Outcomes of point-of-care testing for influenza in the emergency department of a tertiary referral hospital in Ireland

Background: Seasonal influenza causes significant morbidity and mortality, and represents a recurring financial burden for community- and hospital-based treatment. Nosocomial outbreaks exacerbate the impact of influenza. Rapid diagnosis of influenza has been shown to reduce transmission. However, point-of-care testing (POCT) in emergency departments and prudent direction of patients with the virus to reduce hospital-acquired infection (HAI) have not been evaluated widely.

Aim: To assess performance characteristics of the Abbott ID NOW™ Influenza A & B 2 system, impact on incidence of hospital-acquired influenza, and admission rate ratio for patients who have POCT compared with laboratory testing. POCT was introduced in the 2018-2019 influenza season. Data from then were compared with preceding and subsequent seasons.

Methods: Records of POCT and laboratory testing for the 2017-2018, 2018-2019, and 2019-2020 influenza seasons were analysed. Sensitivity and specificity of POCT were compared pairwise with Xpert Flu A/B/RSV. Patient admission rates and time of waiting for admission were compared.

Findings: Compared to laboratory assay, POCT demonstrated sensitivity of 90.6% (95% confidence interval (CI): 78.6-96.5) and specificity of 99.2% (95.2-100) for influenza A, with 51.4% and 41.9% reductions in numbers of HAIs observed in the two seasons when POCT was available, respectively. The admission rate ratio for influenza cases diagnosed by POCT compared with laboratory diagnosis was 0.72 (95% CI: 0.53-0.97; P = 0.031).

Conclusion: POCT for influenza appears a feasible strategy for testing of patients during peak influenza virus season, with potential to reduce HAI. The relatively rapid turnaround time may also benefit clinical management of patients presenting at emergency departments with suspected influenza.