528. Bacterial vs viral etiology of fever: a prospective study to estimate a host score’s potential to support ED physicians' etiologic accuracy

Abstract Background A host-protein score (BV) combining the circulating levels of TRAIL, IP-10 and CRP was developed for distinguishing bacterial from viral infection. BV’s potential to impact decision making at the emergency department (ED) was assessed by comparing BV to physician’s etiological suspicion. Methods Rosetta study participants, aged 3 months to 18 years with febrile respiratory tract infection or fever without source, were prospectively recruited in a tertiary care pediatric ED. The main eligibility criteria were symptoms for less than 7 days and immunocompetence. ED physician’s initial etiological suspicion (bacterial/viral/I don’t know) and degree of confidence (low/medium/high) were recorded in a questionnaire. BV was interpreted based on pre-defined score thresholds (viral/bacterial/equivocal); the results were not available to the physician. The etiologic reference standard was based on the diagnoses (bacterial/viral/indeterminate) of 3 independent pediatricians who were provided with all available patient data but blinded to BV. BV’s potential to impact the physician’s etiologic accuracy was estimated according to alignment between BV and etiological suspicion as filled in the questionnaire (assuming full adoption of BV by the physician). Results Among 348 patients recruited, 290 met eligibility criteria and had requisite serum sample (Figure 1A). Median age was 1.3 years (interquartile range 1.7), 37.5% were female. 211 patients had questionnaires filled. BV matched physician’s label and reference standard in 72% of the cases (151/211; Figure 1B); of these, 52% (78/151) were labeled by the physician with low/medium confidence, i.e., BV could reinforce the physician’s suspicion. In 12% of the cases (26/211) BV aligned with the reference standard but not with the physician’s suspicion, and therefore could correct the physician's etiologic diagnosis. BV did not align with the reference standard in 7% of the cases (14/211) and was equivocal in 9% of the cases (20/211). Overall, BV could potentially correct physician diagnosis and reduce error >2-fold, from 16.1% to 8.1%. Figure 1.Assessing the potential impact of BV on ED physician’s etiologic accuracy. (A) Reference standard outcomes and BV scores. (B) BV versus adjudication-based reference standard and ED physician etiologic suspicion. Cases with missing questionnaire were omitted; n=211. Conclusion BV has potential to aid the diagnostic process. Future studies are warranted to assess the real-world impact of BV on ED practice. Disclosures Meital Paz, MD, MeMed: employee Oded Scheuerman, MD, MeMed: Grant/Research Support Ron Berant, MD, GE: Advisor/Consultant.