Surgical-site infections after orthopaedic surgery: statewide surveillance using linked administrative databases

How accurately is hospital acquired pneumonia documented for the correct assignment of a hospital acquired complication (HAC)?

BACKGROUND

In 2016, the Australian Commission on Safety and Quality in Healthcare (ACSQHC) released a list of 16 categories of potentially preventable, high impact hospital-acquired complications (HAC) identified by using administrative coded data (ACD). An important category are hospital-acquired infections (HAI). Within this category, hospital-acquired pneumonia (HAP) is among the most frequent complications documented. There are no published studies concerning the current ACSQHC approach to HAI surveillance using ACD and no pneumonia-specific ACD studies reported from Australia. Published work indicates that ACD detection of HAP has low a sensitivity and positive predictive value (PPV). The current study was designed to examine whether coders correctly reflected the documentation of HAP that was present in the medical record and also evaluated the medical documentation that was present.

METHODS

One hundred patients with ACD encoded HAP were selected for review, drawn from admissions to 2 Hunter New England Health hospitals during 2017. Patient records and the eMR were reviewed by two medical officers to assess medical and radiological documentation of pneumonia. The district coding manager reviewed the accuracy of coding of a subset of 23 cases where medical review had not located documented evidence of HAP.

RESULTS

Of the 100 reviewed cases, the median patient age was 75 years (range 0-95 years) with 3% under 16 years of age. Twenty one were intensive care-associated of which 13 were associated with ventilation. In 23 cases the documentation was disputed and a secondary review took place - the coding manager confirmed coding changes in 14 of these 23 cases.

CONCLUSIONS

This study found that administrative coded data of HAP, utilizing the ACSQHC method reliably reflected the available documentation with a PPV of 86% (95% binomial exact confidence interval 77-92%), much higher than documented by previous ACD studies. The actual documentation of pneumonia by medical staff frequently used the non-specific term 'lower respiratory infection (LRTI)' which we recommend to be avoided. Radiological confirmation was absent in one third of cases. We recommend the adoption of a medical note template checklist for HAP to prompt clinicians with the accepted diagnostic criteria. We also recommend documenting a reason as to why any antibiotic has been commenced in a hospitalized patient in accord with the ACSQHC Antimicrobial Stewardship Clinical Care Standard.

Cervical re-explorations and proxy survival following parathyroidectomy for primary hyperparathyroidism using Australian administrative data

BACKGROUND

Administrative data may have utility in the impartial assessment of surgical outcomes and rare events. We have used a publicly available sample of the Australian pharmaceutical and health service provision (medical benefits scheme) databases to assess outcomes following parathyroidectomy for primary hyperparathyroidism (PHP).

METHODS

A cohort study using linked pharmaceutical and medical benefits schemes data was performed covering the period 1993-2014. Procedure codes identified participants undergoing parathyroidectomy for PHP and subsequent cervical re-exploration surgery (CRX), and the last service date used as a proxy for survival. Time to CRX and survival were modelled using Kaplan-Meier analysis. Demographic data and the era of parathyroid surgery were managed as covariates for Cox regression survival analyses.

RESULTS

A total of 2165 persons undergoing parathyroidectomy for PHP were identified. Median follow-up was 5.3 years (range 0.2-22). The annual number of parathyroidectomies for PHP increased gradually; 72 individuals underwent CRX (3.3%). The median time to CRX was 152 days (confidence interval 0-396) in 2000-2004 reducing to 47 days (confidence interval 15-78) for the period 2010-2014 (log-rank P = 0.027). The proportion of persons requiring CRX reduced over time from 6.1% in 1997 to 2.1% in 2012 (r²  = 0.5817, P = 0.023). Overall median survival (24.6 years) was poorer when compared with age matched controls (log-rank P = 0.025) but was not associated with CRX or gender.

CONCLUSION

Administrative data can be used for the assessment of surgical outcomes and may be useful for comparisons of surgical performance, and the appraisal of infrequent events. CRX rates following parathyroidectomy for PHP are improving in Australia.

Preoperative Low Molecular Weight Heparin as Venous Thromboembolism Prophylaxis in Patients at Risk for Prosthetic Infection After Knee Arthroplasty

Objective:

To investigate the effect of preoperative initiation of low molecular weight heparin as prophylaxis for deep venous thrombosis in patients at risk of developing surgical-site infections after knee arthroplasty.

Design:

Case–control study nested in a cohort. The incidence of surgical-site infection in the cohort was calculated. With the use of data extracted from medical histories and after adjustment for other risk factors, the effect of preoperative heparinization on the risk of incisional and prosthetic infection among case-patients and control-patients (1:3 ratio) was assessed.

Setting:

Orthopedic department in a tertiary-care referral hospital.

Patients:

A cohort of 160 consecutive patients who had received prosthetic knee implants between October 1, 2001, and November 30, 2003.

Results:

Eighteen patients with surgical-site infections were identified, yielding an incidence of incisional and prosthetic infection of 6.9 (95% confidence interval [CI95], 3.5 to 12.0) and 4.4 (CI95,1.8 to 8.8) cases per 100 patients undergoing surgery, respectively. Surgical-site infection was associated with preoperative use of low molecular weight heparin (odds ratio [OR], 6.2 after adjustment for medical and surgical factors; CI95, 1.5 to 23). Prosthetic infection was strongly associated with preoperative use of prophylaxis (OR, undetermined [100% exposure in case-patients vs 35% exposure in control-patients]; P = .002), but incisional surgical-site infection was not.

Conclusion:

The use of low molecular weight heparins immediately before knee arthroplasty as prophylaxis for deep venous thrombosis should be questioned because of probable increased risk of prosthetic infection.

Predicting Infections After Total Joint Arthroplasty Using a Prescription Based Comorbidity Measure

This study evaluated the association and predictive ability of co-morbidities measured by RxRisk-V, Elixhauser and Charlson measures and post-total hip (THA) and total knee arthroplasties (TKA) infection. THAs and TKAs (2001-2012) were identified using the Australian Department of Veterans' Affairs data. Infections within 90 days post-surgery were the study endpoint. Co-morbidities were identified using pharmacy (RxRisk-V) and hospitalization history (Elixhauser, Charlson). Of the 11,848 THAs, 3.1% (N = 364) had infections and out of 18,972 TKAs 3.4% (N = 648). Comorbidity burden and specific conditions were associated with infection likelihood. RxRisk-V performed better than other measures, but none had high predictive ability and differences were small. The best performing infection prediction models resulted when a combination of conditions identified by all measures was used.

Epidemiology of surgical site infections after total hip and knee joint replacement during 2007-2009: a report from the VINCat Program

The VINCat Program is a system for epidemiological surveillance of healthcare-related infections in which the majority of Catalan hospitals participate. It has a specific module for surgical site infections (SSI) surveillance. Primary hip and knee arthroplasties are basic indicators of the program due to their high frequency and the important morbidity of SSI of these sites. Results are presented for surgical site infection (SSI) surveillance of primary hip and knee arthroplasties for the first three years of the VINCat Program. The program requires SSI surveillance to be performed in a standardized, prospective and continuous manner by an infection control team from the centers. With primary arthroplasties, as with all procedures involving implants, the surveillance is maintained for 1 year after the intervention. The VINCat Program uses the SSI definitions of the Centers for Disease Control (CDC) and patients are stratified by surgical risk, following the classification of the National Healthcare Safety Network (NHSN). During the period 2007-2009, 51 Catalan hospitals participated in the SSI surveillance of prosthetic orthopedic surgery. The overall SSI rate in the interventions for total primary hip prosthesis (7,804 procedures) was 3.0% (IC 95%: 2.6-3.4) and for total primary knee prosthesis (16,781 procedures) was 3.3% (IC95%: 3.0-3.6). During the period 2007-2009, the overall SSI rates for total primary hip and knee arthroplasty were higher than those published by some surveillance systems in our environment. There were significant differences in the infection rates by procedure and in those adjusted by risk among the different hospitals.

Decreasing time trend in SSI incidence for orthopaedic procedures: surveillance matters!

BACKGROUND

Infection is the most common reason for early revision after hip and knee arthroplasty, and the revision rate is increasing. Surgical site infection (SSI) surveillance data are important to assess the true infection rate. There is little information regarding the potential time trend in SSI incidence following orthopaedic surgery.

AIM

To evaluate whether a time trend exists in SSI incidence due to surveillance following orthopaedic surgery.

METHODS

The SSI rates after hip and knee replacements and osteosynthesis of trochanteric femoral fractures and ankle fractures were recorded prospectively from May 1998 to October 2008 according to the criteria of the US Centers for Disease Control and Prevention. In total, 4177 procedures were analysed, 65.8% of which were performed on female patients. Linear regression was used to analyse trends in SSI rates.

FINDINGS

SSI incidence decreased significantly from 7% in the first year to 3% in the last year; a 57% relative reduction. The duration of surgery was the only significant predictor for infection (P < 0.001) in a logistic regression model that also included age, American Society of Anesthesiologists' score and level of emergency.

CONCLUSION

Surveillance following orthopaedic procedures showed a significant decrease in SSI incidence over the 11-year surveillance period. The causality between surveillance and SSI incidence is difficult to prove, but surveillance with feedback probably influences several procedures that affect the quality of health care, even if duration of surgery is the only significant predictor of this effect.

Does dual antibiotic prophylaxis better prevent surgical site infections in total joint arthroplasty?

INTRODUCTION

It is unclear which antibiotic regimen provides the best prophylaxis against surgical site infection (SSI) in patients undergoing hip and knee surgery.

QUESTIONS/PURPOSES

Therefore, we determined whether dual antibiotic prophylaxis (1) reduced the rate of SSI compared to single antibiotic prophylaxis and (2) altered the microbiology of SSI.

METHODS

We retrospectively reviewed 1828 primary THAs and TKAs performed between September 1, 2008 and December 31, 2010. We divided patients into two groups: (1) those who received a dual prophylactic antibiotic regimen of cefazolin and vancomycin (unless allergy), or (2) received cefazolin (unless allergy) as the sole prophylactic antibiotic. There were 701 males and 1127 females with an average age of 56 years (range, 15–97 years). We limited followup to 1 year, presuming subsequent infections were not related to the initial surgery.

RESULTS

During this period, there were 22 SSIs (1.2%). The infection rates for dual antibiotic prophylaxis compared to a single antibiotic regimen were 1.1% and 1.4%, respectively. Of 1328 patients treated with dual antibiotic prophylaxis, only one (0.08%) SSI was culture positive for methicillin resistant Staphylococcus aureus (MRSA), while four of 500 patients (0.8%) receiving only cefazolin prophylaxis had culture positive MRSA infection at the time of reoperation.

CONCLUSION

The addition of vancomycin as a prophylactic antibiotic agent apparently did not reduce the rate of SSI compared to cefazolin alone. Use of vancomycin in addition to cefazolin appeared to reduce the incidence of MRSA infections; however, the number needed to treat to prevent a single MRSA infection was very high.

LEVEL OF EVIDENCE

Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Total knee arthroplasty volume, utilization, and outcomes among Medicare beneficiaries, 1991-2010

CONTEXT

Total knee arthroplasty (TKA) is one of the most common and costly surgical procedures performed in the United States.

OBJECTIVE

To examine longitudinal trends in volume, utilization, and outcomes for primary and revision TKA between 1991 and 2010 in the US Medicare population.

DESIGN, SETTING, AND PARTICIPANTS

Observational cohort of 3,271,851 patients (aged ≥65 years) who underwent primary TKA and 318 563 who underwent revision TKA identified in Medicare Part A data files.

MAIN OUTCOME MEASURES

We examined changes in primary and revision TKA volume, per capita utilization, hospital length of stay (LOS), readmission rates, and adverse outcomes.

RESULTS

Between 1991 and 2010 annual primary TKA volume increased 161.5% from 93,230 to 243,802 while per capita utilization increased 99.2% (from 31.2 procedures per 10,000 Medicare enrollees in 1991 to 62.1 procedures per 10,000 in 2010). Revision TKA volume increased 105.9% from 9650 to 19,871 while per capita utilization increased 59.4% (from 3.2 procedures per 10,000 Medicare enrollees in 1991 to 5.1 procedures per 10,000 in 2010). For primary TKA, LOS decreased from 7.9 days (95% CI, 7.8-7.9) in 1991-1994 to 3.5 days (95% CI, 3.5-3.5) in 2007-2010 (P < .001). For primary TKA, rates of adverse outcomes resulting in readmission remained stable between 1991-2010, but rates of all-cause 30-day readmission increased from 4.2% (95% CI, 4.1%-4.2%) to 5.0% (95% CI, 4.9%-5.0%) (P < .001). For revision TKA, the decrease in hospital LOS was accompanied by an increase in all-cause 30-day readmission from 6.1% (95% CI, 5.9%-6.4%) to 8.9% (95% CI, 8.7%-9.2%) (P < .001) and an increase in readmission for wound infection from 1.4% (95% CI, 1.3%-1.5%) to 3.0% (95% CI, 2.9%-3.1%) (P < .001).

CONCLUSIONS

Increases in TKA volume have been driven by both increases in the number of Medicare enrollees and in per capita utilization. We also observed decreases in hospital LOS that were accompanied by increases in hospital readmission rates.

Thromboprophylaxis, bleeding and post-operative prosthetic joint infection in total hip and knee arthroplasty: a comprehensive literature review

INTRODUCTION

Concerns regarding risk versus benefit, that is, the possible impact of surgical-site bleeding on post-operative joint infections, have contributed to a continuing debate over recommendations for venous thromboembolism (VTE) prophylaxis in post-surgical orthopedic patients undergoing total hip and knee arthroplasty (THA/TKA).

AREAS COVERED

A comprehensive literature search using MEDLINE covering the period 2004-2009 was conducted, and published studies that focused on THA and TKA and contained data applicable to thromboprophylaxis, post-surgical wound infection and bleeding are reviewed in this paper. The search strategy included various combinations of terms related to lower limb joint arthroplasty, anticoagulant drugs, post-operative bleeding and prosthetic joint infection (wound infection). Methodological constraints included failure in some studies to define an infection, variations among the studies in the definitions of bleeding and differences in the follow-up time for capturing infection and bleeding events. Despite this, this comprehensive review identified observational, 'real-world' data that can contribute in important ways to the existing evidence base.

EXPERT OPINION

There are insufficient data to either confirm or refute the hypothesis that post-operative bleeding is a mediating pathophysiologic factor linking pharmacologic VTE prophylaxis to an increased risk for wound infection. Studies specifically designed to examine the interrelationship between thromboprophylaxis, bleeding and wound infections following THA/TKA are warranted.

Relative risk of different operations for medial compartment osteoarthritis of the knee

The relative risk of total knee arthroplasty (TKA), high tibial osteotomy (HTO), and medial unicompartment (UKA) replacement for medial compartment arthritis is presented. Risk is defined as the product of the probability of an event occurring and its consequence. To define consequence, 2 related scales of impact (1 systemic and 1 local) are suggested. The probability of a complication is derived from the incidence as found in the published literature and expressed as a decimal of 1. The cumulative risk is expressed as the sum of the risks of all individual complications. The overall impact of specific comorbidities has been calculated when their influence on the incidence of a particular complication is known. Of the 3 operations, TKA has the highest cumulative risk of systemic complications and HTO is the most likely to produce local technical problems. UKA is the safest of the procedures. The relative risk of TKA:HTO:UKA is 1.00:1.01:0.31. For TKA, the greatest additional risk is morbid obesity, which increases overall risk by 31% by virtue of a 7.8-fold increase in infection rate. Cardiorespiratory disease, diabetes mellitus, smoking, and cirrhosis of the liver increase cumulative risk by 20%, 17%, and 17%, respectively.The authors conclude that a quantitative assessment of operative risk is possible and useful. However, it depends on the availability of reliable complication incidence data.

Timing of DVT prophylaxis and risk of postoperative knee prosthesis infection

This multicenter prospective study was performed to determine risk factors for knee prosthesis infection and the effect of timing doses of prophylactic low-molecular-weight heparins (LMWH) related to time of surgery on the risk of knee prosthesis infection. A total of 5496 consecutive patients who underwent total knee arthroplasty from 2005 to 2006 in 13 orthopedic centers were prospectively followed up for 6 months, and the incidence of knee prosthesis infection was recorded. A case control study was nested in the cohort. Case patients were matched to uninfected (control) patients, and the timing of perioperative LMWH was recorded as the main risk factor. Fifty patients developed postoperative knee prosthesis infection during the follow-up period, yielding an incidence of prosthesis infection of 0.91% (95% CI, 0.68%-1.20%). Forty-four patients were matched to 106 controls. Case patients received the first LMWH dose ±12 hours from the start of surgery more frequently than their control counterparts (odds ratio, 1.5; 95% CI, 0.73-3.0). After adjusting by main risk factors, no statistical association was found between close perioperative timing of LMWH and risk of prosthesis infection. Diabetes mellitus (adjusted odds ratio, 3.2; 95% CI, 1.2-8.8) and wound hematoma (adjusted odds ratio, 4.2; 95% CI, 1.1-16.5) were found to be independent risk factors for prosthesis infection.

Relationship between perioperative urinary tract infection and deep infection after joint arthroplasty

Surgical wound infection is a serious and potentially catastrophic complication after joint arthroplasty. Urinary tract infection is a common infection that creates a potential reservoir of resistant pathogens and increases patient morbidity. We asked whether treated preoperative and postoperative urinary tract infections are risk factors for deep joint infection. We examined the medical records of 19,735 patients. The minimum had joint infections develop. Of these, three had preoperative and four had postoperative urinary tract infections. The majority of bacteria were not enteric. The bacteria in the two types of infections were not identical. Control subjects were randomly selected from a list of patients matched with patients having infections. Of these, eight had preoperative and one had postoperative urinary tract infections. We found no association between the preoperative urinary tract infection (odds ratio, 0.341; 95% confidence interval, 0.086-1.357) or postoperative urinary tract infection (odds ratio, 4.222; 95% confidence interval, 0.457-38.9) and wound infection. Only one of the 58 patients with wound infections had a urinary tract infection with the same bacteria in both infections. Given the infection rate was very low (0.29%), the power of the study was only 25%. Although limited, the data suggest patients with urinary tract infections had no more likelihood of postoperative infection. We believe treated urinary tract infection should not be a reason to delay or postpone surgery.

LEVEL OF EVIDENCE

Level III, therapeutic study.

[Surgical-site infections following varicose vein surgery according to a continuous series of 408 interventions in a teaching hospital]

OBJECTIVE

To determine the incidence of surgical-site infections (SSI) following varicose vein surgery in the vascular surgery ward of a French teaching hospital.

PATIENTS AND METHODS

A prospective surveillance of SSI was conducted during one year, with a 30-day postoperative follow-up. SSI cases were identified by using the definitions of the Centers for Disease Control (CDC, USA). Data acquisition and analysis were performed with the Epi-Info 6.04 software (CDC).

RESULTS

Three quarters of the 408 included interventions were characterized by a NNIS score equal to 0. All patients underwent a hair removing practice before intervention. Hair removing methods were very heterogeneous and often not in accordance with national recommendations (e.g. mechanic shaving for 44.6% of patients). The incidence of SSI was 1.2% (95% confidence interval=[0.2-2.2]). All infections were identified after hospital discharge. Four infected patients out of five presented obesity or excess weight, and two patients had diabetes mellitus. The mean age of infected patients was significantly higher than non-infected ones (70.4 years versus 52.0; p<0.01). All SSI had consequences like rehospitalization, reintervention, or antimicrobial therapy.

CONCLUSION

According to our results, SSI following varicose vein surgery are scarce and mainly concerned high-risk patients. However, in an aim of prevention, it seems necessary to homogenize hair removing methods in this ward.

A technology ecosystem perspective on hospital management information systems: lessons from the health literature

Hospital managers have a large range of information needs including quality metrics, financial reports, access information needs, educational, resourcing and decision support needs. Currently these needs involve interactions by managers with numerous disparate systems, both electronic such as SAP, Oracle Financials, PAS' (patient administration systems) like HOMER, and relevant websites; and paper-based systems. Hospital management information systems (HMIS) can be thought of sitting within a Technology Ecosystem (TE). In addition, Hospital Management Information Systems (HMIS) could benefit from a broader and deeper TE model, and the HMIS environment may in fact represents its own TE (the HMTE). This research will examine lessons from the health literature in relation to some of these issues, and propose an extension to the base model of a TE.

Outcomes in patients with an emergency department diagnosis of fever of unknown origin

OBJECTIVE

To describe the outcomes in patients given an ED diagnosis of fever of unknown origin (FUO).

METHODS

A retrospective analysis of ED records linked to hospital morbidity, mortality and microbiology records of patients presenting to Western Australia's teaching hospitals from July 2000 to July 2003.

RESULTS

There were 3218 presentations diagnosed with FUO, 2049 (63.7%) children (median age 1.8 years) and 1169 (36.3%) adults (median age 56.0 years). FUO accounted for 0.3% of adult and 1.5% of paediatric ED presentations. Overall, 1997 (62.1%, 95% confidence interval 60.4-63.8%) were admitted (82% adults vs 50.7% children; P < 0.001). Adults had a longer median length of stay than children (4 days vs 2 days; P < 0.001) and a higher proportion of positive blood cultures (admissions 15.1%vs 4.9%; P < 0.001) commonly with Escherichia coli. Streptococcus pneumoniae was the most common organism isolated from children. Of 3053 FUO index presentations, 338 (11.1%, 95% confidence interval 10.0-12.2%) re-presented. Children were more likely to re-present than adults (13.5% of 1959 vs 6.8% of 1094; P < 0.001).

CONCLUSIONS

Fever of unknown origin is diagnosed less frequently in adults than in children. Adult patients are more likely to be admitted, have longer lengths of stay and have positive blood cultures. Although FUO is diagnosed infrequently in the ED, blood cultures remain useful in the evaluation of unexplained fever, particularly in adults as age increases.

Staphylococcus aureus, the major pathogen in orthopaedic and cardiac surgical site infections: a literature review

Due to the increasing number of orthopaedic and cardiac procedures, these units are considered as high-risk areas because of the potentially serious consequences of surgical site infections (SSI), primarily caused by Staphylococcus aureus. The goal of this review was to evaluate the impact of S. aureus on the incidence of SSI in these high risk wards. Studies were identified by a search on the MEDLINE literature using the following mesh terms: S. aureus, cardiac, orthopaedic, surgery, SSI. Beside, data from different surveillance systems were also included. Overall, biological investigation was performed only on a small proportion of identified SSIs. Of those identified, S. aureus represented the most common pathogen accounting for approximately 20% of all SSIs. Of the 59,274 hip prostheses reported from the HELICS surveillance network, S. aureus formed 48.6% of the pathogens (416 bacteria isolated). Similarly, it represented 43.7% of pathogens after coronary artery bypass grafting. Although S. aureus turned out to be the major pathogen, this work identifies the relative lack of knowledge on the overall incidence of S. aureus infections and on the impact of this pathogenic agent when taking into consideration the degree of wound contamination and category of SSI. There is a need for more detailed information on the role of S. aureus in the burden of surgical site infections and consequently how to establish multiple approach prevention programs.

The bacteriology of pneumonia diagnosed in Western Australian emergency departments

We used Western Australian emergency department data linked to hospital morbidity, death and microbiology data to describe the bacteriology of pneumonia according to age. The 'atypical' organisms and viruses were not assessed. A total of 6908 patients over a 3-year period were given an emergency department diagnosis of pneumonia, 76.9% were admitted and 6.3% died in hospital. Blood was cultured from 52.9% of patients with 6.4% growing potential pathogens. Streptococcus pneumoniae was the most common organism isolated and accounted for 92% of pathogens in those aged <15 years. Isolation of Enterobacteriaceae species tended to increase with age and accounted for around 25% of isolates from the elderly. Sputum was cultured from 25.3% of patients and bacteria were isolated from 30.3% of samples, commonly Haemophilus influenzae and S. pneumoniae. Isolates from sputum showed no distinct trend across age groups. These patterns question the value of routine blood and sputum cultures and have implications for empiric therapy for the elderly.

Impact of postdischarge surveillance on the rate of surgical site infection after orthopedic surgery

OBJECTIVE

To evaluate the impact of postdischarge surveillance on surgical site infection (SSI) rates after orthopedic surgery.

SETTING

Nine hospitals participating in the Finnish Hospital Infection Program.

PATIENTS

All patients who underwent hip or knee arthroplasty or open reduction of a femur fracture during 1999-2002.

RESULTS

The date of discharge was available for 11,812 procedures (90%). The median length of hospital stay was 8 days (range per hospital, 6-9 days). The overall SSI rate was 3.3% (range, 0.8%-6.4%). Of 384 SSIs detected, 216 (56%; range, 28%-90%) were detected after discharge: 93 (43%) were detected on readmission to the hospital, 73 (34%) at completion of a postdischarge questionnaire, and 23 (11%) at a follow-up visit. For 27 postdischarge SSIs (13%), the location of detection was unknown. Altogether, 32 (86%) of 37 of organ/space SSIs, 57 (80%) of 71 deep incisional SSIs, and 127 (46%) of 276 superficial incisional SSIs were detected after discharge. Most SSIs (70%) detected on readmission were severe (organ/space or deep incisional), whereas most SSIs (86%) detected at follow-up visits or at completion of a postdischarge questionnaire were superficial. Of all SSIs, 78% (range, 48%-100%) were microbiologically confirmed. Microbiologic confirmation was less common after discharge than during postoperative hospital stay (66% vs 93%; P<.001).

CONCLUSIONS

Postdischarge surveillance had a large impact on the rate of SSI detected after orthopedic surgery. However, postdischarge surveillance conducted by means of a questionnaire detected only a minority of deep incisional and organ/space SSIs.

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.

Engineering approaches for the detection and control of orthopaedic biofilm infections

Artificial joints are subject to chronic infections associated with bacterial biofilms, which only can be eradicated by the traumatic removal of the implant followed by sustained intravenous antibiotic therapy. We have adopted an engineering approach to develop electrical-current-based approaches to bacterial eradication and microelectromechanical systems that could be embedded within the implanted joint to detect the presence of bacteria and to provide in situ treatment of the infection before a biofilm can form. In the former case we will examine the combined bactericidal effects of direct and indirect electrical fields in combination with antibiotic therapy. In the latter case, bacterial detection will occur by developing a microelectromechanical-systems-based biosensor that can "eavesdrop" on bacterial quorum-sensing-based communication systems. Treatment will be effected by the release of a cocktail of pharmaceutical reagents contained within integral reservoirs associated with the implant, including a molecular jamming signal that competitively binds to the bacteria's quorum sensing receptors (which will "blind" the bacteria, preventing the production of toxins) and multiple high dose antibiotics to eradicate the planktonic bacteria. This approach is designed to take advantage of the relatively high susceptibility to antibiotics that planktonic bacteria display compared with biofilm envirovars. Here we report the development of a generic microelectromechanical systems biosensor that measures changes in internal viscosity in a base fluid triggered by a change in the external environment.

Linkage of microbiology reports and hospital discharge diagnoses for surveillance of surgical site infections

Surveillance of surgical site infections (SSIs) with feedback to surgical personnel is pivotal in decisions regarding infection control. Prospective surveillance is time and resource consuming, so we aimed to evaluate a method based on data collected routinely during care delivery. The study was carried out at three acute hospitals in North-eastern Italy, from 1 January 2001 to 31 December 2001. Hospital discharge diagnoses (selected codes from the International Classification of Diseases, 9th Revision--Clinical Modification) and electronic microbiology reports (positive cultures from surgical wounds and drainages) were linked to identify suspected SSIs. A random sample of tracked events was submitted to total chart review in order to confirm the presence of SSIs retrospectively according to Centers for Disease Control and Prevention definitions. Of 865 suspected SSIs, 64.5% were identified from the microbiological database, 27.1% from discharge codes, and 8.4% from both. Four hundred and three admissions were sampled for review; the overall positive predictive value was 72% (95%CI=69-76%). Since inpatient individual antibiotic exposure is not registered in Italy, the combined use of discharge codes and microbiology reports represents the most feasible automated method for surveillance of SSIs developing during hospital stay.

Costs associated with hospital-acquired bacteraemia in a Belgian hospital

Studies from around the world have shown that hospital-acquired infections increase the costs of medical care due to prolongation of hospital stay, and increased morbidity and mortality. The aim of this study was to determine the extra costs associated with hospital-acquired bacteraemias in a Belgian hospital in 2001 using administrative databases and, in particular, coded discharge data. The incidence was 6.6 per 10000 patient days. Patients with a hospital-acquired bacteraemia experienced a significantly longer stay (average 21.1 days, P<0.001), a significantly higher mortality (average 32.2%, P<0.01), and cost significantly more (average 12853 euro, P<0.001) than similar patients without bacteraemia. At present, the Belgian healthcare system covers most extra costs; however, in the future, these outcomes of hospital-acquired bacteraemia will not be funded and prevention will be a major concern for hospital management.