Abstract
BACKGROUND: Diagnosing influenza and respiratory syncytial virus (RSV) with conventional multiplex respiratory viral polymerase chain reaction (PCR) takes 24-72 hours compared with under two hours for recently available rapid PCR tests. We investigated the impact of rapid diagnosis of acute respiratory viral infection on admission odds from the emergency department (ED) and acute inpatient length of stay (LOS), as well as concordance between the rapid and conventional PCR tests used at our institution. METHODS: Single-center retrospective cohort study of patients presenting to the ED with influenza-like illness. We compared the odds of admission and acute LOS in patients investigated with rapid PCR, those investigated with conventional PCR, and those investigated with both tests. Multivariable logistic regression was used to assess the odds of admission, while linear regression was used to assess LOS. RESULTS: There was no significant change in the odds of admission among patients who received the rapid PCR compared to conventional PCR (odds ratio: 1.01, 95% confidence interval [CI]: 0.50-2.02; p = 0.96). There was also no significant difference in LOS of admitted patients who received rapid PCR testing (regression coefficient: -0.32, 95% CI: -1.75 to 1.12; p = 0.66). The rapid PCR test used at our institution yielded fully concordant results with conventional PCR testing. CONCLUSIONS: Rapid PCR testing is as sensitive as conventional PCR testing for the diagnosis of influenza and RSV but is neither associated with a significant impact on admission nor inpatient LOS. Further research is needed to assess the impact of rapid testing on isolation room use.