Emergency Department demand associated with seasonal influenza, 2010 through 2014, New South Wales, Australia
DOI:
https://doi.org/10.5365/wpsar.2017.8.2.002Abstract
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.
References
Nicholson KG, Wood JM, Zambon MC. Influenza. Lancet 2003;362:1733-45.
Simonsen L, Spreeuwenberg P, Lustig R, et al. Global Mortality Estimates for the 2009 Influenza Pandemic from the GLaMOR Project: A Modeling Study. Plos Medicine 2013;10(11) doi: 10.1371/journal.pmed.1001558
Cheng P-Y, Palekar R, Azziz-Baumgartner E, et al. Burden of influenza-associated deaths in the Americas, 2002–2008. Influenza and Other Respiratory Viruses 2015;9:13-21. doi: 10.1111/irv.12317
Muscatello DJ, Amin J, MacIntyre CR, et al. Inaccurate ascertainment of morbidity and mortality due to influenza in administrative databases: a population-based record linkage study. PLoS One 2014;9(5):e98446. doi: 10.1371/journal.pone.0098446
Muscatello DJ, Newall AT, Dwyer DE, et al. Mortality attributable to seasonal and pandemic influenza, Australia, 2003 to 2009, using a novel time series smoothing approach. PLoS ONE 2013;8(6):e64734. doi: 10.1371/journal.pone.0064734
World Health Organization. A Manual for Estimating Disease Burden Associated With Seasonal Influenza Geneva: World Health Organization; 2016. Available from: http://www.who.int/influenza/resources/publications/manual_burden_of_disease/en/ accessed 3 Nov 2016.
Schanzer DL, Schwartz B. Impact of seasonal and pandemic influenza on emergency department visits, 2003-2010, Ontario, Canada. Acad Emerg Med 2013;20(4):388-97. doi: 10.1111/acem.12111 [published Online First: 2013/05/25]
Self W, Griffin M, Zhu Y, et al. The high burden of pneumonia on US emergency departments during the 2009 influenza pandemic. The Journal of infection 2014;68(2):156-64. doi: 10.1016/j.jinf.2013.10.005
Guo RN, Zheng HZ, Ou CQ, et al. Impact of Influenza on Outpatient Visits, Hospitalizations, and Deaths by Using a Time Series Poisson Generalized Additive Model. PLoS One 2016;11(2):e0149468. doi: 10.1371/journal.pone.0149468 [published Online First: 2016/02/20]
Olson DR, Heffernan RT, Paladini M, et al. Monitoring the impact of influenza by age: emergency department fever and respiratory complaint surveillance in New York City. PLoS Med 2007;4(8):e247. doi: 10.1371/journal.pmed.0040247 [published Online First: 2007/08/09]
MacIntyre CR, Mahimbo A, Moa AM, et al. Influenza vaccine as a coronary intervention for prevention of myocardial infarction. Heart 2016
Geoscience Australia. Area of Australia - States and Territories: Australian Government; 2014. Available from: http://www.ga.gov.au/scientific-topics/geographic-information/dimensions/area-of-australia-states-and-territories accessed 15 Apr 2017.
Australian Bureau of Statistics. 3101.0 - Australian Demographic Statistics, Mar 2016. Canberra: Australian Bureau of Statistics; 2016. Available from: http://www.abs.gov.au accessed 3 Nov 2016.
Dinh MM, Berendsen Russell S, Bein KJ, et al. Understanding drivers of Demand for Emergency Service Trends in Years 2010–2014 in New South Wales: An initial overview of the DESTINY project. Emergency Medicine Australasia 2016;28(2):179-86. doi: 10.1111/1742-6723.12542
Communicable Diseases Branch. Influenza (laboratory confirmed) public dataset. Canberra: Australian Department of Health, 2003.
Kelly HA, Grant KA, Tay EL, et al. The significance of increased influenza notifications during spring and summer of 2010–11 in Australia. Influenza and Other Respiratory Viruses 2013;7(6):1136-41. doi: 10.1111/irv.12057
SAS Software [program]. 9.4 version. Cary, NC, USA: SAS Institute Inc, 2012.
New South Wales Health. HealthStats NSW - Influenza and pneumococcal immunisation North Sydney: NSW Health; 2016. Available from: http://www.healthstats.nsw.gov.au/ accessed 15 Apr 2017.
Muscatello DJ, Barr M, Thackway SV, et al. Epidemiology of Influenza-like Illness during Pandemic (H1N1) 2009, New South Wales, Australia. Emerging Infectious Diseases 2011;17(7):1240-47. doi: 10.3201/eid1707.101173
World Health Organization. FluNet Geneva: World Health Organization; 2016. Available from: http://www.who.int/influenza/gisrs_laboratory/flunet/en/ accessed 15 Feb 2017.
Kelly HA, Sullivan SG, Grant KA, et al. Moderate influenza vaccine effectiveness with variable effectiveness by match between circulating and vaccine strains in Australian adults aged 20–64 years, 2007–2011. Influenza and Other Respiratory Viruses 2013;7(5):729-37. doi: 10.1111/irv.12018
Levy A, Sullivan SG, Tempone SS, et al. Influenza vaccine effectiveness estimates for Western Australia during a period of vaccine and virus strain stability, 2010 to 2012. Vaccine 2014;32(47):6312-18. doi: http://dx.doi.org/10.1016/j.vaccine.2014.08.066
Hancock K, Veguilla V, Lu X, et al. Cross-Reactive Antibody Responses to the 2009 Pandemic H1N1 Influenza Virus. New England Journal of Medicine 2009;361(20):1945-52. doi: 10.1056/NEJMoa0906453
Muscatello DJ, Cretikos MA, Macintyre CR. All-cause mortality during first wave of pandemic (H1N1) 2009, New South Wales, Australia, 2009. Emerg Infect Dis 2010;16(9):1396-402. doi: 10.3201/eid1609.091723
Sullivan SG, Carville KS, Chilver M, et al. Pooled influenza vaccine effectiveness estimates for Australia, 2012-2014. Epidemiology and infection 2016;144(11):2317-28. doi: 10.1017/s0950268816000819
New South Wales Health. Annual Report - Annual Report 2014-15 NSW Health North Sydney: NSW Health; 2016. Available from: http://www.health.nsw.gov.au/annualreport/Pages/annualreport15.aspx accessed 15 Apr 2017.
Australian Bureau of Statistics. 4390.0 - Private Hospitals, Australia, 2014-15 [document]. Canberra: Australian Bureau of Statistics; 2016. Available from: http://www.abs.gov.au accessed 15 Apr 2017.
Australian Institute of Health and Welfare. Emergency department care 2014-15: Australian hospital statistics Canberra: Australian Institute of Health and Welfare; 2016. Available from: http://www.aihw.gov.au/publication-detail/?id=60129553619 accessed 3 Nov 2016.
