Rapid molecular tests for viral pathogen detection provide accurate results and their implementation in hospital settings is recommended, according to review results published in Clinical Infectious Diseases.

Acute respiratory tract infections are the third leading cause of death worldwide. Accounting for 50% to 60% of microbiologic etiologies, respiratory viruses predominate as causative pathogens in patients who are hospitalized with acute respiratory tract infections. Rapid identification of viral etiologies can improve effective patient management by influencing several factors, including decision making regarding antibiotic treatment and implementation of infection-control measures to prevent further transmission.

There has been a transition over the last decade from conventional techniques (viral cultures and immunoassays) to real-time polymerase chain reaction techniques, which can still take up to 48 hours. However, there is now increased access to rapid diagnostics with turnaround times of <1 hour, although whether these rapid methods improve patient outcomes is still being debated. Therefore, this review systemically summarized the quality and meta-analysis results of diagnostic test accuracy studies and reviewed studies evaluating the clinical impact of rapid molecular testing for respiratory viruses (Prospero‑database identifier, CRD42017057881).

A total of 63 separate reports from EMBASE, MEDLINE, and the Cochrane Library on diagnostic accuracy and clinical impact of commercially available rapid (results <3 hours) molecular diagnostics for respiratory viruses compared with conventional molecular tests were included. Sensitivity and specificity estimate of the most frequently described assays were pooled per assay; heterogeneity between studies was assessed by subgroup analyses for different study populations, different assays, viruses that were assessed, study designs, and studies of different quality. The reports included in the review had a median sample size of 95 patients and evaluated 13 commercial molecular rapid diagnostic tests. The most frequently studied tests were the Alere I Influenza A&B assay (14 reports), Cobas Liat Influenza A/B (5 reports), FilamArray (10 reports), Cepheid Xpert Flu Assay (9 reports), Simplexa Flu A/B & RSV kit (9 reports), and Verigene Respiratory Virus Plus test (5 reports).

The subgroup analysis between different assays showed that the Cobas Liat Influenza A/B assay was the most reliable The pooled sensitivity of all rapid molecular tests was 90.9% (95% CI, 88.7%-93.1%) and the pooled specificity was 96.1% (95% CI, 94.2%-97.9%) for the detection of either respiratory syncytial virus (RSV, n=1), influenza virus (n=29), RSV and influenza virus (n=19), or a viral panel including influenza virus and RSV (n=14). After screening, 15 clinical impact studies were included in order to understand the clinical effect and importance of these assays. However, the results of the impact studies overall were heterogeneous, making results inconclusive.

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All the studies unanimously found significantly decreased turnaround times. In the majority of studies, reduced length of hospital stay, increased appropriate use of oseltamivir in patients positive for the influenza virus, and a potential reduction in costs and additional radiographic imaging were observed. However, implementation of rapid molecular tests did not decrease the number of antibiotic prescriptions or the duration of antibiotic treatment.

Overall, the study authors concluded that overall, “results on [the] clinical impact of rapid diagnostic tests are conflicting, [however] there is high-quality evidence [in 2 specific areas:] rapid testing [for influenza] might decrease the length of hospital stay and might increase appropriate use of oseltamivir in influenza virus positive patients, without leading to adverse results.”

Reference

Vos LM, Bruning AHL, Reitsma JB, et al. Rapid molecular tests for influenza, respiratory syncytial virus, and other respiratory viruses: a systemic review of diagnostic accuracy and clinical impact studies [published online January 28, 2019]. Clin Infect Dis. doi:10.1093/cid/ciz056/5303789