Rapid flu testing in emergency care

Rapid flu testing in emergency care

The impact of rapid molecular diagnostic testing of respiratory viruses

This project is funded by a National Health and Medical Research Council Partnership Projects Grant APP1111925: 2015-2020.

Project summary

  • In 2017, influenza in Australia caused 1,255 deaths, and this year has started with a bang: 20,000 case of flu have already been reported in 2019, with experts predicting record flu numbers.
  • The conventional flu test can take up to 26 hours to deliver results: The new rapid flu test has been shown to deliver results in just over two hours, potentially resulting in less hospital admissions and fewer hospital resources implicated.
  • Improving the timeliness of diagnosis: When the rapid flu test is used, 70% of patients can be accurately diagnosed while in the emergency department, compared to less than 2% using the conventional test.
  • Delays in influenza testing may lead to misdiagnosis and greater hospital admissions: Macquarie University researchers have provided evidence to support the rapid flu test being implemented into emergency departments nationally.

Project members - Macquarie University

 
Professor
ProfessorDr Nasir Wabe
Research Fellow
 
A/Professor
  

Collaborators:

  • NSW Health Pathology
  • Prince of Wales Hospital

Background and aims

Background

Influenza (commonly called ‘flu’) and other respiratory viruses such as a respiratory syncytial virus (RSV), rhinovirus, coronavirus, human metapneumovirus and parainfluenza viruses cause substantial health and economic burden1,2. The accurate diagnosis of respiratory infections has up to recently depended on a molecular method using multiplex polymerase chain reaction (PCR) panel testing, which have a lengthy turnaround time (TAT), impacting the efficiency of emergency department (ED) workflows and care processes. Delays in laboratory test results contributes to ED overcrowding and prolonged ED length of stay (LOS)3-5. Improving test result availability can potentially improve patient flow in the ED and reduce overcrowding6-8.

Rapid molecular assays for respiratory viruses using a PCR-based technology (rapid PCR hereafter) are now available in hospital-based laboratories. New South Wales (NSW) introduced the use of rapid PCR (Cepheid Xpert® Flu/RSV XC) which can detect influenza A/B and RSV with comparable sensitivity and specificity to traditional PCR tests9. In this study we aimed to determine if the introduction of rapid PCR improved patient and laboratory outcomes compared with the pre-implementation period where the standard multiplex PCR (Seegene AllplexTM RP) has been used.

Aims
Study 1: Molecular Rapid Flu Testing in Emergency Care

To determine whether the use of rapid PCR in EDs was associated with better patient and laboratory outcomes.

Study 2: Molecular Rapid Flu Testing in Hospitals

To determine whether the use of rapid PCR was associated with improved outcomes for adults hospitalised with respiratory illness.

References

  1. Chen Y, Kirk MD. Incidence of acute respiratory infections in Australia. Epidemiology and infection. 2014;142(7):1355-1361.
  2. Shi T, McAllister DA, O'Brien KL, et al. Global, regional, and national disease burden estimates of acute lower respiratory infections due to respiratory syncytial virus in young children in 2015: a systematic review and modelling study. Lancet (London, England). 2017;390(10098):946-958.
  3. Lewandrowski K. POC testing in the emergency department: Strategies to improve clinical and operational outcomes. 2011.
  4. Pines JM, Hilton JA, Weber EJ, et al. International perspectives on emergency department crowding. Academic emergency medicine : official journal of the Society for Academic Emergency Medicine. 2011;18(12):1358-1370.
  5. Li L, Georgiou A, Vecellio E, et al. The effect of laboratory testing on emergency department length of stay: a multihospital longitudinal study applying a cross-classified random-effect modeling approach. Academic emergency medicine : official journal of the Society for Academic Emergency Medicine. 2015;22(1):38-46.
  6. Rooney KD, Schilling UM. Point-of-care testing in the overcrowded emergency department–can it make a difference? Critical Care. 2014;18(6):692.
  7. Rappo U, Schuetz AN, Jenkins SG, et al. Impact of Early Detection of Respiratory Viruses by Multiplex PCR Assay on Clinical Outcomes in Adult Patients. Journal of clinical microbiology. 2016;54(8):2096-2103.
  8. Sullivan C, Staib A, Khanna S, et al. The National Emergency Access Target (NEAT) and the 4-hour rule: time to review the target. The Medical journal of Australia. 2016;204(9):354.
  9. Salez N, Ninove L, Thirion L, et al. Evaluation of the Xpert Flu test and comparison with in-house real-time RT-PCR assays for detection of influenza virus from 2008 to 2011 in Marseille, France. Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases. 2012;18(4):E81-83.

Design and method

Study 1: Molecular Rapid Flu Testing in Emergency Care

Design: A before-and-after study in four metropolitan public hospital EDs in Sydney, NSW. The ‘before’ group were tested by standard PCR during the pre-implementation, July to December 2016 (n=1491), and the ‘after’ group were tested by rapid PCR during the post-implementation, July to December 2017 (n=2250).

Outcome measures: Hospital admissions; ED LOS; TAT; patient receiving test result before leaving the ED; ordering of other common laboratory tests.

Statistical analysis: Logistic regression analyses of binary outcomes (eg, hospital admission: yes/no) and quantile regression analyses of continuous outcomes (eg, ED LOS) were undertaken

Study 2: Molecular Rapid Flu Testing in Hospitals

Design: A controlled quasi-experimental study in three metropolitan public hospitals in Sydney, NSW. Intervention groups received standard PCR during the pre-implementation, July-December 2016, (n=953) and rapid PCR during the post-implementation, July-December 2017, (n=1,209). Control groups (pre-implementation, n=937 and post-implementation, n =1,102) were selected randomly from adults hospitalised with respiratory illness during the same periods.

Outcome measures: The outcomes were hospital LOS and ordering of common microbiology tests (blood culture, urine culture, sputum culture, respiratory bacterial and virus serology).

Statistical analysis: The impact of a rapid PCR on hospital LOS was assessed using a quantile (median) regression. A difference-in-differences (DID) analysis was conducted to estimate the effect of a rapid PCR on the LOS by comparing the median change over time in the LOS for the intervention group, compared to the median change over time for the control group. Logistic regression was used for comparison of microbiology test utilisation between intervention and control groups.

Results

The use of rapid PCR was associated with a non-significant 8.9hrs reduction in median LOS (95% confidence interval [CI], -21.5hrs to 3.7hrs; P=0.17) for all patients and a significant 21.5hrs reduction in median LOS (95% CI, -36.8hrs to -6.2hrs; P<0.01) among patients with positive test results in an adjusted DID analysis. For patients receiving test results before disposition, rapid PCR use was associated with a significant reduction in LOS irrespective of test results. Compared with standard PCR testing, rapid PCR use was significantly associated with fewer blood culture (adjusted odds ratio [aOR], 0.67; 95% CI, 0.5-0.82; P<0.001), sputum culture (aOR, 0.56; 95% CI, 0.47-0.68, P<0.001), bacterial serology (aOR, 0.44; 95% CI, 0.35-0.55, P<0.001) and viral serology (aOR, 0.42; 95% CI, 0.33-0.53, P<0.001) but not urine culture (aOR, 0.94; 95% CI, 0.78-1.12, P=0.48).

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Content owner: Australian Institute of Health Innovation Last updated: 11 Mar 2024 5:12pm

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