Molecular point-of-care testing for respiratory viruses

Abstract

Respiratory virus infection is a common cause of hospitalisation in adults. New molecular platforms have been developed that can be deployed as point-of-care tests (POCT). Use of molecular POCTs for respiratory viruses may improve clinical care. This thesis explores the clinical impact of molecular point-of-care testing for respiratory viruses in adults hospitalised with acute respiratory illness. We did a large pragmatic, open-label, randomised controlled trial of routine molecular POCT for respiratory viruses, compared with routine clinical care, in adults presenting with acute respiratory illness to a large teaching hospital in Southampton over two winter seasons (the ResPOC trial). We recruited 720 patients of which 714 were included in the modified intention-to-treat analysis (360 assigned to POCT and 354 to routine care). The proportion of patients who received antibiotics was 84% in the POCT group compared with 83% in the control group (p=0.84). Of those who received antibiotics, 17% in the POCT group received a single dose or < 48 hours of antibiotics compared with 9% in the control group (p=0.0047). Mean length of stay was shorter in the POCT group (5.7 days) than in the control group (6.8 days; p=0.443). Appropriate antiviral treatment of influenza-positive patients was more common in the POCT group (91%) than in the control group (65%; p=0.0026). We went on to show that POCT with a turnaround time to results of < 1.6 hours was associated with higher rates of early hospital discharge and early discontinuation of antibiotics compared to longer turnaround times. To further explore attitudes to neuraminidase inhibitor use in influenza treatment, an online, cross-sectional questionnaire-based survey of self-reported prescribing practice using clinical scenarios was distributed to frontline clinicians. There were 237 respondents. Adherence to national treatment guidelines in the clinical scenarios ranged from 56% to 72% with considerable variability between specialities. Using ResPOC trial data, I also examined the reliability of pneumonia diagnoses on discharge documentation. 28% of patients with a diagnosis of pneumonia had no radiological evidence of pneumonia. 35% of patients with clinico-radiological evidence of pneumonia did not have a diagnosis of pneumonia recorded. In conclusion, while routine molecular POCT for respiratory viruses did not reduce the proportion of patients treated with antibiotics, POCT led to higher use of single doses or brief courses of antibiotics. POCT was also associated with a reduced length of stay and antiviral use and appeared to be safe. Rapid testing turnaround times were associated with better outcomes and unlikely to be achievable with centralised laboratory testing; this suggests that viral diagnostics should be performed at the point-of-care. The trial data also showed frequent misclassification of pneumonia diagnosis on discharge documentation and this may have clinical, financial and research data implications. A large survey of frontline hospital physicians suggested that guideline adherence in influenza treatment was sub-optimal but strategies that promote rapid diagnostic testing such as molecular POCT may improve adherence.

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Identifiers

ORCID for Nathan Brendish: orcid.org/0000-0002-9589-4937

ORCID for Tristan Clark: orcid.org/0000-0001-6026-5295

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