and revision cases were significant risk factors for infection in cervical cases. For lumbar fusion cases, longer surgical time, higher American Society of Anesthesiologists score, and older age were all significant risk factors for infection.conclusion: Decompressive procedures performed later in the day carry a higher risk for postoperative infection. No similar trend was shown for fusion procedures. Our results identify potential modifiable risk factors contributing to infection rates in spinal procedures. Specific risk factors, although not defined in this study, might be related to contamination of the operating room, cross-contamination between health care providers during the course of the day, use of flash sterilization, and mid-day shift changes. 7. Using the spine surgical invasiveness index to identify risk of surgical site infection: a multivariate analysis. Citation: Journal of Bone & Joint Surgery - American Volume, February 2012, vol./is. 94/4(335-42), (2012 Feb 15) Cizik AM; Lee MJ; Martin BI; Bransford RJ; Bellabarba C; Chapman JR; Mirza SK BACKGROUND: Surgical site infection after spine surgery is a well-known complication that can result in poor outcomes, arthrodesis-site nonunion, and neurological injury. We hypothesized that a higher surgical invasiveness score will increase the risk for surgical site infection following spine surgery.methods: Data were examined from patients undergoing any type of spinal surgery from January 1, 2003, to December 31, 2004, at two academic hospitals. The surgical invasiveness index is a previously validated instrument that accounts for the number of vertebral levels decompressed, arthrodesed, or instrumented as well as the surgical approach. Relative risks and 95% confidence intervals were calculated for each of the categorical variables. Multivariate binomial stepwise logistic regression was used to examine the association between surgical invasiveness and surgical site infection requiring a return to the operating room for treatment, adjusting for confounding risk factors.results: The regression analysis of 1532 patients who were evaluated for surgical site infection identified the following significant risk factors for surgical site infection: a body mass index of >35 (relative risk, 2.24 [95% confidence interval, 1.21 to 3.86]; p = 0.01), hypertension (relative risk, 1.73 [95% confidence interval, 1.05 to 2.85]; p = 0.03), thoracic surgery versus cervical surgery (relative risk, 2.57 [95% confidence interval, 1.20 to 5.60]; p = 0.01), lumbosacral surgery versus cervical surgery (relative risk, 2.03 [95% confidence interval, 1.10 to 4.05]; p = 0.02), and a surgical invasiveness index of >21 (relative risk, 3.15 [95% confidence interval, 1.37 to 6.99]; p = 0.01).CONCLUSIONS: Patients undergoing more invasive spine surgery as measured with the surgical invasiveness index had greater risk Page 5

15 for having a surgical site infection that required a return to the operating room for treatment. Surgical invasiveness was the strongest risk factor for surgical site infection, even after adjusting for medical comorbidities, age, and other known risk factors. The magnitude of this association should be considered during surgical decision-making and intraoperative and postoperative care of the patient. These findings further validate the importance of the invasiveness index when performing safety and clinical outcome comparisons for spine surgery. 8. Risk factors for and epidemiology of surgical site infections. Citation: Surgical Infections, June 2010, vol./is. 11/3(283-7), ; (2010 Jun) Leaper DJ BACKGROUND: Surgical site infection (SSI) continues to be a major complication following operations. Identification of the frequency, the causative organisms, and the risk factors for infection still requires better definition.methods: Review of the current surgical literature was undertaken to define the epidemiology and risk factors associated with SSI.RESULTS: The rates of SSI continue to be reported with great variability, even for the same operation. Variable classification and definitions, inconsistent auditing, and an increase in post-discharge identification of infection are partially responsible for this variation. Understanding the role of the bacterial inocula and the response of the host leads to better utilization of preventive antibiotics and enhancement of host responsiveness (e.g., tissue warming). Better applications and studies of topical antiseptics need to be undertaken because of their long history of proved value.conclusions: With a better understanding of the risk factors and epidemiology, effective preventive strategies can be utilized to reduce the current rates of SSI. ; Review 9. Incidence, prevalence, and analysis of risk factors for surgical site infection following adult spinal surgery. Citation: Spine, June 2009, vol./is. 34/13(1422-8), ; (2009 Jun 1) Pull ter Gunne AF; Cohen DB STUDY DESIGN: A retrospective cohort study to identify rates and analyze the risk factors for postoperative spinal wound infection.objective: To determine significant risk factors for postoperative spinal wound infection by comparing those patients who developed a postoperative wound infection with the rest of the cohort.summary OF BACKGROUND DATA: A surgical site infection (SSI) is a common complication after spinal surgery. SSI leads to higher morbidity, mortality, and healthcare costs. To develop strategies to reduce the risk for SSI, independent risk factors for SSI should be identified.methods: The electronic patient record of all 3174 patients who underwent orthopedic spinal surgery at out institution were abstracted. Individual patient and perioperative characteristics were stored in an electronic database.results: In total, 132 (4.2%) patients were found to have an SSI with 84 having deep based infection. Estimated blood loss over 1 liter (P = 0.017), previous SSI (P = 0.012) and diabetes (P = 0.050) were found to be independent statistically significant risk factors for SSI. Obesity (P = 0.009) was found to significantly increase the risk of superficial infection, whereas anterior spinal approach decreased the risk (P = 0.010). Diabetes (P = 0.033), obesity (P = 0.047), previous SSI (P = 0.009), and longer surgeries (2-5 hours [P = 0.023] and 5 or more hours [P = 0.009]) were found to be independent significant risk factors for deep SSI.CONCLUSION: SSI is commonly seen after spinal surgery. In our study, we identified independent risk factors for both deep and superficial SSI. Identification of Page 6

16 these risk factors should allow us to design protocols to decrease the risk of SSE in future patients. ; Research Support, Non-U.S. Gov't 10. Four country healthcare associated infection prevalence survey 2006: overview of the results. Citation: Journal of Hospital Infection, July 2008, vol./is. 69/3(230-48), ; (2008 Jul) Smyth ET; McIlvenny G; Enstone JE; Emmerson AM; Humphreys H; Fitzpatrick F; Davies E; Newcombe RG; Spencer RC; Hospital Infection Society Prevalence Survey Steering Group A survey of adult patients was conducted in February 2006 to May 2006 in acute hospitals across England, Wales, Northern Ireland and the Republic of Ireland to estimate the prevalence of healthcare-associated infections (HCAIs). A total of patients were surveyed; 5743 of these had HCAIs, giving a prevalence of 7.59% (95% confidence interval: ). HCAI prevalence in England was 8.19%, in Wales 6.35%, in Northern Ireland 5.43% and in the Republic of Ireland 4.89%. The most common HCAI system infections were gastrointestinal (20.6% of all HCAI), urinary tract (19.9%), surgical site (14.5%), pneumonia (14.1%), skin and soft tissue (10.4%) and primary bloodstream (7.0%). Prevalence of MRSA was 1.15% with MRSA being the causative organism in 15.8% of all system infections. Prevalence of Clostridium difficile was 1.21%. This was the largest HCAI prevalence survey ever performed in the four countries. The methodology and organisation used is a template for future HCAI surveillance initiatives, nationally, locally or at unit level. Information obtained from this survey will contribute to the prioritisation of resources and help to inform Departments of Health, hospitals and other relevant bodies in the continuing effort to reduce HCAI. ; Research Support, Non-U.S. Gov't 11. Surgical volume and the risk of surgical site infection in community hospitals: size matters. Citation: Annals of Surgery, February 2008, vol./is. 247/2(343-9), ; (2008 Feb) Anderson DJ; Hartwig MG; Pappas T; Sexton DJ; Kanafani ZA; Auten G; Kaye KS OBJECTIVE: To determine if surgical volume affects the risk of surgical site infections (SSI) in community hospitals.background: The utility of public reporting and the optimal methods to employ when reporting SSI rates remain controversial and contentious issues. Studies examining the association between surgical volume and SSI risk have included few community hospitals and have reported conflicting results.methods: A prospective study of surgical procedures performed at 18 community hospitals from January 1, 2004 to December 31, 2005, was performed. Hospitals were separated based on average surgical volume per year: small (<1500 procedures), medium (1500 < or = procedures < 4000), and large (> or =4000 procedures). The risk of SSI for each category was determined using multivariable Poisson regression.results: Prospective surveillance identified 1434 SSIs after 132,111 surgical procedures (prevalence rate = 1.09/100 procedures). In unadjusted analysis, the risk of SSI was almost twice as high at small hospitals [prevalence rate ratio (PRR) = 1.9 (95% CI )] and large hospitals [PRR = 1.79 (95% CI )] compared with medium hospitals. After adjusting for differences between hospital category and important confounders, the risk of SSI at small hospitals was still 1.5 times higher than medium hospitals [adjusted PRR = 1.49 (95% CI )], whereas the risk at large hospitals was substantially decreased compared with medium hospitals [adjusted PRR = 1.29 (95% CI )].OUTCOMES: The relationship between Page 7

17 hospital surgical volume and rates of SSI in community hospitals is important and complex. As public reporting of SSI rates expands, improved methods for risk-adjusting infection rates are needed. Comparative Study; ; Multicenter Study; Research Support, Non-U.S. Gov't 12. Risk factors for infection after spinal surgery. Citation: Spine, June 2005, vol./is. 30/12(1460-5), ; (2005 Jun 15) Fang A; Hu SS; Endres N; Bradford DS STUDY DESIGN: A retrospective case control analysis of 48 cases of postoperative infection following spinal procedures.objectives: Spinal procedures that became infected after surgery were analyzed to identify the significance of preoperative and intraoperative risk factors. Characterization of the nature and timing of the infections was also performed.summary OF BACKGROUND DATA: The rate of postoperative infection following spinal surgery varies widely depending on the nature of the procedure and the patient's diagnosis. Preoperative comorbidities and risk factors also influence the likelihood of infection.methods: A review of 1629 procedures performed on 1095 patients revealed that a postoperative infection developed in 48 patients (4.4%). Data regarding preoperative and intraoperative risk factors were gathered from patient charts for these and a randomly selected control group of 95 uninfected patients. For analysis, these patient groups were further divided into adult and pediatric subgroups, with an age cutoff of 18 years. Preoperative risk factors reviewed included smoking, diabetes, previous surgery, previous infection, steroid use, body mass index, and alcohol abuse. Intraoperative factors reviewed included staging of procedures, estimated blood loss, operating time, and use of allograft or instrumentation.results: The majority of infections occurred during the early postoperative period (less than 3 months). Age >60 years, smoking, diabetes, previous surgical infection, increased body mass index, and alcohol abuse were statistically significant preoperative risk factors. The most likely procedure to be complicated by an infection was a combined anterior/posterior spinal fusion performed in a staged manner under separate anesthesia. Infections were primarily monomicrobial, although 5 patients had more than 4 organisms identified. The most common organism cultured from the wounds was Staphylococcus aureus. All patients were treated with surgical irrigation and debridement, and appropriate antibiotics to treat the cultured organism.conclusions: Aggressive treatment of patients undergoing complex or prolonged spinal procedures is essential to prevent and treat infections. Understanding a patient's preoperative risk factors may help the physician to optimize a patient's preoperative condition. Additionally, awareness of critical intraoperative parameters will help to optimize surgical treatment. It may be appropriate to increase the duration of prophylactic antibiotics or implement other measures to decrease the incidence of infection for high risk patients. 13. Surgical site infection - a European perspective of incidence and economic burden. Citation: International Wound Journal, December 2004, vol./is. 1/4(247-73), ; (2004 Dec) Leaper DJ; van Goor H; Reilly J; Petrosillo N; Geiss HK; Torres AJ; Berger A This retrospective review of reported surgical site infection (SSI) rates in Europe was undertaken to obtain an estimated scale of the problem and the associated economic burden. Preliminary literature searches revealed incomplete datasets when applying the National Nosocomial Infection Surveillance System criteria. Following an expanded Page 8

18 literature search, studies were selected according to the number of parameters reported, from those identified as critical for accurate determination of SSI rates. Forty-eight studies were analysed. None of the reviewed studies recorded all the data necessary to enable a comparative assessment of the SSI rate to be undertaken. The estimated range from selected studies analysed varied widely from % - a consequence of inconsistencies in data collection methods, surveillance criteria and wide variations in the surgical procedures investigated - often unspecified. SSIs contribute greatly to the economic costs of surgical procedures - estimated range: billion Euro dollars. The analysis suggests that the true rate of SSIs, currently unknown, is likely to have been previously under-reported. Consequently, the associated economic burden is also likely to be underestimated. A significant improvement in study design, data collection, analysis and reporting will be necessary to ensure that SSI baseline rates are more accurately assessed to enable the evaluation of future cost-effective measures. Comparative Study; ; Multicenter Study 14. Postoperative wound infections of the spine. Citation: Neurosurgical Focus, September 2003, vol./is. 15/3(E14), ; (2003 Sep 15) Beiner JM; Grauer J; Kwon BK; Vaccaro AR Postoperative spinal wound infections occur in 1 to 12% of patients. The rate of infection is related to the type and duration of the procedure, comorbidities, nutritional status, and various other risk factors. Antibiotic prophylactic therapy has been clearly shown to decrease the rate of infection dramatically after lumbar surgery. These infections typically manifest with signs and symptoms of wound swelling, erythema, and drainage. Laboratory-detected values such as the erythrocyte sedimentation rate and C-reactive protein can be elevated beyond what is normal for the uncomplicated postoperative course following lumbar surgery, and combined with the clinical symptoms should alert the physician to the possibility of infection. When detected, these infections should be managed aggressively with operative debridment and irrigation, including the deep subfascial layer in all cases except those with clearly demarcated superficial infection. The choice of one versus multiple debridments can be made based on the appearance of the wound, patient factors, and nutritional status. Hardware and incorporated bone graft can be left in place in the majority of cases, adding to stability. Outcomes following aggressive treatment of this complication can be excellent, with no long-term loss of function and complete eradication of the infection. ; Review 15. Morbidity and mortality associated with surgical site infections: results from the INCISO surveillance. Citation: Journal of Hospital Infection, August 2001, vol./is. 48/4(267-74), ; (2001 Aug) Astagneau P; Rioux C; Golliot F; Brucker G; INCISO Network Study Group Since 1997, a surgical-site infections (SSI) surveillance network (INCISO) has been implemented in volunteer general surgical units in Northern France. For three months each year, all patients who undergo a surgical procedure are consecutively reviewed for their peri-operative condition and traced for outcome with a 30-day follow-up. Of the surgical patients included over a three-year period, 1344 (3.4%) developed SSI and 568 died (1.5%) including 78 with an SSI. Organ-space and deep incisional SSI were associated with a higher mortality and required re-operation more frequently than did superficial incisional SSI. SSI incidence and mortality varied according to the surgical procedure. SSI was a significant predictor of mortality, independently of NNIS risk index Page 9