Elsevier

Journal of Clinical Virology

Volumes 99–100, February–March 2018, Pages 5-9
Journal of Clinical Virology

Diagnostic performances of the Xpert® Flu PCR test and the OSOM® immunochromatographic rapid test for influenza A and B virus among adult patients in the Emergency Department

https://doi.org/10.1016/j.jcv.2017.12.005Get rights and content

Highlights

  • •

    RIDT has a sensitivity and specificity greater than 95% and 98%.

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    These results are close similar for all circulating strains from the last Influenza epidemic season.

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    Our results show the utility of RIDT in adults and the elderly.

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    RIDT can be performed by emergency nurses and physicians.

Abstract

Background

New rapid influenza diagnostic tests (RIDT) are available but their clinical utility in adults has not been validated.

Objectives

To evaluate the diagnostic performances of OSOM® Ultra Flu A&B a RIDT on viral strains of influenza A/B from the last epidemic season, and its feasibility by Emergency Department (ED) physicians and nurses.

Study design

Of the 1099 patients admitted to the ED with suspected influenza, all having a nasopharyngeal swab tested by the Xpert® Flu PCR and then stored at −20 °C; 500 were selected at random and their samples were tested using the RIDT. Two experts reviewed ED and hospital medical records and all virological data to define influenza cases. Intra- and inter-observer variability were calculated.

Results

Of the 500 patients included 45% were ≥75 years, 122 (24.4%) presented with influenza based on clinical and virological criteria. PCR test performances (%) were Se 98.4 (95% CI 93.6–99.7), Spe 99.7 (98.3–100), PPV 99.2 (94.8–100) and NPV 99.5 (97.9–100); and RIDT performances were Se 95.1 (89.2–97.9), Spe 98.4 (96.4–99.4), PPV 95.1 (87.2–99.9) and NPV 98.4 (96.4–98). There was no difference in test performance between influenza A and B virus nor between the influenza A subtypes. Intra- and inter-observer variability of RIDT were 0.94 (0.89–0.99) and 0.96 (0.92–1).

Conclusion

Our results show that the Xpert® Flu PCR and the OSOM® Ultra Flu A&B Test perform very well in diagnosing strains of circulating virus in adults and elderly. Our results also confirm the feasibility of this RIDT at point-of-care by ED staff.

Section snippets

Background

Respiratory viruses are responsible for significant morbidity and mortality in both children and adults [1]. The predictive value of symptoms and clinical signs for the diagnosis of influenza is very low, regardless of the viral strain involved [[2], [3], [4], [5], [6]]. Early implementation of antiviral treatment and isolation measures depend on rapid diagnosis of influenza [[7], [8], [9], [10]]. Moreover, the use of testing for respiratory viruses within the ED in adults was recently

Objectives

The objectives of this study were to estimate the clinical performances of a new commercially available RIDT, which included the antigens of new circulating strains and modified sample collection system, antigen extraction and reading cassette, and that can be performed at point-of-care [18] (OSOM® Ultra Flu A&B Test), and a reference NAAT performed in the virology laboratory (Xpert® Flu PCR test) on clinical samples from the last influenza epidemic season, comparing their results with a

Study population and period

Patients seen in the ED during the 2016–2017 epidemic period and presenting one of the following criteria were included [19]: i) suspected influenza based on clinical criteria (influenza-like syndromes); ii) pneumopathy; iii) presence of signs of severity: polypnoea, cyanosis, oxygen saturation Spa02 <95%, pneumonia, wheeze, tachycardia, hypotension, areas of mottled skin, malaise, change in mental status, oliguria; iv) presence of underlying clinical conditions indicating an increased risk of

Results

During the 2016–2017 epidemic period, 1099 patients were identified with suspected influenza and were tested. Finally, 233 (233/1099 (21.2%)) produced a positive influenza NAAT. Among them, 420 patients were selected at random. Given the low prevalence of influenza B, the 20 cases of influenza B and 60 control cases selected at random from the overall population were included in the study population. The study population comprised 500 patients at that point. The characteristics of the overall

Discussion

Our study in adult emergency patients seen during the 2016–2017 influenza epidemic season revealed excellent diagnostic performances for both the Xpert® Flu PCR and the OSOM® Ultra Flu A&B Test. Similarly, we demonstrated excellent results in the assessing variability in reading the OSOM® Ultra Flu A&B Test performed by ED personnel following a brief training session.

Difficulties in diagnosing influenza within Emergency Departments are linked to the diversity of clinical pictures that can be

Conflicts of interest

None to declare.

Funding

None

Ethical approval

The dataset was completely anonymous and did not contain any identifiable personal health information. The protocol was approved by the Assistance Publique-Hôpitaux de Paris ethics, research and informatics committees.

Authors contributions

SA, NF, AG, HI, PGG, DB, PK, CC, BV and EC conceived the study and designed the trial. SA, NF, AG and EC supervised the conduct of the trial and data collection. SA, NF, AG, HI, PGG, DB, PK, CC, BV and EC undertook recruitment of patients and managed the data, including quality control. SA, NF, AG, BV and EC provided statistical advice on study design and analysed the data. SA, NF, AG and EC drafted the manuscript, and all authors contributed substantially to its revision. EC takes

Acknowledgments

None.

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