Clinical and longitudinal patterns of frequent presenters to emergency departments: A multi-centre data linkage analysis.

OBJECTIVE: To describe clinical characteristics and longitudinal patterns of representation in a cohort of patients who frequently present to EDs for care. METHODS: A retrospective data analysis linking routinely collected ED data across three hospitals. The study population consisted of patients who presented to any ED on 10 or more occasions in any continuous 365-day period from 1 July 2015 to 30 June 2021. Presenting complaints were divided into those with any mental health, drug and alcohol, or social presentations (MHDAS group) and those without (non-MHDAS group). Outcomes of interest were number of presentations as well as temporal and facility clustering of presentations. A per patient regression analysis was performed to identify independent risk factors for increased presentations. RESULTS: Presentations by 1640 frequent ED presenters in the study constituted 4.6% of total ED presentations. MHDAS study group were younger, predominantly English speaking, twice as likely to be married, had lower hospital admission rates and almost three times as many of them did not wait for treatment. Statistically significant differences were also found between these groups regarding presentation clustering, facility entropy, each of the four categories of the number of ED presentations, and Index of Relative Socio-Economic Advantage and Disadvantage. CONCLUSION: Representations associated with MHDAS have a different trajectory of representation episodes compared to non-MHDAS group. Escalating number of presentations and clustering are important predictors of future representation numbers. Those 'did not waits' who appear to be representing would be the highest risk of ongoing and persistent representations in the future and should be the target of early interventions to ensure they are accessing appropriate care before this happens.

Understanding low acuity emergency department presentations in infancy: A cohort study.

OBJECTIVE: Low acuity presentations (LAPs) contribute to large numbers of ED presentations and carry numerous consequences. The present study sought to improve the understanding of regional infant LAPs by analysing temporal patterns of presentation, discharge diagnoses and potential predictive factors. METHODS: This retrospective observational study examined ED presentations among children less than 12 months old (infants) to the Royal Prince Alfred Hospital between 2017 and 2019. Descriptive statistics were used to identify temporal patterns of presentation and common discharge diagnoses among LAPs. Multivariable logistic regression was used to determine the association between early life, demographic and perinatal factors and low acuity presenters. RESULTS: Of 6881 infant ED presentations, 19.8% were LAPs, occurring disproportionately on weekdays (82.2%) and during hours of 08.00-17.00 (69.9%). Respiratory tract infections and gastrointestinal complaints were most common overall, though non-allergic rash, feeding difficulties, eczema and developmental concerns contributed substantially among LAPs. Socio-economic status (SES) (odds ratio [OR] 1.71), overseas maternal nationality (OR 1.25) and Medicare ineligible maternal financial class (OR 0.49) were associated with low acuity presenters. Low appearance, pulse, grimace, activity and respiration score (OR 3.53), low SES (OR 3.26), complicated delivery (OR 1.64), maternal multiparity (OR 0.50), maternal partner presence (OR 0.40) and obstetric complications (OR 0.37) were associated with repeat, multi-low acuity presenters (multi-LAPs). CONCLUSION: A substantial minority of infant ED presentations are LAPs. Targeted interventions may benefit from focusing on families with a background of socioeconomic disadvantage, social isolation, cultural and linguistic diversity and perinatal complications, with a view to strengthening engagement with community-based services among these groups.

24 hours - Life in the E.R.: A state-wide data linkage analysis of in-patients with prolonged emergency department length of stay in New South Wales, Australia.

OBJECTIVE: Describe the characteristics and predictors of mortality for patients who spend more than 24 h in the ED waiting for an in-patient bed and compare baseline clinical and demographic characteristics between tertiary and non-tertiary hospitals. METHODS: This was a state-wide analysis data linkage analysis of adult (age >16 years) ED presentations across New South Wales from 2019 to 2020. Cases were included if their mode of separation from ED indicated admission to an in-patient unit including critical care ward and their ED length of stay was greater than or equal to 24 h. Cases were categorised by service-related groups based on principle diagnosis. RESULTS: A total of 26 854 eligible cases were identified. The most common diagnosis groups were psychiatry, cardiology and respiratory. The odds ratio (OR) for 30-day all-cause mortality in admitted patients with an ED length of stay greater than 24 h were highest in those aged >75 years (OR 15.18, 95% confidence interval [CI] 9.99-23.07, P < 0.001), oncology (OR 10.45, 95% CI 7.93-13.77, P < 0.001) and haematology patients (OR 2.95, 95% CI 2.01-4.33, P < 0.001). CONCLUSION: Interventions and models of care to address ED access block need to focus on mental health patients, older patients particularly those with cardiorespiratory illness and oncology and haematology patients for whom risk of mortality is disproportionately higher.

Clinical characteristics and predictors for hospitalisation during the initial phases of the Delta variant COVID-19 outbreak in Sydney, Australia.

OBJECTIVES: The COVID-19 Delta variant of concern continues to pose significant challenges to health systems globally, with increased transmissibility and different patient populations affected. In Sydney, a virtual model of care was implemented in response to the COVID-19 pandemic and Special Health Accommodation (SHA) was made available for community patients with COVID-19 who could not isolate at home or needed health support. METHODS: This retrospective observational cohort study of all patients with COVID-19 Delta variant in SHA during the initial phases of the Delta variant outbreak in Sydney describes the demographic and clinical characteristics of patients with Delta variant COVID-19 and determines predictors of need for in-patient hospital admission. RESULTS: Data from 794 patients were analysed. One hundred and fifty-seven patients (19.8%) were transferred to ED. Of those, 125 were admitted to an in-patient unit (admission rate from ED 79.6%), and of these 30 (24%) went to ICU and seven were intubated. Two patients died within the follow-up period. Age >40 years, obesity, and presence of fever (temperature >37.5°C), hypoxia (oxygen saturation <95%), tachycardia or gastrointestinal symptoms on initial assessment in SHA were independent predictors of in-patient admission with an AUROC of 0.78 (95% confidence interval 0.73, 0.82). CONCLUSIONS: Initial symptoms and vital signs were just as predictive for short-term deterioration as age and pre-existing comorbidities and should be included in future risk prediction models for COVID-19. Based on this, we derive a proposed risk prediction score that incorporates these predictors with further validation required.

Emergency clinician perceptions of patients who present frequently to the emergency department: a snapshot of current practice.

Objective This study aimed to assess emergency clinician perceptions of adult patients who present frequently to the emergency department (ED) in an Australian context and understand current practices. Methods ED clinicians including general practitioners, career medical officers and nurse unit managers working at New South Wales Australia level 3-6 hospitals were surveyed. Responses to open-ended questions were independently coded by two reviewers and the main themes were analysed. Results Almost all the 210 participants (99%) could identify a population of frequent ED presenters at their hospital. Participants suggested that 9-12 presentations per year was a useful benchmark to use to characterise frequent ED presentations. They also indicated the need to consider as criteria recurrent presentations, their complexity, disease category and timeframe. Participants believed that the cause for presentation, from a restricted list of clinical alternatives, was multifactorial but the single most common cause for presentation was thought to be mental health followed by drug and alcohol. A total of 73% of participants reported that their hospitals had interventions to address frequent ED presentations, most commonly case management, multidisciplinary meetings and staff specialist involvement. Lack of co-ordination between services and a lack of resources in ED were cited as barriers to improving outcomes for patients who frequently present. Conclusions ED clinicians surveyed offered suggestions on how to characterise frequent ED presentations beyond the number of visits to better identify this higher risk population. Additional services, as well as better coordination between patients, families, hospitals and outpatient services, appear needed in order to improve outcomes for this cohort of patients. Interventions should focus on increasing health outcomes, rather than a decrease in the number of presentations alone.

Evaluating Stroke Code Activation Pathway in Emergency Departments study.

OBJECTIVES: To describe the clinical characteristics and outcomes of Code Stroke activations in an ED and determine predictors of a final diagnosis of stroke or transient ischemic attack (TIA) diagnosis. METHODS: This was a retrospective analysis of Code Stroke activations through an ED over 2 years at a quaternary stroke referral centre. Stroke Registry data was used to identify cases with clinical information abstracted from electronic medical records. The primary outcome was a final diagnosis of acute stroke or TIA and the secondary outcome was access to reperfusion therapies (thrombolysis and or endovascular clot retrieval). RESULTS: The study analysed data from 1354 Code Stroke patients in ED. Of all Code Strokes, 51% had a stroke or TIA diagnosis on discharge. Patient characteristics independently associated with increased risk of stroke were increasing age, pre-arrival notification by ambulance, elevated BP or presence of weakness or speech impairment as the initial presenting symptoms. Dizziness/vertigo/vestibular neuritis were the most common alternative diagnoses. One hundred and thirty-five patients (10%) underwent reperfusion therapy. Pre-arrival notification by ambulance was associated with higher proportion of eventual stroke/TIA diagnosis (68% vs 46%, P < 0.001) and significantly lower door to CT and door to needle times for patients undergoing thrombolysis. CONCLUSIONS: In a cohort of patients requiring Code Stroke activation in an ED, increased age, systolic blood pressure and weakness and speech impairment increased the risk of stroke. Prehospital notification was associated with lower door to needle times for patients undergoing thrombolysis.

Emergency department presentations and 30-day mortality in patients from residential aged care facilities.

Objective To describe patterns of emergency department (ED) presentations and predictors of 30-day mortality in patients referred from a residential aged care facility (RACF). Methods A retrospective analysis of linked state-wide emergency, inpatient and death data from 136 public ED hospitals in New South Wales, Australia. Data were collected from the NSW Emergency Department Data Collection database, the NSW Admitted Patient Data Collection database and the NSW Registry of Births, Deaths and Marriages. All patients aged ≥65 years presenting to the ED from a RACF between January 2017 and July 2018 were included. ED diagnosis categories, re-admission rates within 30 days and 30-day all-cause mortality were measured. Results In total, 43 248 presentations were identified. The most common ED diagnosis categories were: injury (26.48%), respiratory conditions (14.12%) and cardiovascular conditions (10.74%). Prolonged ED length of stay was associated with higher adjusted hazard ratios for 30-day all-cause mortality after adjustments for age Charlson Comorbidity Index, triage category and diagnosis category (HR 1.10 95% CI 1.05-1.14 P < 0.001). Conclusions A large proportion of ED presentations from RACFs were for injuries associated with falls and chest infections. There was a range of both high- and low-urgency presentations. Both the 30-day mortality and re-admission rates were high. Predictors of increased mortality included prolonged length of stay in the ED and re-admission within 30 days. The findings are useful in informing discussion around improving access to care in RACFs and coordination of healthcare providers in this cohort.

Capturing vertigo in the emergency room: three tools to double the rate of diagnosis.

OBJECTIVE: Many patients attending the emergency room (ER) with vertigo, leave without a diagnosis. We assessed whether the three tools could improve ER diagnosis of vertigo. METHODS: A prospective observational study was undertaken on 539 patients presenting to ER with vertigo. We used three tools: a structured-history and examination, nystagmus video-oculography (VOG) in all patients, additional video head-impulse testing (vHIT) for acute-vestibular-syndrome (AVS). RESULTS: In the intervention-group (n = 424), case-history classified AVS in 34.9%, episodic spontaneous-vertigo (ESV 32.1%), and episodic positional-vertigo (EPV 22.6%). In AVS, we employed "Quantitative-HINTS plus" (Head-Impulse, Nystagmus and Test-of-Skew quantified by vHIT and VOG, audiometry) to identify vestibular-neuritis (VN) and stroke (41.2 and 31.1%). vHIT gain ≤ 0.72, catch-up saccade amplitude > 1.4○, saccade-frequency > 154%, and unidirectional horizontal-nystagmus, separated stroke from VN with 93.1% sensitivity and 88.5% specificity. In ESV, 66.2 and 14% were diagnosed with vestibular migraine and Meniere's Disease by using history and audiometry. Horizontal-nystagmus velocity was lower in migraine 0.4 ± 1.6○/s than Meniere's 5.7 ± 5.5○/s (p < 0.01). In EPV, benign positional vertigo (BPV) was identified in 82.3% using VOG. Paroxysmal positional-nystagmus lasting < 60 s separated BPV from non-BPV with 90% sensitivity and 100% specificity. In the control group of ER patients undergoing management-as-usual (n = 115), diagnoses included BPV (38.3%) and non-specific vertigo (41.7%). Unblinded assessors reached a final diagnosis in 90.6 and 30.4% of the intervention and control groups. Blinded assessors provided with the data gathered from each group reached a diagnosis in 86.3 and 41.1%. CONCLUSION: Three tools: a structured-assessment, vHIT and VOG doubled the rate of diagnosis in the ER.

Does volume or occupancy influence emergency access block? A multivariate time series analysis from a single emergency department in Sydney, Australia during the COVID-19 pandemic.

OBJECTIVE: The study aims to determine whether ED presentation volume or hospital occupancy had a greater impact on ED performance before and during the COVID-19 health response at a tertiary referral hospital in Sydney, Australia. METHODS: Single centre time series analysis using routinely collected hospital and ED data from January 2019 to September 2020. The primary outcome was ED access block measured by emergency treatment performance (ETP; i.e. percentage of patients who were discharged or transferred to a ward from ED within 4 h of ED arrival time). Secondary outcomes were hospital occupancy, elective theatre cases and ambulance ramping. Multivariate time series analysis was performed using vector autoregression, to model effects of changes in various endogenous and correlated variables on ETP. RESULTS: There was an increase in ETP, drop in ED presentations and decrease in hospital occupancy between April and June 2020. Elective surgery and hospital occupancy had significant effects up to 2 days prior on ETP, while there were no significant effects of either ED or ambulance presentations on ETP. Hospital occupancy itself increased with ED presentations after 2-4 days and decreased with elective surgery after 1 day. Shocks (a one standard deviation increase) in hospital occupancy had a peak impact nearly two times greater compared to ED presentations (-1.43, 95% confidence interval -1.92, -0.93 vs -0.73, 95% confidence interval -1.21, -0.25). CONCLUSION: The main determinants of the reduction of ED overcrowding and access block during the pandemic were associated with reductions in hospital occupancy and elective surgery levels, and more research is required to assess more complex associations beyond the scope of this manuscript.

Incidence and outcomes of aortic dissection for emergency departments in New South Wales, Australia 2017-2018: A data linkage study.

OBJECTIVE: The aims of the present study were to describe the age-specific incidence and 30-day mortality of aortic dissection patients presenting to the EDs in New South Wales (NSW). METHODS: This was a data linkage study involving emergency, inpatient and death registry administrative data from NSW. RESULTS: The present study found 273 instances of aortic dissection in NSW from July 2017 to July 2018. Calculated incidence was 3.47 per 100 000. Incidence increased exponentially with age. The 30-day mortality rate among this cohort was 35.53% (n = 97). Mortality was significantly associated with age and pre-existing comorbidity burden, but was not associated with gender, level of hospital or time of presentation. CONCLUSIONS: The present study found the incidence of aortic dissection within the NSW population to be 3.4 per 100 000. The incidence of aortic dissection in our population increased from 8.6 per 100 000 for people aged between 60 and 80 years to 32 per 100 000 for those aged over 80 years.

Predictors and in-hospital mortality associated with prolonged emergency department length of stay in New South Wales tertiary hospitals from 2017 to 2018.

OBJECTIVE: To determine specific patient, clinical and service factors associated with increased ED length of stay and investigate whether prolonged ED length of stay, as measured by emergency treatment performance (ETP) non-compliance, is an independent predictor of all cause 30-day mortality for patients presenting to, and admitted from ED. METHODS: This was a retrospective analysis of linked state-wide emergency, inpatient and death data from New South Wales. All patients who presented to a tertiary level public hospital (level 5 or 6) ED and admitted to an in-patient unit were included. Outcomes were the proportion of admitted patients who met ETP targets, and 30-day all-cause mortality. RESULTS: A total of 697 600 eligible cases were identified and analysed. The odds of meeting ETP benchmarks were 62% lower in those with complex or multiple medical comorbidities (odds ratio 0.38, 95% confidence interval 0.37-0.40, P < 0.001) compared with patients with no medical comorbidities. Admission under psychiatry, surgical and oncology service-related groups were associated with decreased ETP. The hazard ratio for 30-day all-cause mortality over time was 28% higher in those not meeting ETP benchmarks after adjusting for age, triage category, comorbidities, ICU and service-related group (hazard ratio 1.28, 95% confidence interval 1.26-1.30, P < 0.001). CONCLUSION: Patients with complex and multiple medical comorbidities, and those admitted under certain service-related groups such as psychiatry, surgery and oncology were found to have poorer ETP performance. Overall, failure to meet ETP was associated with increased mortality after adjusting for age, case-mix, comorbidities and acuity.

The Sydney triage to admission risk tool (START) to improve patient flow in an emergency department: a model of care implementation pilot study.

BACKGROUND: The Sydney Triage to Admission Risk Tool (START) is a validated clinical analytics tool designed to estimate the probability of in-patient admission based on Emergency Department triage characteristics. METHODS: This was a single centre pilot implementation study using a matched case control sample of patients assessed at ED triage. Patients in the intervention group were identified at triage by the START tool as likely requiring in-patient admission and briefly assessed by an ED Consultant. Bed management were notified of these patients and their likely admitting team based on senior early assessment. Matched controls were identified on the same day of presentation if they were admitted to the same in-patient teams as patients in the intervention group and same START score category. Outcomes were ED length of stay and proportion of patients correctly classified as an in-patient admission by the START tool. RESULTS: One hundred and thirteen patients were assessed using the START-based model of care. When compared with matched control patients, this intervention model of care was associated with a significant reduction in ED length of stay [301 min (IQR 225-397) versus 423 min (IQR 297-587) p < 0.001] and proportion of patients meeting 4 h length of stay thresholds increased from 24 to 45% (p < 0.001). CONCLUSION: In this small pilot implementation study, the START tool, when used in conjunction with senior early assessment was associated with a reduction in ED length of stay. Further controlled studies are now underway to further examine its utility across other ED settings.

Diagnoses, damned diagnoses and statistics: Dealing with disparate diagnostic coding systems within the New South Wales Emergency Department Data Collection.

OBJECTIVES: The aims of the present study were to describe the distribution of Systematised Nomenclature of Medicine - Clinical Terms (SNOMED-CT) codes used in the current New South Wales Emergency Department Data Collection (NSW EDDC) and classify duplicate and redundant terms into clinically meaningful sub-groups for future analyses. METHODS: This was an analysis of ED diagnosis codes using a large state-wide administrative ED dataset between 2015 and 2018. RESULTS: A total of 7.4 million (77%) of ED episode diagnoses were coded with SNOMED-CT. Of those coded with SNOMED-CT, 12 152 unique codes were identified. Around 1000 of the most frequently used codes accounted for 90% of the presentations coded with SNOMED-CT and 5000 codes accounted for 99.8% of these. Around 7000 codes were deemed to be redundant, and duplication in terms exists across all sub-groups. CONCLUSION: The use of SNOMED-CT in the NSW EDDC has resulted in substantial use of non-specific, duplicate and redundant codes, limiting the capacity of the NSW EDDC to be used for effective data analysis.

Outcomes at non-trauma centres within a trauma referral network: A five-year retrospective cohort study from Australia.

OBJECTIVE: Describe major trauma activity and mortality within non-trauma centres within a single trauma referral network in New South Wales, Australia over a five-year period. DESIGN: Multi-centre retrospective cohort study. METHODS: This was a retrospective cohort study of trauma patients presenting to non-trauma centres within a metropolitan major trauma referral network between January 2011 and June 2016. The outcome of interest examined was in-hospital mortality for major trauma (Injury Severity Score ISS>12), consistent with current state-wide trauma reporting guidelines. RESULTS: A total of 4827 trauma patients were identified from non-major trauma centres of which 352 (7.3%) had an ISS>12. The most common mechanisms were road trauma (54.6%) and falls (37.4%). The mortality with those ISS>12 was 9.3%. During the same period, the overall trauma mortality (ISS>12) at the Major Trauma Centre was similar at 10.2% (p=0.10). After adjusting for age and ISS differences between Major Trauma Centre and other facilities within the network, the odds of in-hospital mortality after major trauma (ISS>12) was higher in the Major Trauma Centre compared to other facilities within the same network (adjusted odds ratio 2.7; 95% CI 1.6, 4.7; p=0.0004). CONCLUSION: Across a single trauma referral network coordinated by a major trauma service, non-trauma centres account for around a quarter of total major trauma volume and adjusted mortality was lower in these centres compared to patients treated at major trauma centres.

Extending the Sydney Triage to Admission Risk Tool (START+) to predict discharges and short stay admissions.

OBJECTIVE: This study aims to validate previously reported triage tool titled Sydney Triage to Admission Risk Tool (START+) and investigate whether an extended version of the tool could be used to identify and stream appropriate short stay admissions to ED observation units or specialised short stay inpatient wards. METHODS: This was a prospective study at two metropolitan EDs in Sydney, Australia. Consecutive triage encounters were observed by a trained researcher and START scores calculated. The primary outcome was length of stay <48 hours. Multivariable logistic regression was used to estimate area under curve of receiver operator characteristic (AUROC) for START scores. The original START tool was then extended to include frailty and multiple or major comorbidities as additional variables to assess for further predictive accuracy. RESULTS: There were 894 patients analysed during the study period. Of the 894 patients, there were 732 patients who were either discharged from ED or admitted for <2 days. The AUROC for the original START+ tool was 0.80 (95% CI 0.77 to 0.83). The presence of frailty was found to add a further five points and multiple comorbidities added another four points on top of the START score, and the AUROC for the extended START score 0.84 (95% CI 0.81 to 0.88). CONCLUSION: The overall performance of the extended ED disposition prediction tool that included frailty and multiple medical comorbidities significantly improved the ability of the START tool to identify patients likely to be discharged from ED or require short stay admission <2 days. TRIAL REGISTRATION NUMBER: ACTRN12618000426280.

Presentations to NSW emergency departments with self-harm, suicidal ideation, or intentional poisoning, 2010-2014.

OBJECTIVE: To evaluate population trends in presentations for mental health problems presenting to emergency departments (EDs) in New South Wales during 2010-2014, particularly patients presenting with suicidal ideation, self-harm, or intentional poisoning. DESIGN, SETTING AND PARTICIPANTS: This was a retrospective, descriptive analysis of linked Emergency Department Data Collection registry data for presentations to NSW public hospital EDs over five calendar years, 2010-2014. Patients were included if they had presented to an ED and a mental health-related diagnosis was recorded as the principal diagnosis. MAIN OUTCOME MEASURES: Rates of mental health-related presentations to EDs by age group and calendar year, both overall and for the subgroups of self-harm, suicidal ideation and behaviour, and intentional poisoning presentations. RESULTS: 331 493 mental health-related presentations to 115 NSW EDs during 2010-2014 were analysed. The presentation rate was highest for 15-19-year-old patients (2014: 2167 per 100 000 population), but had grown most rapidly for 10-14-year-old children (13.8% per year). The combined number of presentations for suicidal ideation, self-harm, or intentional poisoning increased in all age groups, other than those aged 0-9 years; the greatest increase was for the 10-19-year-old age group (27% per year). CONCLUSIONS: The rate of mental health presentations to EDs increased significantly in NSW between 2010 and 2014, particularly presentations by adolescents. Urgent action is needed to provide better access to adolescent mental health services in the community and to enhance ED models of mental health care. The underlying drivers of this trend should be investigated to improve mental health care.

The Sydney Triage to Admission Risk Tool (START): A prospective validation study.

OBJECTIVE: The present study aims to prospectively validate the Sydney Triage to Admission Risk Tool (START) to predict ED disposition. METHODS: This was a prospective validation study at two metropolitan EDs in Sydney, Australia. Consecutive triage encounters were observed by a trained researcher and START scores calculated. The primary outcome was patient disposition (discharge or inpatient admission) from the ED. Multivariable logistic regression was used to estimate area under curve of receiver operator characteristic (AUC ROC) for START scores as well as START score in combination with other variables such as frailty, general practitioner referral, overcrowding and major medical comorbidities. RESULTS: There were 894 patients analysed during the study period. The START score when applied to the data had AUC ROC of 0.80 (95% CI 0.77-0.83). The inclusion of other clinical variables identified at triage did not improve the overall performance of the model with an AUC ROC of 0.81 (95% CI 0.78-0.84) in the present study. CONCLUSION: The overall performance of the START tool with respect to model discrimination and accuracy has been prospectively validated. Further clinical trials are required to test the clinical effectiveness of the tool in improving patient flow and overall ED performance.

Influenza-associated delays in patient throughput and premature patient departure in emergency departments in New South Wales, Australia: A time series analysis.

OBJECTIVES: Influenza outbreaks cause overcrowding in EDs. We aimed to quantify the impact of influenza on the National Emergency Access Targets and premature patient departure in New South Wales, Australia. METHODS: This was a retrospective observational study of 11 million presentations to 115 hospitals during 2010-2014, using routinely collected administrative records. A time series generalised additive regression model was used to assess the correlation between weekly influenza activity and the weekly proportion of patients leaving the ED in >4 h and the proportion that departed before commencing or completing treatment ('did not wait'), after controlling for background winter and holiday effects. RESULTS: During 2011-2014, peak annual circulating influenza was associated with the peak weekly proportion of presentations that left in >4 h. The maximum estimated absolute weekly change in that proportion was 3.88 (95% confidence interval 3.02-4.74) percentage points in 2014. For presentations that did not wait, influenza circulation was associated with statistically significant increases in all years, with a maximum weekly value of 2.68 (95% confidence interval 2.31-3.06) percentage points in 2012. CONCLUSIONS: Circulating influenza was associated with sustained increases and peaks in delayed patient throughput and premature patient departures. Influenza surveillance information may assist with development of health system and hospital workforce planning and bed management activities.

Emergency Department demand associated with seasonal influenza, 2010 through 2014, New South Wales, Australia.

INTRODUCTION: Influenza's impact on health and health care is underestimated by influenza diagnoses recorded in health-care databases. We aimed to estimate total and non-admitted influenza-attributable hospital Emergency Department (ED) demand in New South Wales (NSW), Australia. METHODS: We used generalized additive time series models to estimate the association between weekly counts of laboratory-confirmed influenza infections and weekly rates of total and non-admitted respiratory, infection, cardiovascular and all-cause ED visits in NSW, Australia for the period 2010 through 2014. Visit categories were based on the coded ED diagnosis or the free-text presenting problem if no diagnosis was recorded. RESULTS: The estimated all-age, annual influenza-attributable respiratory, infection, cardiovascular and all-cause visit rates/100 000 population/year were, respectively, 120.6 (99.9% confidence interval [CI] 102.3 to 138.8), 79.7 (99.9% CI: 70.6 to 88.9), 14.0 (99.9% CI: 6.8 to 21.3) and 309.0 (99.9% CI: 208.0 to 410.1). Among respiratory visits, influenza-attributable rates were highest among < 5-year-olds and ≥ 85-year-olds. For infection and all-cause visits, rates were highest among children; cardiovascular rates did not vary significantly by age. Annual rates varied substantially by year and age group, and statistically significant associations were absent in several years or age groups. Of the respiratory visits, 73.4% did not require admission. The non-admitted proportion was higher for the other clinical categories. Around 1 in 100 total visits and more than 1 in 10 respiratory or infection visits were associated with influenza. DISCUSSION: Influenza is associated with a substantial and annually varying burden of hospital-attended illness in NSW.