Impact of clinical guidance and rapid molecular pathogen detection on evaluation and outcomes of febrile or hypothermic infants.

To quantify the impact of clinical guidance and rapid respiratory and meningitis/encephalitis multiplex polymerase chain reaction (mPCR) testing on the management of infants. Before-and-after intervention study. Tertiary-care children's hospital. Infants ≤90 days old presenting with fever or hypothermia to the emergency department (ED). The study spanned 3 periods: period 1, January 1, 2011, through December 31, 2014; period 2, January 1, 2015, through April 30, 2018; and period 3, May 1, 2018, through June 15, 2019. During period 1, no standardized clinical guideline had been established and no rapid pathogen testing was available. During period 2, a clinical guideline was implemented, but no rapid testing was available. During period 3, a guideline was in effect, plus mPCR testing using the BioFire FilmArray respiratory panel 2 (RP 2) and the meningitis encephalitis panel (MEP). Outcomes included antimicrobial and ancillary test utilization, length of stay (LOS), admission rate, 30-day mortality. Outcomes were compared across periods using Kruskal-Wallis and Pearson tests and interrupted time series analysis. Overall 5,317 patients were included: 2,514 in period 1, 2,082 in period 2, and 721 in period 3. Over the entire study period, we detected reductions in the use of chest radiographs, lumbar punctures, LOS, and median antibiotic duration. After adjusting for temporal trends, we observed that the introduction of the guideline was associated with reductions in ancillary tests and lumbar punctures. Use of mPCR testing with the febrile infant clinical guideline was associated with additional reductions in ancillary testing for all patients and a higher proportion of infants 29-60 days old being managed without antibiotics. Use of mPCR testing plus a guideline for young infant evaluation in the emergency department was associated with less antimicrobial and ancillary test utilization compared to the use of a guideline alone.