Complex Surgical Site Infections Research Articles

Development of machine learning models for the detection of surgical site infections following total hip and knee arthroplasty: a multicenter cohort study

BackgroundPopulation based surveillance of surgical site infections (SSIs) requires precise case-finding strategies. We sought to develop and validate machine learning models to automate the process of complex (deep incisional/organ space) SSIs case detection.MethodsThis retrospective cohort study included adult patients (age ≥ 18 years) admitted to Calgary, Canada acute care hospitals who underwent primary total elective hip (THA) or knee (TKA) arthroplasty between Jan 1st, 2013 and Aug 31st, 2020. True SSI conditions were judged by the Alberta Health Services Infection Prevention and Control (IPC) program staff. Using the IPC cases as labels, we developed and validated nine XGBoost models to identify deep incisional SSIs, organ space SSIs and complex SSIs using administrative data, electronic medical records (EMR) free text data, and both. The performance of machine learning models was assessed by sensitivity, specificity, positive predictive value, negative predictive value, F1 score, the area under the receiver operating characteristic curve (ROC AUC) and the area under the precision–recall curve (PR AUC). In addition, a bootstrap 95% confidence interval (95% CI) was calculated.ResultsThere were 22,059 unique patients with 27,360 hospital admissions resulting in 88,351 days of hospital stay. This included 16,561 (60.5%) TKA and 10,799 (39.5%) THA procedures. There were 235 ascertained SSIs. Of them, 77 (32.8%) were superficial incisional SSIs, 57 (24.3%) were deep incisional SSIs, and 101 (42.9%) were organ space SSIs. The incidence rates were 0.37 for superficial incisional SSIs, 0.21 for deep incisional SSIs, 0.37 for organ space and 0.58 for complex SSIs per 100 surgical procedures, respectively. The optimal XGBoost models using administrative data and text data combined achieved a ROC AUC of 0.906 (95% CI 0.835–0.978), PR AUC of 0.637 (95% CI 0.528–0.746), and F1 score of 0.79 (0.67–0.90).ConclusionsOur findings suggest machine learning models derived from administrative data and EMR text data achieved high performance and can be used to automate the detection of complex SSIs.

Baseline prevalence of antimicrobial resistance in patients who develop a surgical site infection in hip and knee replacements: A brief report

Prior to clean surgeries, decolonization with topical antimicrobials may lead to an increase in antimicrobial resistance. To provide a baseline prevalence of resistance to topical antimicrobials, in Alberta, specimens were collected from surgical site infections following hip and knee replacements. Among 81 samples with complex surgical site infections, in 43 specimens Staphylococcus species were isolated. Only coagulase-negative staphylococci isolates carried resistance genes with 10 carrying the gene qac and 6 carrying the MupA gene.

Validating administrative data to identify complex surgical site infections following cardiac implantable electronic device implantation: a comparison of traditional methods and machine learning

BackgroundCardiac implantable electronic device (CIED) surgical site infections (SSIs) have been outpacing the increases in implantation of these devices. While traditional surveillance of these SSIs by infection prevention and control would likely be the most accurate, this is not practical in many centers where resources are constrained. Therefore, we explored the validity of administrative data at identifying these SSIs.MethodsWe used a cohort of all patients with CIED implantation in Calgary, Alberta where traditional surveillance was done for infections from Jan 1, 2013 to December 31, 2019. We used this infection subgroup as our “gold standard” and then utilized various combinations of administrative data to determine which best optimized the sensitivity and specificity at identifying infection. We evaluated six approaches to identifying CIED infection using administrative data, which included four algorithms using International Classification of Diseases codes and/or Canadian Classification of Health Intervention codes, and two machine learning models. A secondary objective of our study was to assess if machine learning techniques with training of logistic regression models would outperform our pre-selected codes.ResultsWe determined that all of the pre-selected algorithms performed well at identifying CIED infections but the machine learning model was able to produce the optimal method of identification with an area under the receiver operating characteristic curve (AUC) of 96.8%. The best performing pre-selected algorithm yielded an AUC of 94.6%.ConclusionsOur findings suggest that administrative data can be used to effectively identify CIED infections. While machine learning performed the most optimally, in centers with limited analytic capabilities a simpler algorithm of pre-selected codes also has excellent yield. This can be valuable for centers without traditional surveillance to follow trends in SSIs over time and identify when rates of infection are increasing. This can lead to enhanced interventions for prevention of SSIs.

Retrospective analysis of the management strategies for surgical site infection post total hip or knee arthroplasty from tertiary care centres in Edmonton, Alberta

Surgical site infection (SSI) following hip or knee arthroplasty poses a serious health and economic burden. To evaluate SSI management strategies and outcomes to help address this problem. A retrospective cohort study was undertaken of adults undergoing primary total hip or knee arthroplasty who were identified to have a complex SSI by infection prevention and control surveillance audit. Audits identified SSI within 90 days of arthroplasty. Patients at two tertiary referral centres in Edmonton, Alberta, Canada from 2012 to 2019 were included, and SSI cases were followed for 2 years. In total, 240 SSIs were identified. Of these, 202 (84%) cases were managed with debridement with antibiotics and implant retention (DAIR), of which 71% achieved cure. The use of any topical intra-operative antibiotic in DAIR was not associated with improved outcome (odds ratio 1.68, 95% confidence interval 0.91-3.10; P=0.097). DAIR performed 31-90 days after arthroplasty had a lower chance of cure compared with DAIR performed within 30 days of arthroplasty; however, this difference was not significant (60 vs 73%; P=0.123). Initial treatment failures requiring additional surgery had a 51% cure rate. The majority (78%) of treatment failures initially managed with DAIR ultimately required two-stage revision. This study provides insight from a population-based perspective into the surgical management of SSI after primary total hip or knee arthroplasty in a large cohort. Additionally, SSIs that had initial management failure were followed. These data can inform future studies, such as the economic burden associated with these infections, and may be used to plan interventions to optimize SSI management.

Surgical site infection trends in community hospitals from 2013 to 2018.

Sparse recent data are available on the epidemiology of surgical site infections (SSIs) in community hospitals. Our objective was to provide updated epidemiology data on complex SSIs in community hospitals and to characterize trends of SSI prevalence rates over time. Retrospective cohort study. SSI data were collected from patients undergoing 26 commonly performed surgical procedures at 32 community hospitals in the southeastern United States from 2013 to 2018. SSI prevalence rates were calculated for each year and were stratified by procedure and causative pathogen. Over the 6-year study period, 3,561 complex (deep incisional or organ-space) SSIs occurred following 669,467 total surgeries (prevalence rate, 0.53 infections per 100 procedures). The overall complex SSI prevalence rate did not change significantly during the study period: 0.58 of 100 procedures in 2013 versus 0.53 of 100 procedures in 2018 (prevalence rate ratio [PRR], 0.84; 95% CI, 0.66-1.08; P = .16). Methicillin-sensitive Staphylococcus aureus (MSSA) complex SSIs (n = 480, 13.5%) were more common than complex SSIs caused by methicillin-resistant S. aureus (MRSA; n = 363, 10.2%). The complex SSI rate did not decrease in our cohort of community hospitals from 2013 to 2018, which is a change from prior comparisons. The reason for this stagnation is unclear. Additional research is needed to determine the proportion of or remaining SSIs that are preventable and what measures would be effective to further reduce SSI rates.

Burden of surgical management of prosthetic joint infections following hip and knee replacements in Alberta, Canada: an analysis and comparison of two major urban centres

Complex surgical site infections (SSIs) and revisions for these infectious complications following total knee and hip arthroplasties are associated with significant economic costs. To evaluate the cost of one-stage and two-stage revisions; debridement, antibiotic, and implant retention (DAIR) and DAIR with liner exchange for complex hip or knee SSIs in Alberta, Canada. We used the Alberta Health Services Infection Prevention and Control database to identify individuals >18 years old from the two major urban centers in Alberta, Calgary, and Edmonton zone, with complex hip or knee SSIs who underwent surgical intervention between April 1, 2012, and March 31, 2019. Micro-costing and gross-costing methods were used to estimate 12 and 24-month costs following the initial hospital admission for arthroplasty. Subgroup, inverse gaussian and gamma regression analysis were used to evaluate the associations of the revision procedure, age, sex, and comorbidities on cost. A total of 382 patients with complex SSIs were identified with a mean age of 66.1 years. DAIR and DAIR with liner exchange resulted in the lowest 12- and 24-month costs at $53,197 (95% CI, $38,006 - $68,388) and $57,340 (95% CI, $48,576 - $66,105), respectively; two-stage revision was the costliest procedure. Most of the incurred costs (>98%) were accrued within the first 12 months following the initial procedure. Medical costs are highest 12 months following initial arthroplasty and for two-stage revisions in hip and knee complex SSI.

Economic burden of surgical management of surgical site infections following hip and knee replacements in Calgary, Alberta, Canada.

To evaluate the cost of 1-stage and 2-stage revisions, debridement, antibiotic and implant retention (DAIR) and DAIR with liner exchange for complex surgical site infections (SSIs) following hip and knee replacements. Retrospective population-based economic analysis of patients undergoing intervention for SSIs between April 1, 2012 and March 31, 2019. The study was conducted in the Calgary zone of Alberta Health Services (AHS) in Canada. Individuals >18 years with complex SSI following hip or knee replacement. Patients with complex SSIs were identified using the AHS infection prevention and control database. A combination of microcosting and gross costing methods were used to estimate 12- and 24-month costs following the initial hospital admission for arthroplasty. Subgroup, inverse Gaussian and γ regression analyses were used to evaluate the impact of age and comorbidities on cost. In total, 142 patients with complex SSIs were identified, with a mean age of 66.8 years. Total direct medical costs in United States dollars of 2-stage revisions were ($100,992 (95% CI, 34,587-167,396) at 12 months. The 1-stage revision ($41,176; 95% CI, 23,361-58,991), DAIR with liner exchange ($41,267; 95% CI, 29,923-52,612) and DAIR ($46,605; 95% CI, 15,277-76,844) were associated with fewer costs at 12 months. Age >65 years and chronic complications of diabetes and hypertension were associated with increased costs in subgroup and regression analysis. Medical costs are highest at 12 months and for 2-stage revisions in hip and knee complex SSI cases. Further work should explore surgical outcomes correlated with costs to enhance patient care.

A comparison of surgical site infections following total hip replacement and total knee replacement surgeries identified by Infection Prevention and Control and the National Surgical Quality Improvement Program in Alberta, Canada.

To understand how the different data collections methods of the Alberta Health Services Infection Prevention and Control Program (IPC) and the National Surgical Quality Improvement Program (NSQIP) are affecting reported rates of surgical site infections (SSIs) following total hip replacements (THRs) and total knee replacements (TKRs). Retrospective cohort study. Four hospitals in Alberta, Canada. Those with THR or TKR surgeries between September 1, 2015, and March 31, 2018. Demographic information, complex SSIs reported by IPC and NSQIP were compared and then IPC and NSQIP data were matched with percent agreement and Cohen's κ calculated. Statistical analysis was performed for age, gender and complex SSIs. A P value <.05 was considered significant. In total, 7,549 IPC and 2,037 NSQIP patients were compared. The complex SSI rate for NSQIP was higher compared to IPC (THR: 1.19 vs 0.68 [P = .147]; TKR: 0.92 vs 0.80 [P = .682]). After matching, 7 SSIs were identified by both IPC and NSQIP; 3 were identified only by IPC, and 12 were identified only by NSQIP (positive agreement, 0.48; negative agreement, 1.0; κ = 0.48). Different approaches to monitor SSIs may lead to different results and trending patterns. NSQIP reports total SSI rates that are consistently higher than IPC. If systems are compared at any point in time, confidence on the data may be eroded. Stakeholders need to be aware of these variations and education provided to facilitate an understanding of differences and a consistent approach to SSI surveillance monitoring over time.

905. Surgical Site Infections Following Colon Surgery in a Large Network of Community Hospitals

BackgroundColon surgeries are commonly performed, and surgical site infections (SSIs) following these procedures are routinely reported to the National Healthcare Safety Network (NHSN). However, the impact of infections present at the time of surgery (PATOS) and emergent surgeries on the epidemiology of colon surgery SSIs has not been well described.MethodsWe retrospectively analyzed prospectively collected data on complex (i.e., deep incisional or organ space) SSIs following colon surgery performed at 34 community hospitals in the southeastern United States from January 2015 to June 2019. We excluded SSIs categorized as PATOS. We then stratified colon surgery SSI rates according to age, sex, body mass index (BMI), operation duration, diabetes diagnosis, American Society of Anesthesiologists (ASA) physical status, wound class, emergent procedure, endoscopic procedure, and hospital colon surgery volume. Finally, we explored effect measure modification of emergent surgery and open surgery on hospital volume using log-binomial modeling and tests of homogeneity.ResultsA total of 722 complex SSIs occurred following 28,642 colon surgeries (prevalence rate [PR], 2.52 per 100 procedures). After PATOS SSIs were excluded, 545 complex SSIs remained (PR 1.90 per 100 procedures). Risk factor analysis revealed that age < 75 years and operation time > 75th percentile (188 minutes) during the 5-year study period) significantly increased risk of SSI (Table 1). The most common pathogens that caused SSIs in this study cohort were Escherichia coli, Enterococcus, and Klebsiella. (Table 2) 105 (19%) SSIs were culture-negative and 378 (69%) of the SSIs were polymicrobial. We defined hospital volume as high (>500 procedures in the 5-year period) based on the median hospital volume in the dataset. No significant effect measure modification occurred between hospital volume and either laparoscopic surgery or emergent surgery (Table 3).Table 1: Characteristics of patients who underwent colon surgery from January 2015 to June 2018 in 34 community hospitals. Table 2: Count and frequency of pathogens that caused complex surgical site infections after colon surgery Table 3: Colon surgery complex surgical site infection rates, stratified by emergent, elective, open, and laparoscopic procedures and hospital colon surgery volume ConclusionIn our cohort, we found that one-fourth of colon surgery SSIs were categorized as PATOS, which are no longer publicly reported to the Centers for Medicare & Medicaid Services. While most SSI literature describes higher volume hospitals having lower SSI rates, high colon surgery volume was associated with increased SSI rates in our community hospital cohort.Disclosures All Authors: No reported disclosures

886. Impact of Type of Surgical Management on the Incidence of Recurrent Surgical Site Infections Following Hip and Knee replacements in Calgary, Alberta

BackgroundRecurrent surgical site infections (SSIs) are associated with decreased quality of life for patients and increased economic burden to healthcare systems. Positive cultures at reimplantation and patient co-morbidities have been shown to increase the risk of recurrent SSI in hip and knee surgical site infections. Two-stage exchange has been considered for the most appropriate surgical management for these SSI’s, however, it is unclear whether the type of revision arthroplasty and pathogen of the first SSI impacts recurrence rates.MethodsA retrospective review of prospectively collected data on all complex SSIs following primary hip and knee arthroplasties between April 1 2012 and March 31, 2019, in Calgary, Alberta was performed. Patients were followed for two years post-index arthroplasty to determine initial management of first complex SSI (Debridement, antibiotics and implant retention (DAIR) vs DAIR+liner exchange vs one-stage vs two-stage), rate of recurrent complex SSI, and microbiological data for first and subsequent SSI’s.ResultsOf the 142 complex SSIs, 95 (66.9%) were managed with DAIR and liner exchange, 25 (17.6%) were managed with DAIR, 13 (9.1%) with one-stage and 8 (5.6%) with two-stage procedures. The recurrence rate was 19/95 (20%) for DAIR and liner, 8/25 (32%) for DAIR alone, 2/13 (15%) with one stage, and 3/8 (37.5%) with two-stage. There was no significant difference in recurrence rates of complex SSI when stratified by surgical management. Of the pathogens, Staphylococcus aureus (S.aureus) (including methicillin-resistant S. aureus (MRSA)) accounted for 35.2% of total first SSI and 50% of recurrences. A significantly higher proportion of S.aureus infections (including MRSA) ended up with a recurrent infection compared to all other pathogens (p=0.045). Of the 32 recurrences, 28.1% were due to the same pathogen as the initial SSI.ConclusionS.aureus was the most common pathogen causing initial and recurrent SSIs. This reinforces that S.aureus complex SSIs would likely benefit from early recognition and aggressive treatment. Recurrence of SSI was not impacted by type of revision arthroplasty. This study is limited by a small sample size. These findings contribute to the paucity of literature in this area and suggest a need for expansion to larger populations.Disclosures All Authors: No reported disclosures

Economic Analysis of the European Healthcare Burden of Sternal-Wound Infections Following Coronary Artery Bypass Graft.

Background: Sternal wound infections (SWIs) can be some of the most complex surgical-site infections (SSIs) and pose a considerable risk following coronary artery bypass graft surgery (CABG).Objective: To capture the cost burden of SWIs following CABG across European countries.Methods: We modeled a standardized care pathway for CABG, starting at the point of surgery and extending to 1-year post surgery. The Markov model captures the incidence and cost of an SWI (deep or superficial SWIs). The cost burden is calculated from a hospital perspective such that the main inputs relating to costs were intensive-care-unit (ICU) and general-ward (GW) days. Outpatient care, not in the hospital setting, has no cost in this analysis. Model input parameters were taken from Eurostat and a review of published, peer-reviewed literature. European countries were included in this analysis when values for 50% of the required input parameters per country were identified. Missing data points were interpolated from available data. The robustness of results was assessed via probabilistic sensitivity analysis.Results: Full required input data were available for 8 European countries; a further 18 countries had sufficient data for analysis. The median (interquartile range) for SWI incidence across the 26 countries was 3.9% (2.9–5.6%). The total burden for all 26 countries of SWIs after CABG was €170.8 million. These costs were made up of 25,751 additional ICU days, 137,588 additional GW days, and 7,704 readmissions. The mean cost of an SWI ranged from €8,924 in Poland to €21,321 in Denmark. Relative to the costs of post-CABG care without an SWI complication, the incremental cost of an SWI was highest in Greece (24.9% increase) and lowest in the UK (3.8% increase) with a median (interquartile range) of 12% (10–16%) across all 26 countries.Conclusions: SWIs following CABG present a considerable burden to healthcare budgets.

Validation of a Surgical Site Infection Detection Algorithm for Use in Cardiac and Orthopedic Surgery Research

Background: Studies of interventions to decrease rates of surgical site infections (SSIs) must include thousands of patients to be statistically powered to demonstrate a significant reduction. Therefore, it is important to develop methodology to extract data available in the electronic medical record (EMR) to accurately measure SSI rates. Prior studies have created tools that optimize sensitivity to prioritize chart review for infection control purposes. However, for research studies, positive predictive value (PPV) with reasonable sensitivity is preferred to limit the impact of false-positive results on the assessment of intervention effectiveness. Using information from the prior tools, we aimed to determine whether an algorithm using data available in the Veterans Affairs (VA) EMR could accurately and efficiently identify deep incisional or organ-space SSIs found in the VA Surgical Quality Improvement Program (VASQIP) data set for cardiac and orthopedic surgery patients. Methods: We conducted a retrospective cohort study of patients who underwent cardiac surgery or total joint arthroplasty (TJA) at 11 VA hospitals between January 1, 2007, and April 30, 2017. We used EMR data that were recorded in the 30 days after surgery on inflammatory markers; microbiology; antibiotics prescribed after surgery; International Classification of Diseases (ICD) and current procedural terminology (CPT) codes for reoperation for an infection related purpose; and ICD codes for mediastinitis, prosthetic joint infection, and other SSIs. These metrics were used in an algorithm to determine whether a patient had a deep or organ-space SSI. Sensitivity, specificity, PPV and negative predictive values (NPV) were calculated for accuracy of the algorithm through comparison with 30-day SSI outcomes collected by nurse chart review in the VASQIP data set. Results: Among the 11 VA hospitals, there were 18,224 cardiac surgeries and 16,592 TJA during the study period. Of these, 20,043 were evaluated by VASQIP nurses and were included in our final cohort. Of the 8,803 cardiac surgeries included, manual review identified 44 (0.50%) mediastinitis cases. Of the 11,240 TJAs, manual review identified 71 (0.63%) deep or organ-space SSIs. Our algorithm identified 32 of the mediastinitis cases (73%) and 58 of the deep or organ-space SSI cases (82%). Sensitivity, specificity, PPV, and NPV are shown in Table 1. Of the patients that our algorithm identified as having a deep or organ-space SSI, only 21% (PPV) actually had an SSI after cardiac surgery or TJA. Conclusions: Use of the algorithm can identify most complex SSIs (73%–82%), but other data are necessary to separate false-positive from true-positive cases and to improve the efficiency of case detection to support research questions.Funding: NoneDisclosures: None

Reporting Surgical Site Infections (SSIs) Using Different Surveillance Systems— Complexity of Infection Matters

Background: In Alberta, Canada, surgical site infections (SSIs) following total hip (THR) and knee replacements (TKR) are reported using 2 data sources: infection prevention and control (IPC), which surveys all THR and TKR using NHSN definitions and the Canadian International Classification of Disease, Tenth Revision (ICD-10-CA) codes, and the National Surgical Quality Improvement Program (NSQIP), which uses a systematic sampling process that involves an 8-day cycle schedule, modified NHSN definitions and current procedural terminology (CPT) codes. We compared the similarities and discrepancies in THR/TKR SSI reporting. Methods: A retrospective multisite cohort study of IPC and NSQIP THR/TKR SSI data at 4 hospitals was performed. SSI data were collected between September 1, 2015, and March 31, 2018. Demographic information and complex and total SSIs reported by IPC and NSQIP were compared for both THR and TKR surgeries. To determine whether both data sources reported similar trends over time, total SSIs by quarter were compared. Univariate analyses using a t test for age and the χ2 test for gender for complex SSIs and total SSIs was performed. The Pearson correlation and the Shapiro-Wilk test were used to assess the THR and TKR trends between the 2 data sources. A P value of &lt;.05 was considered significant. Results: Following the removal of duplicates and missing data, 7,549 IPC and 2,037 NSQIP patients, respectively, were compared. Age, gender, and other demographic parameters were not significantly different. Total THR and TKR SSIs per 100 procedures using NSQIP data were significantly higher than the same rates using IPC data: THR, 2.25 versus 0.92 (P &lt; .05) and TKR, 3.43 versus 1.26 (P &lt; .05). Both IPC and NSQIP data indicated increasing total THR SSI rates over time, but with different magnitudes (r = 0.658). For total TKR SSI, the IPC rate decreased, whereas the NSQIP rate increased over the same period (r = 0.374). When superficial SSIs were excluded, the rates reported between IPC and NSQIP data by hospital and by procedure type were more comparable, with trends toward higher rates reported by NSQIP for THR than for TKR: THR, 1.19 versus 0.68 (P = 0.15) and TKR, 0.92 versus 0.80 (P = .68). Conclusions: Different approaches used to monitor SSIs following surgeries may lead to different results and trend patterns. NSQIP reports total SSI rates that are significantly higher than the IPC Alberta orthopedic population predominantly as a result of increased identification of superficial SSIs. Because the diagnosis of superficial SSIs may be less reliable, SSI reporting should focus on complex infections.Funding: NoneDisclosures: None

Making a Case for Adjusting NHSN SSI Risk Stratification Classification for Use of Enhanced Electronic Infection Surveillance

Background: A large healthcare system in Georgia went live with an enhanced electronic infection surveillance system in August of 2018. The system was employed at its facilities using a staggered approach. Prior to the implementation of this infection surveillance platform, the healthcare system performed healthcare-associated infection (HAI) surveillance using an in-house culture-based system. The NHSN estimates that culture-based surveillance misses 50%–60% of true surgical site infections (SSIs). Due to the lack of clinical-based detection methods (eg, radiologic imaging), we were unable to appropriately detect all patient harm using the old surveillance system. Method: A retrospective analysis was performed to assess the change in HAI for colon (COLO), abdominal hysterectomy (HYST), hip prosthesis (HPRO), and knee prosthesis (KPRO). SSI cases that met NHSN surveillance criteria were reviewed to determine whether they would have been identified prior to launching the new enhanced electronic surveillance system. Results: Systemwide, 8 of 26 COLO SSIs (31%) and 9 of 18 HYST SSIs (50%) would have not been detected using our old surveillance system. HPRO SSIs and KPRO SSIs identified by our new surveillance system were detected using our old surveillance system, and no change was observed. Conclusion: This analysis showed an increase in COLO SSIs and HYST SSIs from enhanced surveillance. Electronic surveillance systems are not considered as a risk factor in the NHSN annual facility survey that aids in calculating a facility’s standardized infection ratio (SIR). These data help support NHSN consideration of modifying the logistic regression calculation used for the complex SSI models. This revision would allow facilities to compare themselves equitably to those using electronic infection surveillance.Funding: NoneDisclosures: None

Associations Between Social Risk Factors and Surgical Site Infections After Colectomy and Abdominal Hysterectomy

Surgical site infection (SSI) is an important patient safety outcome. Although social risk factors have been linked to many adverse health outcomes, it is unknown whether such factors are associated with higher rates of SSI. To determine whether social risk factors, including race/ethnicity, insurance status, and neighborhood income, are associated with higher rates of SSI after colectomy or abdominal hysterectomy, 2 surgical procedures for which SSI rates are publicly reported and included in pay-for-performance programs by Medicare and other groups. This cross-sectional study analyzed adults undergoing colectomy or abdominal hysterectomy, as captured in State Inpatient Databases for Arizona, Florida, Iowa, Massachusetts, Maryland, New York, and Vermont. Operations were performed in 2013 through 2014 at general acute care hospitals in the United States. Data analysis was conducted from October 2018 through June 2019. Colectomy or hysterectomy. Postoperative complex SSI rates. A total of 149 741 patients met the inclusion criteria, including 90 210 patients undergoing colectomies (mean [SD] age, 63.4 [15.6] years; 49 029 [54%] female; 74% white, 11% black, 9% Hispanic, and 5% other or unknown race/ethnicity) and 59 531 patients undergoing abdominal hysterectomies (mean [SD] age, 49.8 [11.8] years; 100% female; 52% white, 26% black, 14% Hispanic, and 8% other or unknown race/ethnicity). In the colectomy cohort, 34% had private insurance, 52% had Medicare, 9% had Medicaid, and 5% had other or unknown insurance or were uninsured; 24% were from the lowest quartile of median zip code income. In the hysterectomy cohort, 57% had private insurance, 16% had Medicare, 19% had Medicaid, and 3% had other or unknown insurance or were uninsured; 27% were from the lowest-income zip codes. Within 30 days of surgery, SSI rates were 2.55% for the colectomy cohort and 0.61% for the hysterectomy cohort. For colectomy, black race (adjusted odds ratio [AOR], 0.71; 95% CI, 0.61-0.82) was associated with lower odds of SSI, whereas Medicare (AOR, 1.25; 95% CI, 1.10-1.41), Medicaid (AOR, 1.23; 95% CI, 1.06-1.44), and low neighborhood income (AOR, 1.14; 95% CI, 1.01-1.29) were associated with higher odds of SSI. For hysterectomy, no social risk factors that were examined in this study had statistically significant associations with SSI after adjustment for clinical risk. Inconsistent associations between social risk factors and SSIs were found. For colectomy, infection prevention programs targeting low-income groups may be important for reducing disparities in this postoperative outcome, and policy makers could consider taking social risk factors into account when evaluating hospital performance.

A cost-effectiveness analysis of mupirocin and chlorhexidine gluconate for Staphylococcus aureus decolonization prior to hip and knee arthroplasty in Alberta, Canada compared to standard of care

BackgroundWhile decolonization of Staphylococcus aureus reduces surgical site infection (SSI) rates following hip and knee arthroplasty, its cost-effectiveness is uncertain. We sought to examine the cost-effectiveness of a decolonization protocol for Staphylococcus aureus prior to hip and knee replacement in Alberta compared to standard care – no decolonization.MethodsDecision analytic models and a probabilistic sensitivity analysis were used for a cost-effectiveness analysis, with the effectiveness of decolonization based on a large published pre- and post- intervention trial. The primary outcomes of the models were infections prevented and health care costs. We modelled the cost-effectiveness of decolonization in a hypothetical cohort of adult patients undergoing hip and knee replacement in Alberta, Canada. Information on the incidence of complex surgical site infections (SSIs), as well as the cost of care for patients with and without SSIs was taken from a provincial infection control database, and health administrative data.ResultsUse of the decolonization bundle was cost saving compared to usual care ($153/person), and resulted in 16 complex Staphylococcus aureus SSIs annually as opposed to 32 (with approximately 8000 hip or knee arthroplasties performed). The probabilistic sensitivity analysis demonstrated that the majority (84%) of the time the decolonization bundle was cost saving. The model was robust to one-way sensitivity analyses conducted within plausible ranges. There were small upfront costs associated with using a decolonization protocol, however, this model demonstrated cost savings over one year. In a Markov model that considered the impact of a decolonization bundle over a lifetime as it pertained to the need for subsequent joint replacements and patient quality of life, the bundle still resulted in cost savings ($161/person).ConclusionsDecolonization for Staphylococcus aureus prior to hip and knee replacements resulted in cost savings and fewer SSIs, and should be considered prior to these procedures.

The cost of managing complex surgical site infections following primary hip and knee arthroplasty: A population-based cohort study in Alberta, Canada.

Nearly 800,000 primary hip and knee arthroplasty procedures are performed annually in North America. Approximately 1% of these are complicated by a complex surgical site infection (SSI), leading to very high healthcare costs. However, population-based studies to properly estimate the economic burden are lacking. We aimed to address this knowledge gap. Economic burden study. Using administrative health and clinical databases, we created a cohort of all patients in Alberta, Canada, who received a primary hip or knee arthroplasty between April 1, 2012, and March 31, 2015. All patients who developed a complex SSI postoperatively were identified through a provincial infection prevention and control database. A combination of corporate microcosting data and gross costing methods were used to determine total mean 12- and 24-month costs, enabling comparison of costs between the infected and noninfected patients. Mean 12-month total costs were significantly greater in patients who developed a complex SSI compared to those who did not (CAD$95,321 [US$68,150] vs CAD$19,893 [US$14,223]; P < .001). The magnitude of the cost difference persisted even after controlling for underlying patient factors. The most commonly identified causative pathogen (38%) was Staphylococcus aureus (95% MSSA). Complex SSIs following hip and knee arthroplasty lead to high healthcare costs, which are expected to rise as the yearly number of surgeries increases. Using our costing estimates, the cost-effectiveness of different strategies to prevent SSIs should be investigated.

The projected burden of complex surgical site infections following hip and knee arthroplasties in adults in the United States, 2020 through 2030.

As the US population ages, the number of hip and knee arthroplasties is expected to increase. Because surgical site infections (SSIs) following these procedures contribute substantial morbidity, mortality, and costs, we projected SSIs expected to occur from 2020 through 2030. We used a stochastic Poisson process to project the number of primary and revision arthroplasties and SSIs. Primary arthroplasty rates were calculated using annual estimates of hip and knee arthroplasty stratified by age and gender from the 2012-2014 Nationwide Inpatient Sample and standardized by census population data. Revision rates, dependent on time from primary procedure, were obtained from published literature and were uniformly applied for all ages and genders. Stratified complex SSI rates for arthroplasties were obtained from 2012-2015 National Healthcare Safety Network data. To evaluate the possible impact of prevention measures, we recalculated the projections with an SSI rate reduced by 30%, the national target established by the US Department of Health and Human Services (HHS). Without a reduction in SSI rates, we projected an increase in complex SSIs following hip and knee arthroplasty of 14% between 2020 and 2030. We projected a total burden of 77,653 SSIs; however, meeting the 30% rate reduction could prevent 23,297 of these SSIs. Given current SSI rates, we project that complex SSI burden for primary and revision arthroplasty may increase due to an aging population. Reducing the SSI rate to the national HHS target could prevent 23,000 SSIs and reduce subsequent morbidity, mortality, and Medicare costs.

Evaluation of the Methods Used by Medicare's Hospital-Acquired Condition Reduction Program to Identify Outlier Hospitals for Surgical Site Infection

The Hospital Acquired Condition Reduction Program (HACRP) is a national pay-for-performance program that includes a measure of surgical site infection (SSI) after hysterectomy and colectomy. This study compares the HACRP SSI measure with other published methods. This was a retrospective cohort study from the Michigan Surgical Quality Collaborative (MSQC). The outcome was 30-day, adjusted deep and organ space SSI ("complex SSI"). Observed-to-expected ratios of complex SSI for each hospital were calculated using HACRP, National Healthcare Safety Network (NHSN), and MSQC methodologies. C-statistics were compared between models. Hospital rankings were compared, and ladder plots show changes in hospitals' HACRP scores that derive from each algorithm. Complex SSI occurred in 1.1% (190 of 16,672) of hysterectomies and 4.8% (n= 514 of 10,725) of colectomies. The HACRP risk-adjustment model for hysterectomy had a C-statistic of 0.55, significantly lower than NHSN (0.61, p= 0.0461) or MSQC models (0.77, p< 0.0001). For colectomy, C-statistics were 0.57, 0.66 (p < 0.0001) and 0.73 (p<0.0001), respectively. For both operations, there were 5 high-outlier hospitals using HACRP, but fewer (4 or 3) using the other methods. Most hospitals in the bottom quartile were not statistical outliers, but would be flagged under HACRP. More than 50% of hospitals changed ranking position between models, which would result in different scores under HACRP. This study showed that the HACRP SSI measure unfairly places hospitals at risk for financial penalties that are not statistical outliers. Policy makers need to weigh the burden of data collection and the accuracy needed to identify hospitals for financial reward orpenalty.

Cesarean Wound Risk Assessment and Management: A Quality Improvement Study [35I

INTRODUCTION: Surgical site infections (SSIs) represent approximately 17% of all hospital-acquired infections with an estimated 500,000 SSIs per year. Cesarean delivery is the primary contributor to SSIs, resulting in patient morbidity and increasing length of hospital stay and medical costs. Studies have shown a benefit to pre-operative antibiotics, but no studies have been done to determine the benefits of stratifying patients into risks categories to tailor management with the goal of preventing infection. METHODS: This is a prospective two-phase quality improvement study in which women undergoing cesarean delivery were categorized according to a risk stratification checklist into high and low-risk groups for developing SSIs. Management for the low risk group consisted of standard pre-operative intravenous antibiotics and a standard pressure dressing. Management for the high risk group consisted of 24 hours of intravenous antibiotics and a specialized Mepilex dressing. SPSS software was used for data analysis. RESULTS: The overall occurrence of SSIs in the low and high risk groups were 7.1% and 3.3% respectively, p-value &lt;0.23. 20% of patients with SSIs had insulin-controlled diabetes, p-value &lt;0.06. Logistic regression demonstrated that both diabetes and BMI were strong predictors of SSIs, p-value &lt;0.01. The incidence of complex SSIs decreased 40% after initiation of the protocol. CONCLUSION: Our data suggest an overall decrease in SSIs after stratifying patients into high and low risk groups with the assigned antibiotics/dressing. Obesity and diabetes are the greatest predictors of SSIs. These risk factors should prompt consideration of use of prolonged antibiotics and a specialized dressing.