Compliance with Australian Orthopaedic Association guidelines does not reduce the risk of venous thromboembolism after total hip and knee arthroplasty.

Preventing avoidable venous-thrombo-embolism (VTE) is a priority to improve patient and service outcomes after total hip and total knee arthroplasty (THA, TKA), but compliance with relevant clinical guidelines varies. This study aims to determine the degree to which prophylaxis was compliant with Australian Orthopaedic Association (AOA) VTE prophylaxis guidelines and whether non-compliance is associated with increased risk of VTE. A prospective multi-centre cohort study of adults with osteoarthritis undergoing primary TKA/THA was completed at 19 high-volume public and private hospitals. Data were collected prior to surgery and for one-year post-surgery. Logistic regression was undertaken to explore associations between non-compliance with AOA VTE prophylaxis guidelines and symptomatic 90-day VTE outcomes. Data were analysed for 1838 participants from 19 sites. The rate of non-compliance with all clinical guideline recommendations was 20.1% (N = 369), with 14.1% (N = 259) non-compliance for risk-stratified prophylaxis, 35.8% (N = 658) for duration, and 67.8% (N = 1246) for other general recommendations. Symptomatic VTE was experienced up to 90-days post-surgery by 48 people (2.6%). Overall guideline non-compliance (AOR = 0.93, 95%CI = 0.4 to 1.3, p = 0.86) was not associated with a lower risk of symptomatic 90-day VTE. Results were consistent when people with high bleeding risk were excluded (AOR = 0.94, 95%CI = 0.44 to 2.34, p = 0.89). Non-compliance with the AOA VTE prophylaxis guidelines was not associated with risk of 90-day VTE after arthroplasty. This counterintuitive finding is concerning and necessitates a rigorous review of the AOA VTE prevention clinical guideline.

Association between VTE and antibiotic prophylaxis guideline compliance and patient-reported outcomes after total hip and knee arthroplasty: an observational study.

BACKGROUND: Surgical site infection (SSI) and venous thromboembolism (VTE) are associated with high burden and cost and are considered largely preventable following total knee or hip arthroplasty (TKA, THA). The risk of developing VTE and SSI is reduced when prophylaxis is compliant with evidence-based clinical guidelines. However, the association between VTE and antibiotic prophylaxis clinical guideline compliance and patient-reported outcome measures (PROMs) after THA/TKA is unknown. This study aims to explore whether care that is non-compliant with VTE and antibiotic guideline recommendations is associated with PROMs (Oxford Hip/Knee Score and EQ-5D Index scores) at 90- and 365-days after surgery. METHODS: This prospective observational study included high-volume arthroplasty public and private sites and consenting eligible participants undergoing elective primary THA/TKA. We conducted multiple linear regression and linear mixed-effects modelling to explore the associations between non-compliance with VTE and antibiotic guidelines, and PROMs. RESULTS: The sample included 1838 participants. Compliance with VTE and antibiotic guidelines was 35% and 13.2% respectively. In adjusted modelling, non-compliance with VTE guidelines was not associated with 90-day Oxford score (ß = - 0.54, standard error [SE] = 0.34, p = 0.112) but was significantly associated with lower (worse) 365-day Oxford score (ß = - 0.76, SE = 0.29, p = 0.009), lower EQ-5D Index scores at 90- (ß = - 0.02 SE = 0.008, p = 0.011) and 365-days (ß = - 0.03, SE = 0.008, p = 0.002).. The changes in Oxford and EQ-5D Index scores were not clinically important. Noncompliance with antibiotic guidelines was not associated with either PROM at 90- (Oxford: ß = - 0.45, standard error [SE] = 0.47, p = 0.341; EQ-5D: ß = - 0.001, SE = 0.011, p = 0.891) or 365-days (Oxford score: ß = - 0.06, SE = 0.41, p = 0.880 EQ-5D: ß = - 0.010, SE = 0.012, p = 0.383). Results were consistent when complications were included in the model and in linear mixed-effects modelling with the insurance sector as a random effect. CONCLUSIONS: Non-compliance with VTE prophylaxis guidelines, but not antibiotic guidelines, is associated with statistically significant but not clinically meaningful differences in Oxford scores and EQ-5D Index scores at 365 days.

Modelling vaccination capacity at mass vaccination hubs and general practice clinics: a simulation study.

BACKGROUND: COVID-19 mass vaccination programs place an additional burden on healthcare services. We aim to model the queueing process at vaccination sites to inform service delivery. METHODS: We use stochastic queue network models to simulate queue dynamics in larger mass vaccination hubs and smaller general practice (GP) clinics. We estimate waiting times and daily capacity based on a range of assumptions about appointment schedules, service times and staffing and stress-test these models to assess the impact of increased demand and staff shortages. We also provide an interactive applet, allowing users to explore vaccine administration under their own assumptions. RESULTS: Based on our assumed service times, the daily throughput for an eight-hour clinic at a mass vaccination hub ranged from 500 doses for a small hub to 1400 doses for a large hub. For GP clinics, the estimated daily throughput ranged from about 100 doses for a small practice to almost 300 doses for a large practice. What-if scenario analysis showed that sites with higher staff numbers were more robust to system pressures and mass vaccination sites were more robust than GP clinics. CONCLUSIONS: With the requirement for ongoing COVID-19 booster shots, mass vaccination is likely to be a continuing feature of healthcare delivery. Different vaccine sites are useful for reaching different populations and maximising coverage. Stochastic queue networks offer a flexible and computationally efficient approach to simulate vaccination queues and estimate waiting times and daily throughput to inform service delivery.

Non-compliance with clinical guidelines increases the risk of complications after primary total hip and knee joint replacement surgery.

BACKGROUND: Total hip and total knee replacement (THR/TKR) are common and effective surgeries to reduce the pain and disability associated with arthritis but are associated with small but significant risks of preventable complications such as surgical site infection (SSI) and venous-thrombo-embolism (VTE). This study aims to determine the degree to which hospital care was compliant with clinical guidelines for the prevention of SSI and VTE after THR/TKR; and whether non-compliant prophylaxis is associated with increased risk of complications. METHODS AND FINDINGS: A prospective multi-centre cohort study was undertaken in consenting adults with osteoarthritis undergoing elective primary TKR/THR at one of 19 high-volume Australian public or private hospitals. Data were collected prior to surgery and for one-year post-surgery. Four adjusted logistic regression analyses were undertaken to explore associations between binary non-compliance and the risk of surgical complications: (1) composite (simultaneous) non-compliance with both (VTE and antibiotic) guidelines and composite complications [all-cause mortality, VTE, readmission/reoperation for joint-related reasons (one-year) and non-joint-related reasons (35-days)], (2) VTE non-compliance and VTE outcomes, (3) antibiotic non-compliance and any SSI, and (4) antibiotic non-compliance and deep SSI. Data were analysed for 1875 participants. Guideline non-compliance rates were high: 65% (VTE), 87% (antibiotics) and 95% (composite guideline). Composite non-compliance was not associated with composite complication (12.8% vs 8.3%, adjusted odds ratio [AOR] = 1.41, 95%CI 0.68-3.45, p = 0.40). Non-compliance with VTE guidelines was associated with VTE outcomes (5% vs 2.4%, AOR = 2.83, 95%CI 1.59-5.28,p < 0.001). Non-compliance with antibiotic guidelines was associated with any SSI (14.8% vs 6.1%, AOR = 1.98, 95%CI 1.17-3.62,p = 0.02) but not deep infection (3.7% vs 1.2%,AOR = 2.39, 95%CI 0.85-10.00, p = 0.15). CONCLUSIONS: We found high rates of clinical variation and statistically significant associations between non-compliance with VTE and antibiotic guidelines and increased risk of VTE and SSI, respectively. Complications after THR/TKR surgery may be decreased by improving compliance with clinical guidelines.

Cost of investigations during the acute hospital stay following total hip or knee arthroplasty, by complication status.

BACKGROUND: Total hip and total knee arthroplasties are among the most common types of surgery performed in Australia today and are effective treatments for severe osteoarthritis. However, the increasing financial burden on the health system owing to the increasing rates of surgery has led to a growing interest in improving the cost-effectiveness and safety of arthroplasty care. This study was designed to quantify the association between post-operative complications, a major cost driver, and the cost of investigations following total hip or knee arthroplasty. METHODS: This is a prospective cohort study of consecutive patients undergoing primary total hip or knee arthroplasty at an Australian public hospital. We measured the number and cost of imaging and pathology tests performed during the acute hospital stay and used linear regression to quantify the association between complication status and investigation costs. RESULTS: Five hundred patients were included in the analysis. On average, those with complications received more tests, and more expensive tests. The mean combined cost of imaging and pathology tests in patients with no complications was AU$ 187 (SD: 12.0). In comparison, patients with minor complications had a mean additional cost of AU$ 270 (SD: 31.0), and those with major complications had a mean additional cost of AU$ 493 (SD: 54.2) (p < 0.001). CONCLUSIONS: In patients undergoing hip or knee arthroplasty, investigation costs are substantially greater in the presence of either minor or major complications. With growing volumes of total hip and total knee arthroplasties, a potential focus of future research could include optimising investigation practices for patients with and without complications.

Wrist deformity, bother and function following wrist fracture in the elderly.

OBJECTIVE: Wrist deformity in older people is common following treatment for a wrist fracture, particularly after non-surgical treatment. A cohort of older wrist fracture patients were surveyed by telephone regarding perceived deformity, bother with deformity and patient-reported wrist function. The objectives were to: (1) determine whether older patients with wrist fractures perceived a deformity of their wrist and if they were bothered by it; (2) test if there were associations between deformity and treatment-type and between deformity and function; (3) test for associations between bother and treatment-type and between bother and function; (4) measure the test-retest reliability of the 'bother' question. RESULTS: Of 98 eligible patients who were invited to participate, 41 responded. Out of 41, 14 (34%) believed they had a deformity and 4 (10%) reported that they were bothered by the appearance of their wrist. Deformity was associated with non-surgical treatment (RR = 3.85, p = 0.006) but was not significantly associated with functional outcomes (p = 0.15). All those who were bothered belonged to the non-surgical treatment group. Bother was significantly associated with poorer functional outcomes (p = 0.006) and this association was clinically significant (MD = 35 points). The deformity and bother questions were found to have excellent test-retest reliability; κ = 1.00 and κ = 0.92, respectively.

Assessing privacy risks in population health publications using a checklist-based approach.

OBJECTIVE: Recent growth in the number of population health researchers accessing detailed datasets, either on their own computers or through virtual data centers, has the potential to increase privacy risks. In response, a checklist for identifying and reducing privacy risks in population health analysis outputs has been proposed for use by researchers themselves. In this study we explore the usability and reliability of such an approach by investigating whether different users identify the same privacy risks on applying the checklist to a sample of publications. METHODS: The checklist was applied to a sample of 100 academic population health publications distributed among 5 readers. Cohen's κ was used to measure interrater agreement. RESULTS: Of the 566 instances of statistical output types found in the 100 publications, the most frequently occurring were counts, summary statistics, plots, and model outputs. Application of the checklist identified 128 outputs (22.6%) with potential privacy concerns. Most of these were associated with the reporting of small counts. Among these identified outputs, the readers found no substantial actual privacy concerns when context was taken into account. Interrater agreement for identifying potential privacy concerns was generally good. CONCLUSION: This study has demonstrated that a checklist can be a reliable tool to assist researchers with anonymizing analysis outputs in population health research. This further suggests that such an approach may have the potential to be developed into a broadly applicable standard providing consistent confidentiality protection across multiple analyses of the same data.

Anonymization for outputs of population health and health services research conducted via an online data center.

OBJECTIVE: Online data centers (ODCs) are becoming increasingly popular for making health-related data available for research. Such centers provide good privacy protection during analysis by trusted researchers, but privacy concerns may still remain if the system outputs are not sufficiently anonymized. In this article, we propose a method for anonymizing analysis outputs from ODCs for publication in academic literature. METHODS: We use as a model system the Secure Unified Research Environment, an online computing system that allows researchers to access and analyze linked health-related data for approved studies in Australia. This model system suggests realistic assumptions for an ODC that, together with literature and practice reviews, inform our solution design. RESULTS: We propose a two-step approach to anonymizing analysis outputs from an ODC. A data preparation stage requires data custodians to apply some basic treatments to the dataset before making it available. A subsequent output anonymization stage requires researchers to use a checklist at the point of downloading analysis output. The checklist assists researchers with highlighting potential privacy concerns, then applying appropriate anonymization treatments. CONCLUSION: The checklist can be used more broadly in health care research, not just in ODCs. Ease of online publication as well as encouragement from journals to submit supplementary material are likely to increase both the volume and detail of analysis results publicly available, which in turn will increase the need for approaches such as the one suggested in this paper.

Quantifying under-reporting of pathology tests in Medical Benefits Schedule claims data.

OBJECTIVE: We investigated the completeness of recording of pathology tests in Australian Medical Benefits Schedule (MBS) claims data, using the example of the prostate-specific antigen (PSA) test. With some exceptions, MBS claims data records only the three most expensive pathology items in an episode of care, and this practice ('episode coning') means that pathology tests can be under-recorded. METHODS: The analysis used MBS data for male participants in the 45 and Up Study. The number and cost of items in each episode of care were used to determine whether an episode contained a PSA screening test (Item 66655), or could have lacked a record of this item because of episode coning. RESULTS: MBS data for 1070392 episodes involving a request for a pathology test for 118074 men were analysed. Of these episodes, 11% contained a request for a PSA test; a further 7.5% may have been missing a PSA request that was not recorded because of episode coning. CONCLUSIONS: It is important to consider under-reporting of pathology tests as a result of episode coning when interpreting MBS claims data. Episode coning creates uncertainty about whether a person has received any given pathology test. The extent of this uncertainty can be estimated by determining the proportion of episodes in which the test may have been performed but was not recorded due to episode coning.

The impact of compulsory helmet legislation on cyclist head injuries in New South Wales, Australia: a response.

This article responds to criticisms made in a rejoinder (Accident Analysis and Prevention 2012, 45: 107-109) questioning the validity of a study on the impact of mandatory helmet legislation (MHL) for cyclists in New South Wales, Australia. We systematically address the criticisms through clarification of our methods, extension of the original analysis and discussion of new evidence on the population-level effects of MHL. Extensions of our analysis confirm the original conclusions that MHL had a beneficial effect on head injury rates over and above background trends and changes in cycling participation. The ongoing debate around MHL draws attention away from important ways in which both safety and participation can be improved through investment in well-connected cycling infrastructure, fostering consideration between road users, and adequate legal protection for vulnerable road users. These are the essential elements for providing a cycling environment that encourages participation, with all its health, economic and environmental benefits, while maximising safety.

The impact of compulsory cycle helmet legislation on cyclist head injuries in New South Wales, Australia.

The study aimed to assess the effect of compulsory cycle helmet legislation on cyclist head injuries given the ongoing debate in Australia as to the efficacy of this measure at a population level. We used hospital admissions data from New South Wales, Australia, from a 36 month period centred at the time legislation came into effect. Negative binomial regression of hospital admission counts of head and limb injuries to cyclists were performed to identify differential changes in head and limb injury rates at the time of legislation. Interaction terms were included to allow different trends between injury types and pre- and post-law time periods. To avoid the issue of lack of cyclist exposure data, we assumed equal exposures between head and limb injuries which allowed an arbitrary proxy exposure to be used in the model. As a comparison, analyses were also performed for pedestrian data to identify which of the observed effects were specific to cyclists. In general, the models identified a decreasing trend in injury rates prior to legislation, an increasing trend thereafter and a drop in rates at the time legislation was enacted, all of which were thought to represent background effects in transport safety. Head injury rates decreased significantly more than limb injury rates at the time of legislation among cyclists but not among pedestrians. This additional benefit was attributed to compulsory helmet legislation. Despite numerous data limitations, we identified evidence of a positive effect of compulsory cycle helmet legislation on cyclist head injuries at a population level such that repealing the law cannot be justified.

Can near real-time monitoring of emergency department diagnoses facilitate early response to sporadic meningococcal infection?--prospective and retrospective evaluations.

BACKGROUND: Meningococcal infection causes severe, rapidly progressing illness and reporting of cases is mandatory in New South Wales (NSW), Australia. The NSW Department of Health operates near real-time Emergency Department (ED) surveillance that includes capture and statistical analysis of clinical preliminary diagnoses. The system can provide alerts in response to specific diagnoses entered in the ED computer system. This study assessed whether once daily reporting of clinical diagnoses of meningococcal infection using the ED surveillance system provides an opportunity for timelier public health response for this disease. METHODS: The study involved a prospective and retrospective component. First, reporting of ED diagnoses of meningococcal infection from the ED surveillance system prospectively operated in parallel with conventional surveillance which requires direct telephone reporting of this scheduled medical condition to local public health authorities by hospitals and laboratories when a meningococcal infection diagnosis is made. Follow-up of the ED diagnoses determined whether meningococcal infection was confirmed, and the time difference between ED surveillance report and notification by conventional means. Second, cases of meningococcal infection reported by conventional surveillance during 2004 were retrospectively matched to ED visits to determine the sensitivity and positive predictive value (PPV) of ED surveillance. RESULTS: During the prospective evaluation, 31 patients were diagnosed with meningococcal infection in participating EDs. Of these, 12 had confirmed meningococcal disease, resulting in a PPV of 38.7%. All confirmed cases were notified earlier to public health authorities by conventional reporting.Of 149 cases of notified meningococcal disease identified retrospectively, 130 were linked to an ED visit. The sensitivity and PPV of the ED diagnosis for meningococcal infection was 36.2% and 36.7%, respectively. CONCLUSIONS: Based on prospective evaluation, it is reassuring that existing mechanisms for reporting meningococcal infection perform well and are timely. The retrospective evaluation found low sensitivity and PPV of ED diagnoses for meningococcal disease. Even if more rapid forwarding of ED meningococcal diagnoses to public health authorities were possible, the low sensitivity and PPV do not justify this. In this study, use of an ED surveillance system to augment conventional surveillance of this scheduled medical condition did not demonstrate a benefit.

Reflections on public health surveillance of pandemic (H1N1) 2009 influenza in NSW.

Surveillance has a fundamental role during public health emergencies to provide accurate and relevant information to guide decision making. For each phase of the NSW response to the pandemic H1N1 (2009) influenza there were significant differences in the public health surveillance objectives and response mechanisms. Consequently each phase placed a different emphasis on the various sources and types of surveillance information which were collected and reported upon. We examine whether the NSW public health surveillance systems were able to inform effective public health management throughout all phases of the pandemic (H1N1) 2009 influenza.

Evaluation of alternative respiratory syndromes for specific syndromic surveillance of influenza and respiratory syncytial virus: a time series analysis.

BACKGROUND: Syndromic surveillance is increasingly being evaluated for its potential for early warning of increased disease activity in the population. However, interpretation is hampered by the difficulty of attributing a causative pathogen. We described the temporal relationship between laboratory counts of influenza and respiratory syncytial virus (RSV) detection and alternative groupings of Emergency Department (ED) respiratory diagnoses. METHODS: ED and laboratory data were obtained for the south-eastern area of Sydney, NSW for the period 1 June 2001 - 1 December 2006. Counts of ED visits and laboratory confirmed positive RSV and influenza cases were aggregated by week. Semi-parametric generalized additive models (GAM) were used to determine the association between the incidence of RSV and influenza and the incidence of respiratory syndrome ED presentations while controlling for temporal confounders. RESULTS: For every additional RSV laboratory count, ED diagnoses of bronchiolitis increased by 3.1% (95%CI: 2.7%-3.5%) in the same week. For every additional influenza laboratory count, ED diagnoses of influenza-like illness increased by 4.7% (95%CI: 4.2%-5.2%) one week earlier. CONCLUSION: In this study, large increases in ED diagnoses of bronchiolitis and influenza-like illness were independent and proxy indicators for RSV and influenza activity, respectively.

A multidimensional classification of public health activity in Australia.

BACKGROUND: At present, we have very limited ability to compare public health activity across jurisdictions and countries, or even to ascertain differences in what is considered to be a public health activity. Existing standardised health classifications do not capture important dimensions of public health, which include its functions, the methods and interventions used to achieve these, the health issues and determinants of health that public health activities address, the resources and infrastructure they use, and the settings in which they occur. A classification that describes these dimensions will promote consistency in collecting and reporting information about public health programs, expenditure, workforce and performance. This paper describes the development of an initial version of such a classification. METHODS: We used open-source Protégé software and published procedures to construct an ontology of public health, which forms the basis of the classification. We reviewed existing definitions of public health, descriptions of public health functions and classifications to develop the scope, domain, and multidimensional class structure of the ontology. These were then refined through a series of consultations with public health experts from across Australia, culminating in an initial classification framework. RESULTS: The public health classification consists of six top-level classes: public health 'Functions'; 'Health Issues'; 'Determinants of Health'; 'Settings'; 'Methods' of intervention; and 'Resources and Infrastructure'. Existing classifications (such as the international classifications of diseases, disability and functioning and external causes of injuries) can be used to further classify large parts of the classes 'Health Issues', 'Settings' and 'Resources and Infrastructure', while new subclass structures are proposed for the classes of public health 'Functions', 'Determinants of Health' and 'Interventions'. CONCLUSION: The public health classification captures the important dimensions of public health activity. It will facilitate the organisation of information so that it can be used to address questions relating to any of these dimensions, either singly or in combination. The authors encourage readers to use the classification, and to suggest improvements.

Potential for early warning of viral influenza activity in the community by monitoring clinical diagnoses of influenza in hospital emergency departments.

BACKGROUND: Although syndromic surveillance systems are gaining acceptance as useful tools in public health, doubts remain about whether the anticipated early warning benefits exist. Many assessments of this question do not adequately account for the confounding effects of autocorrelation and trend when comparing surveillance time series and few compare the syndromic data stream against a continuous laboratory-based standard. We used time series methods to assess whether monitoring of daily counts of Emergency Department (ED) visits assigned a clinical diagnosis of influenza could offer earlier warning of increased incidence of viral influenza in the population compared with surveillance of daily counts of positive influenza test results from laboratories. METHODS: For the five-year period 2001 to 2005, time series were assembled of ED visits assigned a provisional ED diagnosis of influenza and of laboratory-confirmed influenza cases in New South Wales (NSW), Australia. Poisson regression models were fitted to both time series to minimise the confounding effects of trend and autocorrelation and to control for other calendar influences. To assess the relative timeliness of the two series, cross-correlation analysis was performed on the model residuals. Modelling and cross-correlation analysis were repeated for each individual year. RESULTS: Using the full five-year time series, short-term changes in the ED time series were estimated to precede changes in the laboratory series by three days. For individual years, the estimate was between three and 18 days. The time advantage estimated for the individual years 2003-2005 was consistently between three and four days. CONCLUSION: Monitoring time series of ED visits clinically diagnosed with influenza could potentially provide three days early warning compared with surveillance of laboratory-confirmed influenza. When current laboratory processing and reporting delays are taken into account this time advantage is even greater.

Planning for pandemic influenza surveillance in NSW.

Early detection of a novel strain (genotype) of influenza virus in the NSW population is the key to controlling a pandemic. If this occurs, ongoing surveillance will help determine the epidemiology and risk factors of the virus as well as its impact on essential services. Important components of surveillance preparedness in NSW include: border surveillance; hospital-based screening for suspected cases; protocols for efficient transport and testing of viral specimens; flexible, robust electronic tools for rapid surveillance data collection; management and reporting; and creation of surveillance surge capacity.

An automated, broad-based, near real-time public health surveillance system using presentations to hospital Emergency Departments in New South Wales, Australia.

BACKGROUND: In a climate of concern over bioterrorism threats and emergent diseases, public health authorities are trialling more timely surveillance systems. The 2003 Rugby World Cup (RWC) provided an opportunity to test the viability of a near real-time syndromic surveillance system in metropolitan Sydney, Australia. We describe the development and early results of this largely automated system that used data routinely collected in Emergency Departments (EDs). METHODS: Twelve of 49 EDs in the Sydney metropolitan area automatically transmitted surveillance data from their existing information systems to a central database in near real-time. Information captured for each ED visit included patient demographic details, presenting problem and nursing assessment entered as free-text at triage time, physician-assigned provisional diagnosis codes, and status at departure from the ED. Both diagnoses from the EDs and triage text were used to assign syndrome categories. The text information was automatically classified into one or more of 26 syndrome categories using automated "naïve Bayes" text categorisation techniques. Automated processes were used to analyse both diagnosis and free text-based syndrome data and to produce web-based statistical summaries for daily review. An adjusted cumulative sum (cusum) was used to assess the statistical significance of trends. RESULTS: During the RWC the system did not identify any major public health threats associated with the tournament, mass gatherings or the influx of visitors. This was consistent with evidence from other sources, although two known outbreaks were already in progress before the tournament. Limited baseline in early monitoring prevented the system from automatically identifying these ongoing outbreaks. Data capture was invisible to clinical staff in EDs and did not add to their workload. CONCLUSION: We have demonstrated the feasibility and potential utility of syndromic surveillance using routinely collected data from ED information systems. Key features of our system are its nil impact on clinical staff, and its use of statistical methods to assign syndrome categories based on clinical free text information. The system is ongoing, and has expanded to cover 30 EDs. Results of formal evaluations of both the technical efficiency and the public health impacts of the system will be described subsequently.