archives@tulane.edu / Background: Prompt antiviral treatment of influenza virus infections can improve outcomes and reduce the likelihood of complications, particularly among children at high risk for complications. Recent, more stringent requirements for rapid influenza point-of-care test clinical sensitivity have implications for the impact and cost-effectiveness of outpatient influenza diagnosis and antiviral treatment. Objective: The objective of this research was to understand antiviral prescribing practices following and utilize these real-world probabilities to evaluate the cost effectiveness of rapid test-guided outpatient antiviral treatment in children. Methods: The analysis used data from patients presenting for outpatient care with influenza-like illness (ILI) collected through the Influenza Incidence and Surveillance Project (IISP). The first analysis used a retrospective case-control design to compare clinic, patient, and season characteristics that influenced the decision to prescribe influenza antiviral treatment following a negative rapid influenza detection test. The IISP data were then incorporated into cost-effectiveness analyses among high-risk and otherwise healthy children presenting for outpatient care with ILI. Results: The results from the first analysis demonstrated that clinicians prescribed influenza antivirals to 8.4% of all test-negative patients and that in age groups considered a proxy for high risk patients, prescribing was either less frequent among children aged <2 (aOR 0.4, 95% CI 0.3–0.6) or the same among adults aged ≥65 (aOR 0.9, 95% CI 0.7–1.3) compared with adults aged 18 to 64. The results from the antiviral cost-effectiveness analysis among healthy children showed that treatment guided by clinician judgement was cost saving compared to no treatment, but rapid testing produced the greatest benefit. Among high-risk children, test-guided treatment produced the greatest benefit and was cost effective. Results were sensitive to clinician diagnostic sensitivity, influenza prevalence and the probability a positive test or diagnosis would result in treatment. Conclusion: These studies indicated that clinical judgement continued to be used to prescribe antivirals for patients with suspected influenza, greatly impacting the associated costs of care. The decision to test for influenza should be contingent upon the results influencing treatment of the patient or high-risk contacts, or further costly diagnostic testing. / 1 / Ashley Fowlkes