DIAGNOS TICS


Rapid detection POCTs for rapid detection of infection are applicable across the breadth of healthcare provision. Screening for infection using POCTs in community settings, such as pharmacies or care homes, may provide diagnostic support and reassurance for those patients in which the infection is likely to be self-limiting, with symptoms that can be managed at home, who do not require a healthcare appointment.6,7 In primary care, POC testing can support


clinical decision making in one of three ways: by screening for infection (a rule in/ rule out scenario), informing the need for referral to secondary care, and monitoring disease progression.8 Other areas of healthcare where POCT


for rapid detection of infection could provide additional benefit to existing clinical practice include on the way to hospital via ambulance,9


during ‘digital’ consultations,10


or when targeting hard-to-reach groups.11 Inevitably, some patients will require


assessment and management within the hospital setting. Use of POCTs in the emergency department or acute assessment unit has been shown to offer a rapid triage solution for respiratory tract infections.12,13 Once admitted to hospital, POCTs are available to aid infection prevention decisions in order to prevent transmission of pathogens associated with healthcare-associated infections, such as influenza,14


methicillin-


resistant Staphylococcus aureus (MRSA), Clostridioides difficile, or norovirus.15 POC testing for rapid detection of


infection offers benefits in the following areas: l Patient triage according to severity of illness and urgency to be seen


l Improving patient workflow and reducing backlog


l Appropriate use of limited resources, including laboratory resource


l Informing and improving antimicrobial prescribing and reducing selective pressure


for the development of antimicrobial resistance.


POCT selection Currently, there are >300 commercially available SARS-CoV-2 antigen lateral flow assays.16


With this many tests available, how


is a healthcare provider to choose the test that offers the best performance, value for money, robust supply chain etc? One valuable source of information is


the relevant Target Product Profile (TPP). A TPP outlines an extensive list of desired characteristics and minimum acceptable criteria of a target product, in this instance a diagnostic test, ranging from intended use to performance characteristics.17 In the UK, the Department of Health and


Social Care (DHSC) sought to address the increasingly large number of commercial lateral flow antigen devices available on the market by commissioning a time- limited SARS-CoV-2 test development and evaluation programme, that comprised three phases of testing:18 l Phase 1: a desk-top review, including of manufacturers’ claimed performance and instructions for use,


l Phase 2: controlled laboratory testing indicating the robustness, specificity, sensitivity, and other desired characteristics of the tests,


l Phase 3: testing of a larger sample set (at least 1,000 true negatives and 200 true positives, plus samples from PCR- confirmed positive cases identified by the Lighthouse Laboratories).


Since its establishment in August 2020, the programme has evaluated over 140 lateral flow devices: approximately 30% of the tests met the standards for Phase 2 and 43 tests passed Phase 3a testing.19 According to new regulations, The


Medical Devices (Coronavirus Test Device Approvals) (Amendment) Regulations 2021, it is now a legal requirement for all antigen


Fig.3 A lateral flow antigen


test (Fortress Diagnostics Coronavirus


Antigen Rapid Test)


and molecular COVID-19 detection in vitro diagnostic devices intended for sale in the UK to pass UK government validation. All COVID-19 detection tests available for purchase on the UK market must meet a minimum performance standard, currently assessed by desk-top review, followed by a proposed laboratory validation. As the results of all tests that pass


the desktop review requirements will be published, it is expected that this process will provide stakeholders with the necessary information to make an informed decision when choosing a test.20 Currently, this validation process is


only required for SARS-CoV-2 antigen and molecular tests; however, the Royal Statistical Society Diagnostic Tests Working Group recognised “the inadequate state of current processes for evaluating and regulating medical tests”. Their comprehensive report makes recommendations covering aspects of study design, regulation and transparency, providing a framework for how diagnostic tests need to be evaluated to generate robust evidence that decision makers can trust.21


Importance of data Unlike the evaluation of new therapeutic drugs and other clinical interventions, which are the subject of large randomised controlled trials, diagnostic tests are rarely evaluated in the same robust way. Often diagnostic accuracy studies do not include a pre-defined hypothesis and sample size calculations are omitted. In order to improve the quality of diagnostic accuracy study design and subsequent interpretation of results, minimum acceptable criteria need to be defined.22 As a consequence of the lack of


standardised methodology for evaluation, systematic reviews of POCT for rapid detection of infection are frequently limited to a small number of studies eligible for inclusion.5


Heterogeneity in the clinical Fig. 2 An analyser-based point-of-care test (Aidian QuikRead go CRP) DECEMBER 2021


syndromes assessed (i.e., respiratory tract infection is a broad clinical syndrome) and study design makes drawing strong conclusions difficult. Without this robust level of low risk of bias, high quality evidence, it is difficult to make evidence-


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