Abstract

Background
Acute respiratory infections are a common reason for consultation with primary and emergency healthcare services. Identifying individuals with a bacterial infection is crucial to ensure appropriate treatment. However, it is also important to avoid over-prescription of antibiotics, to prevent unnecessary side effects and antimicrobial resistance.
We conducted a systematic review to summarize evidence on the diagnostic accuracy of symptoms, signs and point-of-care tests (POCTs) to diagnose bacterial respiratory tract infection in adults, and to diagnose two common respiratory viruses, influenza and respiratory syncytial virus (RSV).

Methods
The primary approach was an overview of existing systematic reviews. We conducted literature searches (22/5/2023) to identify systematic reviews of the diagnostic accuracy of POCTs. Where multiple reviews were identified, we selected the most recent and comprehensive review, with the greatest overlap in scope with our review question. Methodological quality was assessed using the ROBIS tool. Summary estimates of diagnostic accuracy (sensitivity, specificity or area under the curve) were extracted.
Where no systematic review was identified, we searched for primary studies. We extracted sufficient data to construct a 2x2 table of diagnostic accuracy, to calculate sensitivity and specificity. Methodological quality was assessed using the QUADAS-2 tool. Where possible, meta-analyses were conducted. We used GRADE to assess the certainty of the evidence from existing reviews and new analyses.

Results
We identified 23 reviews which addressed our review question; six were selected as the most comprehensive and similar in scope to our review protocol. These systematic reviews considered the following tests for bacterial respiratory infection: individual symptoms and signs, combinations of symptoms and signs (in clinical prediction models), clinical prediction models incorporating C-reactive protein (CRP), and biological markers related to infection (including CRP, procalcitonin, and others). We also identified systematic reviews that reported the accuracy of specific tests for influenza and RSV. No reviews were found that assessed the diagnostic accuracy of white cell count for bacterial respiratory infection, or multiplex tests for influenza and RSV. We therefore conducted searches for primary studies, and carried out meta-analyses for these index tests.
Overall, we found that symptoms and signs have poor diagnostic accuracy for bacterial respiratory infection (sensitivity ranging from 9.6 - 89.1%; specificity ranging from 13.4 - 95%). Accuracy of biomarkers was slightly better, particularly when combinations of biomarkers were used (sensitivity 80% - 90%, specificity 82 - 93%). The sensitivity and specificity for influenza or RSV varied considerably across the different types of tests. Tests involving nucleic acid amplification techniques (either single pathogen or multiplex tests) had the highest diagnostic accuracy for influenza (sensitivity 91 - 99.8%, specificity 96.8 - 99.4%).

Limitations
Most of the evidence was considered low- or very low-certainty when assessed with GRADE, due to imprecision in effect estimates, the potential for bias, and the inclusion of participants outside the scope of this review (children, or people in hospital).

Future work
Currently evidence is insufficient to support routine use of POCTs in primary and emergency care. Further work must establish whether the introduction of POCTs adds value, or simply increases healthcare costs.
Original languageEnglish
Number of pages124
JournalNIHR Health Technology Assessment
Publication statusAccepted/In press - 6 Feb 2024

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