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Derivation and Validation of a Clinical Decision Guideline for Influenza Testing in Four U.S. Emergency Departments.

STUDY OBJECTIVE
Accurate diagnosis of influenza is essential for appropriate antiviral treatment in accordance with Centers for Disease Control and Prevention (CDC) guidelines. However, no clear guidance exists on whom should be tested. We sought to develop a clinical decision guideline (CDG) to inform influenza testing decisions for adult emergency department (ED) patients deemed appropriate for antiviral treatment by CDC guidelines.


METHODS
Prospective cohort study was performed at four U.S. EDs. From November 2013 to April 2014 we enrolled adult ED patients with fever or respiratory symptoms, who met criteria for antiviral treatment per 2013 CDC guidelines. All patients were tested for influenza using PCR. Data were randomly split into derivation (80%) and validation (20%) datasets. A discrete set of independent variables was selected by logistic regression using the derivation set to create a scoring system, with a target sensitivity of at least 90%. The derived CDG was then validated.


RESULTS
Of 1941 enrolled participants, 183 (9.4%) had influenza. The derived CDG included new or increased cough (2 points), headache (1 point), subjective fever (1 point), and triage temperature >100.4°C (1 point), with a score of ≥3 indicating influenza testing was warranted. The CDG had a sensitivity and specificity of 94.1% and 36.6% in the derivation set, and 91.5% and 34.6% in the validation set, respectively.


CONCLUSION
A CDG with high sensitivity was derived and validated. Incorporation into practice could standardize testing for high-risk patients in adult EDs during influenza seasons, potentially improving diagnosis and treatment.


CLINICAL TRIAL REGISTRATION
NCT01947049.