Evaluation of Psychometric Testing Properties of Severity Symptom Grading Scale of Influenza Infection: Flu-PRO Stage III

There is no standardized method for evaluating the symptoms of influenza. A standardized instrument for measuring influenza symptoms, with appropriate scientifically derived content and construct validity would have value for public health in terms of use as a validated outcome measure in interventions to treat or prevent influenza. The instrument also could serve as part of an overall measure of severity of illness in influenza. Previous efforts in participant reported outcomes (PRO) for influenza (i.e. Flu-PRO Stage I and Stage II) focused on the elicitation and evaluation of items for inclusion in the instrument. The overarching objective of this protocol - Flu-PRO Stage III - is to conduct instrument validation to evaluate item properties and, if need be, reduce the number of items, and quantitatively validate the performance of the final measure.