The impact of rapid molecular diagnostic testing for respiratory viruses on outcomes for emergency department patients

Abstract

Objective To determine whether rapid polymerase chain reaction ( PCR ) testing for influenza and respiratory syncytial viruses ( RSV ) in emergency departments ( ED s) is associated with better patient and laboratory outcomes than standard multiplex PCR testing. Design, setting A before‐and‐after study in four metropolitan ED s in New South Wales. Participants 1491 consecutive patients tested by standard multiplex PCR during July–December 2016, and 2250 tested by rapid PCR during July–December 2017. Main outcome measures Hospital admissions; ED length of stay ( LOS ); test turnaround time; patient receiving test result before leaving the ED ; ordering of other laboratory tests. Results Compared with those tested by standard PCR , fewer patients tested by rapid PCR were admitted to hospital (73.3% v 77.7%; P < 0.001) and more received their test results before leaving the ED (67.4% v 1.3%; P < 0.001); the median test turnaround time was also shorter (2.4 h [ IQR , 1.6–3.9 h] v 26.7 h [ IQR , 21.2–37.8 h]). The proportion of patients admitted to hospital was also lower in the rapid PCR group for both children under 18 (50.6% v 66.6%; P < 0.001) and patients over 60 years of age (84.3% v 91.8%; P < 0.001). Significantly fewer blood culture, blood gas, sputum culture, and respiratory bacterial and viral serology tests were ordered for patients tested by rapid PCR . ED LOS was similar for the rapid (7.4 h; IQR , 5.0–12.9 h) and standard PCR groups (6.5 h; IQR , 4.2–11.9 h; P = 0.27). Conclusion Rapid PCR testing of ED patients for influenza virus and RSV was associated with better outcomes on a range of indicators, suggesting benefits for patients and the health care system. A formal cost–benefit analysis should be undertaken.

The impact of rapid molecular diagnostic testing for respiratory viruses on outcomes for emergency department patients

“…The potential impact of the differences in the prevalence and severity of influenza during the two study periods was adequately acknowledged in our article as a limitation. The objective of our study was to determine the association between the use of rapid polymerase chain reaction (PCR) for respiratory viruses in emergency departments and patient and laboratory outcomes . It is important to remember that, consistent with previous similar studies, our study evaluated the correlation (association) between rapid PCR use and outcomes (eg, hospital admission) and did not claim any cause‐and‐effect relationship.…”

“…In reply : Katelaris and colleagues raise concerns that uncontrolled before‐and‐after studies are vulnerable to bias and that other factors (eg, the severity of influenza) may have confounded our findings . I agree that uncontrolled before‐and‐after studies, being observational studies, are generally prone to different types of bias and that other residual (unmeasured) factors may have confounded our study outcomes …”

“…The causal inferences can only reliably be drawn using randomised controlled trials. As noted in our article, because of its inherent design limitations, our study could not fully account for all possible confounders or temporal trends in the severity and prevalence of influenza …”

Automation and Molecular Diagnostics: A New Era in Clinical Microbiology

“…5 Another example is the introduction of PCRbased testing for influenza A and B. 7 These influenza tests give very rapid results to the ordering physician so that patients may be started on appropriate antiviral therapies while also providing valuable epidemiological information about the prevalence of the virus during yearly flu seasons.…”

The impact of rapid molecular diagnostic testing for respiratory viruses on outcomes for emergency department patients

“…To the Editor : Uncontrolled before‐and‐after studies are highly prone to bias. Wabe and colleagues report on the impact of rapid influenza testing on outcomes for emergency department (ED) patients . They compared outcomes across four hospitals between the 2016 influenza season, when standard testing was used, and 2017, when rapid testing was used.…”