Detection of Postoperative Surgical-Site Infections: Comparison of Health Plan–Based Surveillance With Hospital-Based Programs

Patient-Directed Active Surgical Incisions Surveillance May Lead to Further Surgical Site Infection Reduction

Background: Surgical site infections have been a concern for many years, and decades-old articles demonstrate the benefit of surveillance and reporting of these infections with resulting decrease in incidence. Comprehensive surveillance is difficult and often incomplete and is hampered when patients must travel a distance for surgical care. In recent years there has been increasing interest in patient-generated health data (PGHD) that includes patients taking photographs of their surgical incisions. Methods: A selective review of articles on PGHD and photographic images was undertaken in combination with interviews of investigators in this field. Results: There is a possibility that a well-developed system to facilitate patient-provided images of the surgical incision to surgical care providers in a Health Insurance Portability and Accountability Act (HIPAA)-compliant manner could improve surgical surveillance and reduce unnecessary post-operative visits. Conclusions: Further study is required.

An observational study of temperature and thermal images of surgical wounds for detecting delayed wound healing within four days after surgery

AIM

To elucidate the infrared thermal patterns and temperature readings of the surfaces of surgical wounds for detecting delayed wound healing within four days after surgery.

BACKGROUND

The nursing assessment of surgical wounds within the first four days after surgery is commonly based on visual and physical examination. Surgical wounds with delayed healing may be not detected if they do not exhibit signs such as redness or exudate within four days after surgery.

DESIGN

This study was conducted using prospective observational design with reference to the STROBE Statement (see Supporting Information Appendix S1) to examine the temperatures of surgical wounds in their natural settings.

METHODS

Based on convenience sampling, 60 participants admitted to the colorectal surgical ward for enterostoma closure from January-November 2013 were recruited.

RESULTS

Although both infected and noninfected surgical wounds exhibited a significant increase in wound temperature from Days 1-4, the infected wounds revealed a statistically significantly lower temperature than the noninfected ones. Within the infrared thermal images, the infected wounds presented with partial warming of the skin surrounding and along the incision, suggesting that delayed healing could be identified.

CONCLUSION

This study demonstrates that delayed wound healing can be detected within the first four days after surgery for early intervention of prevention and treatment before discharge.

RELEVANCE TO CLINICAL PRACTICE

This paper provides evidence-based information for healthcare professionals in assessing surgical wounds for delayed healing within the first four days after surgery. The findings herein enable the early detection of delayed wound healing, based on which early intervention of prevention and treatment may be instituted for affected patients before their discharge.

Using medication utilization information to develop an asthma severity classification model

Background

Claims data are currently widely used as source data in asthma studies. However, the insufficient information in claims data related to level of asthma severity may negatively impact study findings. The present study develops and validates an asthma severity classification model that uses medication utilization in Taiwan National Health Insurance claims data.

Methods

The National Health Insurance Research Database was used for the years 2006–2012 and included a total of 7221 patients newly diagnosed with asthma in 2007 for model development and in 2008 for model validation. The medication utilization of patients during the first year after the index date was used to classify level of severity, and the acute exacerbation of asthma during the second through fourth years after the index date was used as the outcome variable. Three models were developed, with subjects classified into four, three, and two groups, respectively. The area under the receiver operating characteristic curve (AUC) and the Kaplan-Meier survival curve were used to compare the performances of the classification models.

Results

In development data, the distribution of subjects and acute exacerbation rate among the stage 1 to stage 4 were: 62.71%, 5.54%, 22.79%, and 8.96%, and 8.17%, 9.55%, 11.97%, and 14.91%, respectively. The results also showed the higher severity groups to be more prone to being prescribed oral corticosteroids for asthma control, while lower severity groups were more likely to be prescribed short-acting medication and inhaled corticosteroid treatment. Furthermore, the results of survival analysis showed two-group classification was recommended and yield moderate performance (AUC = 0.671). In validation data, the distribution of subjects, acute exacerbation rates, and medication uses among stages were similar to those in development data, and the results of survival analysis were also the same.

Conclusions

Understanding asthma severity is critical to conducting effective, scholarly research on asthma, which currently uses claims data as a primary data source. The model developed in the present study not only overcomes a gap in the current literature but also provides an opportunity to improve the validity and quality of claims-data-based asthma studies.

Surgical site infections after lung resection: a prospective study of risk factors in 1,091 consecutive patients

Background

To assess incidence and risk factors of surgical site infections (SSI) (wound infection, pneumonia, empyema) in a monocentric series of patients undergoing lung resection over a decade.

Methods

All patients undergoing lung resection at our institution in 2006-2015 [wedge resection, n=579; lobectomy, n=472 (12% after chemo/radiotherapy); pneumonectomy, n=40 (47% after chemo/radiotherapy)], were prospectively enrolled. Perioperative SSI risk factors were recorded: age, gender, blood haemoglobin, lymphocyte count, serum albumin, forced expiratory volume in 1 second percentage (FEV1%) of predicted, antibiotic prophylaxis, length of stay, diabetes, malignancy, steroid therapy, induction chemo/radiotherapy, resection in 2006-2010/2011-2015, urgent/elective procedure, videothoracoscopic/open approach, resection type, operative time. SSIs diagnosed within 30 days from surgery were prospectively recorded and association with risk factors was evaluated.

Results

Of the 1,091 resected patients [median age, 65 (range, 13-91) years; male, 74%; malignancy, 65%], 124 (11.4%) developed one or more SSI. Wound infection, pneumonia and empyema rates were respectively 3.2%, 8.3% and 1.9%, stable through the decade. Overall infection rates after wedge resection, lobectomy and pneumonectomy were 4.8%, 17.4% and 35.0%, respectively. Thirty-day postoperative mortality was 0.6%; of the 7 deaths, 4 were causally related with SSI. Multivariable analysis showed that male gender, diabetes, preoperative steroids, induction chemo/radiotherapy, missed antibiotic prophylaxis and resection type were independent risk factors for overall SSI.

Conclusions

SSI rates after lung resection were stable over the decade. The observed 11.4% frequency of SSI indicates that postoperative infections remain a relevant issue and a predominant cause of mortality after lung surgery. Focusing on SSI risk factors that are perioperatively modifiable may improve surgical results.

Validation of ICD-9-CM Diagnosis Codes for Surgical Site Infection and Noninfectious Wound Complications After Mastectomy

BACKGROUND Few studies have validated ICD-9-CM diagnosis codes for surgical site infection (SSI), and none have validated coding for noninfectious wound complications after mastectomy. OBJECTIVES To determine the accuracy of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis codes in health insurer claims data to identify SSI and noninfectious wound complications, including hematoma, seroma, fat and tissue necrosis, and dehiscence, after mastectomy. METHODS We reviewed medical records for 275 randomly selected women who were coded in the claims data for mastectomy with or without immediate breast reconstruction and had an ICD-9-CM diagnosis code for a wound complication within 180 days after surgery. We calculated the positive predictive value (PPV) to evaluate the accuracy of diagnosis codes in identifying specific wound complications and the PPV to determine the accuracy of coding for the breast surgical procedure. RESULTS The PPV for SSI was 57.5%, or 68.9% if cellulitis-alone was considered an SSI, while the PPV for cellulitis was 82.2%. The PPVs of individual noninfectious wound complications ranged from 47.8% for fat necrosis to 94.9% for seroma and 96.6% for hematoma. The PPVs for mastectomy, implant, and autologous flap reconstruction were uniformly high (97.5%-99.2%). CONCLUSIONS Our results suggest that claims data can be used to compare rates of infectious and noninfectious wound complications after mastectomy across facilities, even though PPVs vary by specific type of postoperative complication. The accuracy of coding was highest for cellulitis, hematoma, and seroma, and a composite group of noninfectious complications (fat necrosis, tissue necrosis, or dehiscence). Infect Control Hosp Epidemiol 2017;38:334-339.

Public Disclosure of Healthcare-Associated Infections: The Role of the Society for Healthcare Epidemiology of America

Prior to 2004, only two states, Pennsylvania and Illinois, had enacted legislation requiring healthcare facilities to collect nosocomial or healthcare-associated infection (HAI) data intended for public disclosure. In 2004, two additional states, Missouri and Florida, passed disclosure laws. Currently, several other states are considering similar legislation. In California, Senate Bill 1487 requiring hospitals to collect HAI data and report them to the Office of Statewide Health Planning was passed by the legislature, but was not signed into law by Governor Schwarzenegger, effectively vetoing it. The impetus for these laws is complex. Support comes from consumer advocates, who argue that the public has the right to be informed, and from others who view HAI as preventable and hope that public disclosure would provide an incentive to healthcare providers and institutions to improve their care.

Administrative Data Fail to Accurately Identify Cases of Healthcare-Associated Infection

Objective.

Some policy makers have embraced public reporting of healthcare-associated infections (HAIs) as a strategy for improving patient safety and reducing healthcare costs. We compared the accuracy of 2 methods of identifying cases of HAI: review of administrative data and targeted active surveillance.

Design, Setting, and Participants.

A cross-sectional prospective study was performed during a 9-month period in 2004 at the Children's Hospital of Philadelphia, a 418-bed academic pediatric hospital. “True HAI” cases were defined as those that met the definitions of the National Nosocomial Infections Surveillance System and that were detected by a trained infection control professional on review of the medical record. We examined the sensitivity and the positive and negative predictive values of identifying HAI cases by review of administrative data and by targeted active surveillance.

Results.

We found similar sensitivities for identification of HAI cases by review of administrative data (61%) and by targeted active surveillance (76%). However, the positive predictive value of identifying HAI cases by review of administrative data was poor (20%), whereas that of targeted active surveillance was 100%.

Conclusions.

The positive predictive value of identifying HAI cases by targeted active surveillance is very high. Additional investigation is needed to define the optimal detection method for institutions that provide HAI data for comparative analysis.

Postdischarge surveillance for infection following cesarean section: A prospective cohort study comparing methodologies

OBJECTIVE

To assess how enhanced postdischarge telephone follow-up calls would improve case finding for surgical site infection (SSI) surveillance after cesarean section.

METHODS

We conducted a prospective cohort study of all patients who delivered by cesarean section between April 22 and August 22, 2010. In addition to our routine surveillance, using clinical databases and electronic patient records, we also made follow-up calls to the patients at 7, 14, and 30 days postoperation. A standard questionnaire with questions about symptoms of SSI, health-seeking behaviors, and treatment received was administered. Descriptive statistics and univariate analysis were performed to assess the effect of the enhanced surveillance.

RESULTS

One hundred ninety-three patients underwent cesarean section during this study period. Standard surveillance identified 14 infections with telephone follow-ups identifying an additional 5 infections. Using the call as a gold standard, the sensitivity of the standard methodology to capture SSI was 73.3%. The duration of the calls ranged from 1 to 5 minutes and were well received by the patients.

CONCLUSIONS

Results suggest that follow-up telephone calls to patients following cesarean section identifies 26.3% of the total SSIs. Enhanced surveillance can provide more informed data to enhance performance and avoid underestimation of rates.

Accuracy of administrative data for surveillance of healthcare-associated infections: a systematic review

OBJECTIVE

Measuring the incidence of healthcare-associated infections (HAI) is of increasing importance in current healthcare delivery systems. Administrative data algorithms, including (combinations of) diagnosis codes, are commonly used to determine the occurrence of HAI, either to support within-hospital surveillance programmes or as free-standing quality indicators. We conducted a systematic review evaluating the diagnostic accuracy of administrative data for the detection of HAI.

METHODS

Systematic search of Medline, Embase, CINAHL and Cochrane for relevant studies (1995-2013). Methodological quality assessment was performed using QUADAS-2 criteria; diagnostic accuracy estimates were stratified by HAI type and key study characteristics.

RESULTS

57 studies were included, the majority aiming to detect surgical site or bloodstream infections. Study designs were very diverse regarding the specification of their administrative data algorithm (code selections, follow-up) and definitions of HAI presence. One-third of studies had important methodological limitations including differential or incomplete HAI ascertainment or lack of blinding of assessors. Observed sensitivity and positive predictive values of administrative data algorithms for HAI detection were very heterogeneous and generally modest at best, both for within-hospital algorithms and for formal quality indicators; accuracy was particularly poor for the identification of device-associated HAI such as central line associated bloodstream infections. The large heterogeneity in study designs across the included studies precluded formal calculation of summary diagnostic accuracy estimates in most instances.

CONCLUSIONS

Administrative data had limited and highly variable accuracy for the detection of HAI, and their judicious use for internal surveillance efforts and external quality assessment is recommended. If hospitals and policymakers choose to rely on administrative data for HAI surveillance, continued improvements to existing algorithms and their robust validation are imperative.

Does Categorization Method Matter in Exploring Volume-Outcome Relation? A Multiple Categorization Methods Comparison in Coronary Artery Bypass Graft Surgery Surgical Site Infection

BACKGROUND

Volume-infection relation studies have been published for high-risk surgical procedures, although the conclusions remain controversial. Inconsistent results may be caused by inconsistent categorization methods, the definitions of service volume, and different statistical approaches. The purpose of this study was to examine whether a relation exists between provider volume and coronary artery bypass graft (CABG) surgical site infection (SSI) using different categorization methods.

METHODS

A population-based cross-sectional multi-level study was conducted. A total of 10,405 patients who received CABG surgery between 2006 and 2008 in Taiwan were recruited. The outcome of interest was surgical site infection for CABG surgery. The associations among several patient, surgeon, and hospital characteristics was examined. The definition of surgeons' and hospitals' service volume was the cumulative CABG service volumes in the previous year for each CABG operation and categorized by three types of approaches: Continuous, quartile, and k-means clustering.

RESULTS

The results of multi-level mixed effects modeling showed that hospital volume had no association with SSI. Although the relation between surgeon volume and surgical site infection was negative, it was inconsistent among the different categorization methods.

CONCLUSIONS

Categorization of service volume is an important issue in volume-infection study. The findings of the current study suggest that different categorization methods might influence the relation between volume and SSI. The selection of an optimal cutoff point should be taken into account for future research.

Which Kind of Provider's Operation Volumes Matters? Associations between CABG Surgical Site Infection Risk and Hospital and Surgeon Operation Volumes among Medical Centers in Taiwan

BACKGROUND

Volume-infection relationships have been examined for high-risk surgical procedures, but the conclusions remain controversial. The inconsistency might be due to inaccurate identification of cases of infection and different methods of categorizing service volumes. This study takes coronary artery bypass graft (CABG) surgical site infections (SSIs) as an example to examine whether a relationship exists between operation volumes and SSIs, when different SSIs case identification, definitions and categorization methods of operation volumes were implemented.

METHODS

A population-based cross-sectional multilevel study was conducted. A total of 7,007 patients who received CABG surgery between 2006 and 2008 from 19 medical centers in Taiwan were recruited. SSIs associated with CABG surgery were identified using International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9 CM) codes and a Classification and Regression Trees (CART) model. Two definitions of surgeon and hospital operation volumes were used: (1) the cumulative CABG operation volumes within the study period; and (2) the cumulative CABG operation volumes in the previous one year before each CABG surgery. Operation volumes were further treated in three different ways: (1) a continuous variable; (2) a categorical variable based on the quartile; and (3) a data-driven categorical variable based on k-means clustering algorithm. Furthermore, subgroup analysis for comorbidities was also conducted.

RESULTS

This study showed that hospital volumes were not significantly associated with SSIs, no matter which definitions or categorization methods of operation volume, or SSIs case identification approaches were used. On the contrary, the relationships between surgeon's volumes varied. Most of the models demonstrated that the low-volume surgeons had higher risk than high-volume surgeons.

CONCLUSION

Surgeon volumes were more important than hospital volumes in exploring the relationship between CABG operation volumes and SSIs in Taiwan. However, the relationships were not robust. Definitions and categorization methods of operation volume and correct identification of SSIs are important issues for future research.

Postdischarge Surgical Site Infection Surveillance Practices in Washington Acute Care Hospitals

Little is known about postdischarge surveillance practices currently in place among American hospitals. This survey describes practices used by acute care hospitals covered by Washington State's legislated mandate for public reporting of surgical site infections. While the vast majority of facilities use multiple techniques, wide variation in practices was discovered.

Infect Control Hosp Epidemiol 2012;33(1):8

Validation of a Modified Version of the National Nosocomial Infections Surveillance System Risk Index for Health Services Research

Objective.

To validate the National Nosocomial Infections Surveillance system risk index through administrative data to predict surgical site infections.

Design.

Retrospective cohort study.

Setting.

Population-based analysis in Ontario, Canada.

Patients.

All elderly patients who underwent elective surgery from April 1, 1992, through March 31, 2006 (n = 469,349).

Methods.

Data on procedural and patient outcomes were gathered from linked population-wide hospital discharge records and physician claims. The 75th percentile of surgical duration was estimated through anesthesiologist billing fees recorded in 15-minute increments; the American Society of Anesthesiology score of at least 3 out of 5 was estimated by diagnostic codes for severe systemic illness; and all surgeries were classified as clean or clean-contaminated because of their elective nature (thus, the maximum score on the modified index was 2).

Results.

A total of 147,216 surgeries (31%) had a score of 0;246,592 (53%) had a score of 1; and 75,541 (16%) had a score of 2 on the modified index. The 30-day risk of surgical site infection increased with each increment in the modified index (score of 0, 5.4%; score of 1, 8.0%; score of 2, 14.3%; P < .001). The association was evident for surgical site infection diagnosed during the index admission (score of 0, 2.0%; score of 1, 3.7%; score of 2, 8.9%; P < .001), as well as that associated with reoperation or death (score of 0, 0.04%; score of 1, 0.23%; score of 2, 0.73%; P < .001). The modified index predicted increases in surgical site infection risk within each of 11 surgical subgroups. In accord with past research, the modified index had modest discrimination (C statistic, 0.59), and the majority of surgical site infections (72%) occurred within lower risk strata.

Conclusions.

The modified index predicts surgical site infection in population-based analyses and is associated with incremental increases in risk.

Is it possible to identify cases of coronary artery bypass graft postoperative surgical site infection accurately from claims data?

Background

Claims data has usually been used in recent studies to identify cases of healthcare-associated infection. However, several studies have indicated that the ICD-9-CM codes might be inappropriate for identifying such cases from claims data; therefore, several researchers developed alternative identification models to correctly identify more cases from claims data. The purpose of this study was to investigate three common approaches to develop alternative models for the identification of cases of coronary artery bypass graft (CABG) surgical site infection, and to compare the performance between these models and the ICD-9-CM model.

Methods

The 2005–2008 National Health Insurance claims data and healthcare-associated infection surveillance data from two medical centers were used in this study for model development and model verification. In addition to the use of ICD-9-CM codes, this study also used classification algorithms, a multivariable regression model, and a decision tree model in the development of alternative identification models. In the classification algorithms, we defined three levels (strict, moderate, and loose) of the criteria in terms of their strictness. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were used to evaluate the performance of each model.

Results

The ICD-9-CM-based model showed good specificity and negative predictive value, but sensitivity and positive predictive value were poor. Performances of the other models were varied, except for negative predictive value. Among the models, the performance of the decision tree model was excellent, especially in terms of positive predictive value.

Conclusion

The accuracy of identification of cases of CABG surgical site infection is an important issue in claims data. Use of the decision tree model to identify such cases can improve the accuracy of patient-level outcome research. This model should be considered when performing future research using claims data.

The utility of claims data for infection surveillance following anterior cruciate ligament reconstruction

OBJECTIVE

To explore the feasibility of identifying anterior cruciate ligament (ACL) allograft implantations and infections using claims.

DESIGN

Retrospective cohort study.

METHODS

We identified ACL reconstructions using procedure codes at 6 health plans from 2000 to 2008. We then identified potential infections using claims-based indicators of infection, including diagnoses, procedures, antibiotic dispensings, specialty consultations, emergency department visits, and hospitalizations. Patients' medical records were reviewed to determine graft type, validate infection status, and calculate sensitivity and positive predictive value (PPV) for indicators of ACL allografts and infections.

RESULTS

A total of 11,778 patients with codes for ACL reconstruction were identified. After chart review, PPV for ACL reconstruction was 96% (95% confidence interval [CI], 94%-97%). Of the confirmed ACL reconstructions, 39% (95% CI, 35%-42%) used allograft tissues. The deep infection rate after ACL reconstruction was 1.0% (95% CI, 0.7%-1.4%). The odds ratio of infection for allografts versus autografts was 0.41 (95% CI, 0.19-0.78). Sensitivity of individual claims-based indicators for deep infection after ACL reconstruction ranged from 0% to 75% and PPV from 0% to 100%. Claims-based infection indicators could be combined to enhance sensitivity or PPV but not both.

CONCLUSIONS

While claims data accurately identify ACL reconstructions, they poorly distinguish between allografts and autografts and identify infections with variable accuracy. Claims data could be useful to monitor infection trends after ACL reconstruction, with different algorithms optimized for different surveillance goals.

Impact of Medicare's payment policy on mediastinitis following coronary artery bypass graft surgery in US hospitals

BACKGROUND

The Centers for Medicare and Medicaid Services (CMS) implemented a policy in October 2008 to eliminate additional Medicare payment for mediastinitis following coronary artery bypass graft (CABG) surgery.

OBJECTIVE

To evaluate the impact of this policy on mediastinitis rates, using Medicare claims and National Healthcare Safety Network (NHSN) prospective surveillance data.

METHODS

We used an interrupted time series design to compare mediastinitis rates before and after the policy, adjusted for secular trends. Billing rates came from Medicare inpatient claims following 638,761 CABG procedures in 1,234 US hospitals (January 2006-September 2010). Prospective surveillance rates came from 151 NHSN hospitals in 29 states performing 94,739 CABG procedures (January 2007-September 2010). Logistic regression mixed-effects models estimated trends for mediastinitis rates.

RESULTS

We found a sudden drop in coding for index admission mediastinitis at the time of policy implementation (odds ratio, 0.36 [95% confidence interval (CI), 0.23-0.57]) and a decreasing trend in coding for index admission mediastinitis in the postintervention period compared with the preintervention period (ratio of slopes, 0.83 [95% CI, 0.74-0.95]). However, we saw no impact of the policy on infection rates as measured using NHSN data. Our results were not affected by changes in patient risk over time, heterogeneity in hospital demographics, or timing of hospital participation in NHSN.

CONCLUSIONS

The CMS policy of withholding additional Medicare payment for mediastinitis on the basis of claims-based evidence of infection was associated with changes in coding for infections but not with changes in actual infection rates during the first 2 years after policy implementation.

Risk Factors for Postoperative Chest Wound Infections Due to Gram-negative Bacteria in Cardiac Surgery Patients

Gram-negative bacteria account for up to 35% of postoperative sternal wound infections (SWI) in patients undergoing cardiac surgery. Despite this, risk factors for Gram-negative SWI have not been investigated. The objective of this study was to define risk factors associated with Gram-negative SWI in patients undergoing cardiac surgery. 2590 patients undergoing cardiac surgery between 2002-2005 were prospectively monitored for development of SWI. Patient, operative, and post-operative risk factors were compared among patients that developed Gram-negative SWI and Gram-positive SWI to uninfected controls using univariate and multivariate analysis. A p < 0.05 was considered significant. Surgical site infections developed in 152 (5.9%) patients. Isolates were recovered from the sternum for 128 (5.0%) patients, from the leg donor site for 19 (0.73%) patients, and from the sternum and donor site for 5 (0.19%) patients. Gram-positive pathogens were isolated from 83 (3.3%) patients, Gram-negative pathogens from 42 (1.6%) patients, and mixed pathogens from 27 (1.0%) patients. Hospital admission greater than 48 hours before surgery (OR: 2.25; 95% CI: 1.11 - 4.58), ventilator-dependency preoperatively (OR: 5.32 95% CI: 2.22 - 12.75), and thoracentesis procedure postoperatively (OR: 3.71; 95% CI: 1.45 - 9.49) and diabetes (OR: 2.04; 95% CI: 1.17 - 3.55) were identified as significant risk factors for SWI due to Gram-negative bacteria using multivariate logistic regression. Diabetes, increased age, and peripheral vascular disease were identified as significant risk factors for SWI due to Gram-positive bacteria (p < 0.05, each). The risk factors associated with Gram-negative SWI differed significantly from those associated with Gram-positive SWI. Risk factors associated with Gram-negative SWI were identified. Unique interventions may be necessary to prevent Gram-negative SWI in cardiac surgery patients.

Surgical site infection: the principles and practice of surveillance. Part 1: Key concepts in the methodology of SSI surveillance

urgical site infections (SSI) account for a major proportion of healthcare associated infections (HCAI) yet many hospitals capture little data on the risk of SSI in patients undergoing surgery and therefore have little assurance about the quality of infection prevention in their operating departments. This paper is the first part of a two part series that will examine the principles and practice of surveillance of SSI. Part 2 will examine the analysis of SSI data and the use of the results to change practice. This paper reviews the principles that underpin SSI surveillance methodology, key concepts that affect the accuracy of data capture systems and strategies for addressing them, including risk factors and active case finding systems to ensure detection of SSI, including those that develop after discharge from hospital.

Use of Medicare claims to identify US hospitals with a high rate of surgical site infection after hip arthroplasty

OBJECTIVE

To assess the ability of Medicare claims to identify US hospitals with high rates of surgical site infection (SSI) after hip arthroplasty.

DESIGN

Retrospective cohort study.

SETTING

Acute care US hospitals.

PARTICIPANTS

Fee-for-service Medicare patients 65 years of age and older who underwent hip arthroplasty in US hospitals from 2005 through 2007.

METHODS

Hospital rankings were derived from claims codes suggestive of SSI, adjusted for age, sex, and comorbidities, while using generalized linear mixed models to account for hospital volume. Medical records were obtained for validation of infection on a random sample of patients from hospitals ranked in the best and worst deciles of performance. We then calculated the risk-adjusted odds of developing a chart-confirmed SSI after hip arthroplasty in hospitals ranked by claims into worst- versus best-performing deciles.

RESULTS

Among 524,892 eligible Medicare patients who underwent hip arthroplasty at 3,296 US hospitals, a patient who underwent surgery in a hospital ranked in the worst-performing decile based on claims-based evidence of SSI had 2.9-fold higher odds of developing a chart-confirmed SSI relative to a patient with the same age, sex, and comorbidities in a hospital ranked in the best-performing decile (95% confidence interval, 2.2-3.7).

CONCLUSIONS

Medicare claims successfully distinguished between hospitals with high and low SSI rates following hip arthroplasty. These claims can identify potential outlier hospitals that merit further evaluation. This strategy can also be used to validate the completeness of public reporting of SSI.

Enhanced surgical site infection surveillance following hysterectomy, vascular, and colorectal surgery

OBJECTIVE

To evaluate the use of inpatient pharmacy and administrative data to detect surgical site infections (SSIs) following hysterectomy and colorectal and vascular surgery.

DESIGN

Retrospective cohort study.

SETTING

Five hospitals affiliated with academic medical centers.

PATIENTS

Adults who underwent abdominal or vaginal hysterectomy, colorectal surgery, or vascular surgery procedures between July 1, 2003, and June 30, 2005.

METHODS

We reviewed the medical records of weighted, random samples drawn from 3,079 abdominal and vaginal hysterectomy, 4,748 colorectal surgery, and 3,332 vascular surgery procedures. We compared routine surveillance with screening of inpatient pharmacy data and diagnosis codes and then performed medical record review to confirm SSI status.

RESULTS

Medical records from 823 hysterectomy, 736 colorectal surgery, and 680 vascular surgery procedures were reviewed. SSI rates determined by antimicrobial- and/or diagnosis code-based screening followed by medical record review (enhanced surveillance) were substantially higher than rates determined by routine surveillance (4.3% [95% confidence interval, 3.6%-5.1%] vs 2.7% for hysterectomies, 7.1% [95% confidence interval, 6.7%-8.2%] vs 2.0% for colorectal procedures, and 2.3% [95% confidence interval, 1.9%-2.9%] vs 1.4% for vascular procedures). Enhanced surveillance had substantially higher sensitivity than did routine surveillance to detect SSI (92% vs 59% for hysterectomies, 88% vs 22% for colorectal procedures, and 72% vs 43% for vascular procedures). A review of medical records confirmed SSI for 31% of hysterectomies, 20% of colorectal procedures, and 31% of vascular procedures that met the enhanced screening criteria.

CONCLUSION

Antimicrobial- and diagnosis code-based screening may be a useful method for enhancing and streamlining SSI surveillance for a variety of surgical procedures, including those procedures targeted by the Centers for Medicare and Medicaid Services.

Hospital-acquired infections

Health-acquired infection (HAI) is defined as a localized or systemic condition resulting from an adverse reaction to the presence of infectious agents or its toxins. This article focuses on HAIs that are well studied, common, and costly (direct, indirect, and intangible). The HAIs reviewed are catheter-related bloodstream infection, ventilator-associated pneumonia, surgical site infection, and catheter-associated urinary tract infection. This article excludes discussion of Clostridium difficile infections and vancomycin-resistant Enterococcus.

Use of Medicare diagnosis and procedure codes to improve detection of surgical site infections following hip arthroplasty, knee arthroplasty, and vascular surgery

OBJECTIVE

To evaluate the use of routinely collected electronic health data in Medicare claims to identify surgical site infections (SSIs) following hip arthroplasty, knee arthroplasty, and vascular surgery.

DESIGN

Retrospective cohort study.

SETTING

Four academic hospitals that perform prospective SSI surveillance.

METHODS

We developed lists of International Classification of Diseases, Ninth Revision, and Current Procedural Terminology diagnosis and procedure codes to identify potential SSIs. We then screened for these codes in Medicare claims submitted by each hospital on patients older than 65 years of age who had undergone 1 of the study procedures during 2007. Each site reviewed medical records of patients identified by either claims codes or traditional infection control surveillance to confirm SSI using Centers for Disease Control and Prevention/National Healthcare Safety Network criteria. We assessed the performance of both methods against all chart-confirmed SSIs identified by either method.

RESULTS

Claims-based surveillance detected 1.8-4.7-fold more SSIs than traditional surveillance, including detection of all previously identified cases. For hip and vascular surgery, there was a 5-fold and 1.6-fold increase in detection of deep and organ/space infections, respectively, with no increased detection of deep and organ/space infections following knee surgery. Use of claims to trigger chart review led to confirmation of SSI in 1 out of 3 charts for hip arthroplasty, 1 out of 5 charts for knee arthroplasty, and 1 out of 2 charts for vascular surgery.

CONCLUSION

Claims-based SSI surveillance markedly increased the number of SSIs detected following hip arthroplasty, knee arthroplasty, and vascular surgery. It deserves consideration as a more effective approach to target chart reviews for identifying SSIs.

National surveillance of surgical-site infection through register-based analysis of antibiotic use after inguinal hernia repair

BACKGROUND

Systematic surveillance of surgical-site infections is not standard. The aim of this retrospective cohort study was to evaluate the feasibility of using existing national health registers for surveillance of postoperative antibiotic treatment suggestive of surgical-site infection.

METHODS

Data from national registers on hospital admissions and drug use were combined. Antibiotic purchases by 8856 patients subject to ambulatory care for inguinal hernia repair in Sweden during 2006 were ascertained during a 30-day interval immediately after surgery (postsurgical period) and in an 11-month control period (6 months before and 5 months after the postsurgical period).

RESULTS

The incidence of first purchases of skin and soft tissue antibiotics was 245 per 8697 person-months in the first postoperative month and 180 per 52 612 person-months in the preoperative control period, representing a 1-month risk difference of 2.4 (95 per cent confidence interval (c.i.) 2.0 to 2.7) per cent. Hence, a 1-month risk of 2.4 per cent could be attributed tentatively to the surgery. The rate of episodes with antibiotics used mainly for skin and soft tissue infection was sevenfold higher in the first postoperative month than in the control period (rate ratio 7.01, 95 per cent c.i. 5.94 to 8.27).

CONCLUSION

The risk of antibiotic treatment during the postsurgical period was of the same order of magnitude as infection rates reported in the Swedish Hernia Register and review studies. Surveillance of postoperative antibiotic use may be considered as a resource-saving surrogate marker for surgical-site infections or an indicator of inappropriate use.

Discharge after discharge: predicting surgical site infections after patients leave hospital

In this population-based retrospective cohort study, we examined the frequency, severity, and prediction of post-discharge surgical site infections (SSIs). We evaluated all patients admitted for their first elective surgical procedure in Ontario, Canada, between 1 April 2002 and 31 March 2008. Procedure and patient characteristics were derived from linked hospital, emergency room and physician claims databases within Canada's universal healthcare system. The 30 day risk of SSI was derived from the initial hospital admission, outpatient consultations, return emergency room visits and readmissions. The cohort included 622 683 patients, of whom 84 081 (13.5%) were diagnosed with SSI, and more than half (48 725) were diagnosed post-discharge. Post-discharge infections were associated with an increased risk of reoperation (odds ratio: 2.28; 95% confidence interval: 2.11-2.48), return emergency room visit (9.08; 8.89-9.27), and readmission (6.16; 5.98-6.35). The most common risk index predicted incremental increases in the risk of in-hospital SSI, but did not predict increases in the risk of post-discharge infection. Patients with post-discharge infections had baseline characteristics more akin to uninfected patients than patients with in-hospital infections. Predictors of post-discharge infection included shorter procedure duration, shorter length of stay, rural residence, alcoholism, diabetes and obesity. Post-discharge SSIs are frequent, severe, scattered over time and location, and hard to predict using common risk indices. They represent an important hidden burden in our healthcare system.

Administrative coding data, compared with CDC/NHSN criteria, are poor indicators of health care-associated infections

BACKGROUND

ICD-9-CM coding alone has been proposed as a method of surveillance for health care-associated infections (HAIs). The accuracy of this method, however, relative to accepted infection control criteria is not known.

METHODS

Retrospective analysis of patients at an academic medical center in 2005 who underwent surgical procedures or who were at risk for catheter-associated bloodstream infections or ventilator-associated pneumonia was performed. Patients previously identified with HAIs by Centers for Disease Control and Prevention's National Healthcare Safety Network surveillance methods were compared with those of the same risk group identified by secondary infection ICD-9-CM codes. Discordant cases identified by only coding were all rereviewed and adjusted prior to final analysis. When coding and surveillance were both negative, a sample of patients was used to estimate the proportion of false negatives in this group.

RESULTS

The positive predictive values (PPVs) ranged from 0.14 to 0.51 with an aggregate of 0.23, even after adjustment for additional cases detected on subsequent medical record review. The negative predictive values (NPVs) ranged from 0.91 to 1.00, with an aggregate of 0.96. The estimates of the true variance of PPVs and NPVs across surgical procedures were small (0.0129, standard error, 0.009; 0.000145, standard error, 0.00019, respectively) and could be mostly explained by variation in prevalence of surgical site infections.

CONCLUSION

Administrative coding alone appears to be a poor tool to be used as an infection control surveillance method. Its proposed use for routine HAI surveillance, public reporting of HAIs, interfacility comparisons, and nonpayment for performance should be seriously questioned.

Post-discharge surgical site surveillance: does patient education improve reliability of diagnosis?

Post-discharge surgical infection surveillance by patients remains an integral part of many infection control programmes despite proven unreliability. We attempted to improve the validity of patient recognition of signs and symptoms of wound infection and post-discharge postal questionnaire responses through specific education prior to discharge. In total, 588 patients were studied after random assignment into two intervention groups, one of which received relevant education. Both groups were followed for four weeks post-operatively, with features of infection assessed weekly by experienced infection control nurses (ICNs) and by patient responses to routine postal questionnaires. Those patients who received education demonstrated a significantly poorer correlation with ICN diagnosis compared to the non-educated group (Kappa 0.69 and 0.81 respectively, P=0.05). Both patient groups achieved the same sensitivity for recall (83.3%), with high specificity demonstrated by both groups [educated (93.7%); non-educated (98.1%)]. The positive predictive value was 65.2% for the educated group and 83.3% for the non-educated patient group. When infected wounds identified by patients were examined for the proportion that were overdiagnosed, the excess of SSI identified by the educated patient group was 44.4% and by the non-educated group 16.7%. These results suggest that pre-discharge education causes patients to overdiagnose clinical features of wound infection and fails to improve the validity of diagnosis. This outcome further questions the value of post-discharge infection rates obtained by patient self-assessment as a measure of quality of performance.

Developing algorithms for healthcare insurers to systematically monitor surgical site infection rates

BACKGROUND

Claims data provide rapid indicators of SSIs for coronary artery bypass surgery and have been shown to successfully rank hospitals by SSI rates. We now operationalize this method for use by payers without transfer of protected health information, or any insurer data, to external analytic centers.

RESULTS

We performed a descriptive study testing the operationalization of software for payers to routinely assess surgical infection rates among hospitals where enrollees receive cardiac procedures. We developed five SAS programs and a user manual for direct use by health plans and payers. The manual and programs were refined following provision to two national insurers who applied the programs to claims databases, following instructions on data preparation, data validation, analysis, and verification and interpretation of program output. A final set of programs and user manual successfully guided health plan programmer analysts to apply SSI algorithms to claims databases. Validation steps identified common problems such as incomplete preparation of data, missing data, insufficient sample size, and other issues that might result in program failure. Several user prompts enabled health plans to select time windows, strata such as insurance type, and the threshold number of procedures performed by a hospital before inclusion in regression models assessing relative SSI rates among hospitals. No health plan data was transferred to outside entities. Programs, on default settings, provided descriptive tables of SSI indicators stratified by hospital, insurer type, SSI indicator (inpatient, outpatient, antibiotic), and six-month period. Regression models provided rankings of hospital SSI indicator rates by quartiles, adjusted for comorbidities. Programs are publicly available without charge.

CONCLUSION

We describe a free, user-friendly software package that enables payers to routinely assess and identify hospitals with potentially high SSI rates complicating cardiac procedures.

Methods for identifying surgical wound infection after discharge from hospital: a systematic review

Background

Wound infections are a common complication of surgery that add significantly to the morbidity of patients and costs of treatment. The global trend towards reducing length of hospital stay post-surgery and the increase in day case surgery means that surgical site infections (SSI) will increasingly occur after hospital discharge. Surveillance of SSIs is important because rates of SSI are viewed as a measure of hospital performance, however accurate detection of SSIs post-hospital discharge is not straightforward.

Methods

We conducted a systematic review of methods of post discharge surveillance for surgical wound infection and undertook a national audit of methods of post-discharge surveillance for surgical site infection currently used within United Kingdom NHS Trusts.

Results

Seven reports of six comparative studies which examined the validity of post-discharge surveillance methods were located; these involved different comparisons and some had methodological limitations, making it difficult to identify an optimal method. Several studies evaluated automated screening of electronic records and found this to be a useful strategy for the identification of SSIs that occurred post discharge. The audit identified a wide range of relevant post-discharge surveillance programmes in England, Scotland and Wales and Northern Ireland; however, these programmes used varying approaches for which there is little supporting evidence of validity and/or reliability.

Conclusion

In order to establish robust methods of surveillance for those surgical site infections that occur post discharge, there is a need to develop a method of case ascertainment that is valid and reliable post discharge. Existing research has not identified a valid and reliable method. A standardised definition of wound infection (e.g. that of the Centres for Disease Control) should be used as a basis for developing a feasible, valid and reliable approach to defining post discharge SSI. At a local level, the method used to ascertain post discharge SSI will depend upon the purpose of the surveillance, the nature of available routine data and the resources available.

Comparing bloodstream infection rates: the effect of indicator specifications in the evaluation of processes and indicators in infection control (EPIC) study

OBJECTIVE

Bloodstream infection (BSI) rates are used as comparative clinical performance indicators; however, variations in definitions and data-collection approaches make it difficult to compare and interpret rates. To determine the extent to which variation in indicator specifications affected infection rates and hospital performance rankings, we compared absolute rates and relative rankings of hospitals across 5 BSI indicators.

DESIGN

Multicenter observational study. BSI rate specifications varied by data source (clinical data, administrative data, or both), scope (hospital wide or intensive care unit specific), and inclusion/exclusion criteria. As appropriate, hospital-specific infection rates and rankings were calculated by processing data from each site according to 2-5 different specifications.

SETTING

A total of 28 hospitals participating in the EPIC study.

PARTICIPANTS

Hospitals submitted deidentified information about all patients with BSIs from January through September 1999.

RESULTS

Median BSI rates for 2 indicators based on intensive care unit surveillance data ranged from 2.23 to 2.91 BSIs per 1000 central-line days. In contrast, median rates for indicators based on administrative data varied from 0.046 to 7.03 BSIs per 100 patients. Hospital-specific rates and rankings varied substantially as different specifications were applied; the rates of 8 of 10 hospitals were both greater than and less than the mean. Correlations of hospital rankings among indicator pairs were generally low (rs=0-0.45), except when both indicators were based on intensive care unit surveillance (rs = 0.83).

CONCLUSIONS

Although BSI rates seem to be a logical indicator of clinical performance, the use of various indicator specifications can produce remarkably different judgments of absolute and relative performance for a given hospital. Recent national initiatives continue to mix methods for specifying BSI rates; this practice is likely to limit the usefulness of such information for comparing and improving performance.

Evaluation of postdischarge surveillance of surgical site infections after total hip and knee arthroplasty

BACKGROUND

Artificial joint replacement of hip (HPRO) and knee (KPRO) are 2 of about 20 categories of operative procedures of the surveillance of surgical site infection (SSI) as stated by nosocomial infections surveillance systems in the United States and in Germany. Periprosthetic SSI can manifest itself after a long period.

METHODS

Seven hundred fifty-six orthopedic patients from 2 centers were evaluated after HPRO (n = 508) or KPRO (n = 248). SSI was recorded during hospitalization and for 12 month postdischarge. The surveillance regimen was extended by also sending patients a questionnaire after 12 months postdischarge. All complaints were followed up by contacting the patients and any clinicians and general practitioners (GPs) involved. Stratified infection rates and standardized infection ratio (SIR) were calculated and compared with reference data of the national surveillance system.

RESULTS

The total response rate to the postal questionnaire survey was 85.2%. SSI was recorded in 16 patients (3.15%) after HPRO; 12 were detected by predischarge surveillance, and the 4 cases found postdischarge were all organ/space SSI. In total, only 1 SSI was detected after KPRO before discharge and none after discharge (SSI rate 0.40%). Time between discharge and detection of SSI cases ranged from 8 days to 8 months. SIR of HPRO was 1.25 and SIR of KPRO was 0.36.

CONCLUSION

Because 25% of SSIs after HPRO occurred after discharge and all were organ/space SSI, highlights the importance of postdischarge surveillance of nosocomial infections (NIs). Because all SSIs were reported already by current surveillance, the extended postdischarge surveillance appears to be unnecessary. The pursuit of shorter hospital stay after surgery may challenge the methods of surveillance systems in future.

Enhanced identification of postoperative infections among outpatients

Claims data complement other data sources for identification of surgical site infections following breast surgery and cesarean section.

We investigated using administrative claims data to identify surgical site infections (SSI) after breast surgery and cesarean section. Postoperative diagnosis codes, procedure codes, and pharmacy information were automatically scanned and used to identify claims suggestive of SSI ("indicators") among 426 (22%) of 1,943 breast procedures and 474 (10%) of 4,859 cesarean sections. For 104 breast procedures with indicators explained in available medical records, SSI were confirmed for 37%, and some infection criteria were present for another 27%. Among 204 cesarean sections, SSI were confirmed for 40%, and some criteria were met for 27%. The extrapolated infection rates of 2.8% for breast procedures and 3.1% for cesarean section were similar to those reported by the National Nosocomial Infection Surveillance program but differ in representing predominantly outpatient infections. Claims data may complement other data sources for identification of surgical site infections following breast surgery and cesarean section.

Nosocomial infection surveillance and control policies

PURPOSE OF REVIEW

In the majority of countries costs for health care are increasing and strategies to reduce adverse events in medical treatment have an increasing importance. Nosocomial infection remains the most common type of complication affecting hospitalized patients. As preventive strategies have indeed become more important they now have to show not only that they are effective in reducing nosocomial infections but also that they are cost effective. This paper investigates the contribution made by articles published in the last year to the development of nosocomial-infection surveillance and control policies.

RECENT FINDINGS

At least 15 randomized controlled studies and six meta-analyses investigating various infection-control policies were published last year. They did not lead to any changes in present guidelines, but rather endorsed existing recommendations. At least nine studies were found reporting a substantial reduction in nosocomial infections by the introduction of quality management principles under routine working conditions. Furthermore there were a lot of studies published which focused on optimizing surveillance measures and investigating the use of reference data for reducing infection rates. Only seven studies estimating the burden of disease were found in the literature of the past year.

SUMMARY

The predominant opinion voiced in the studies was that in many medical institutions some 30% or more of nosocomial infections could be prevented.