Clinical performance and economic evaluations of the Alere™ i Influenza A&B near patient test using throat swabs: a cohort diagnostic accuracy study and cost analysis

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  2. Dr Joy Allen
  3. Rachel O'Leary
  4. Dr David Price
  5. Professor John Simpson
  6. Professor Luke Vale
Author(s)Davis S, Allen J, O'Leary R, Power M, Price DA, Simpson AJ, Tunbridge A, Vale L, Whiteside M, Evans C, Raza M
Publication type Article
JournalJournal of Hospital Infection
IssueePub ahead of Print
ISSN (print)0195-6701
ISSN (electronic)1532-2939
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BackgroundClinical diagnostic sensitivity alone is inadequate in the diagnosis of influenza. PCR testing is sensitive however the inherent delays in result availability potentially prolong time to isolation and treatment. Until recently no near patient test (NPT) has demonstrated adequate sensitivity for routine clinical use.AimTo evaluate diagnostic accuracy; time to result availability; clinical impact and cost consequences of Alere™ i Influenza A&B NPT (Alere Inc., Waltham, MA, USA) using off-label throat swabs.MethodsProspective, multi-centre (4 UK NHS hospitals), diagnostic accuracy cohort study with cost modelling. Throat swab samples from suspected influenza patients were tested for influenza using the reference standard of PCR; a second throat swab was tested using NPT.Findings827 participants recruited; 589 suitable for analysis: Sensitivity 75.8% (95% CI 67.0-84.6%); specificity 96.8% (95% CI 95.2-98.3%). Sensitivity varied between Sheffield (NGH 82.1%; RHH 83.3%) and other sites (DRI 71.4%; RVI 50.0%) while specificity was high (92% - 100%). PPV was 81.2% (95% CI 72.9- 89.5%) with NPV 95.6% (95% CI 93.9-97.4%) with observed prevalence of 15.4%. Median time to result for PCR was 1.1 days (on-site laboratories) and 5.2 days (remote laboratories). Isolation findings: 75% influenza positive not isolated; 69% isolated participants did not have influenza. For a cohort of 1000 participants, annual estimated non-diagnostic cost savings with NPT are £215, 040.ConclusionsThis first prospective study of the Alere™ i NPT using throat swabs demonstrates high specificity, high PPV during seasonal epidemics, and rapid result availability which could lead to substantial cost savings.
PublisherW.B. Saunders Co. Ltd.
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