Impact of Rapid Molecular Diagnostic Testing of Respiratory Viruses on Outcomes of Adults Hospitalized with Respiratory Illness: a Multicenter Quasi-experimental Study

A standard multiplex PCR offers comprehensive testing for respiratory viruses. However, it has traditionally been performed in a referral laboratory with a lengthy turnaround time, which can reduce patient flow through the hospital. We aimed to determine whether the introduction of a rapid PCR, but with limited targets (Cepheid Xpert Flu/RSV XC), was associated with improved outcomes for adults hospitalized with respiratory illness. A controlled quasi-experimental study was conducted across three hospitals in New South Wales, Australia. Intervention groups received standard multiplex PCR during the preimplementation, July to December 2016 (n = 953), and rapid PCR during the postimplementation, July to December 2017 (n = 1,209). Control groups (preimplementation, n = 937, and postimplementation, n = 1,102) were randomly selected from adults hospitalized with respiratory illness during the same periods. The outcomes were hospital length of stay (LOS) and microbiology test utilization (blood culture, urine culture, sputum culture, and respiratory bacterial and virus serologies). The introduction of rapid PCR was associated with a nonsignificant 8.9-h reduction in median LOS (95% confidence interval [CI], -21.5 h to 3.7 h; P= 0.17) for all patients and a significant 21.5-h reduction in median LOS (95% CI, -36.8 h to -6.2 h; P< 0.01) among patients with positive test results in an adjusted difference-in-differences analysis. For patients receiving test results before disposition, rapid PCR use was associated with a significant reduction in LOS, irrespective of test results. Compared with standard PCR testing, rapid PCR use was significantly associated with fewer blood culture (adjusted odds ratio (aOR), 0.67; 95% CI, 0.5 to 0.82; P< 0.001), sputum culture (aOR, 0.56; 95% CI, 0.47 to 0.68, P< 0.001), bacterial serology (aOR, 0.44; 95% CI, 0.35 to 0.55, P< 0.001) and viral serology (aOR, 0.42; 95% CI, 0.33 to 0.53, P< 0.001) tests, but not with fewer urine culture tests (aOR, 0.94; 95% CI, 0.78 to 1.12, P = 0.48). Rapid PCR testing of adults hospitalized with respiratory illnesses can deliver benefits to patients and reduce resource utilization. Future research should consider a formal economic analysis and assess its potential impacts on clinical decision making.