Determination of Clinical and Demographic Predictors of Laboratory-confirmed Influenza with Subtype Analysis.

摘要

Given the mediocre performances of many rapid influenza tests, clinical diagnosis has reemerged in importance. Methods: Respiratory specimens and demographic and clinical data were obtained from 3- to 80-year-old subjects with influenza-like illness (ILI) from November 2007 to April 2008. Reverse-transcriptase polymerase chain reaction testing and viral culture for influenza A and B with subtyping were performed on all specimens. Associations between influenza and demographic/clinical parameters were assessed by logistic regression. The predictive values of multiple combinations of identified clinical predictors, including the Centers for Disease Control and Prevention (CDC) ILI case definition, were determined. Of 789 subjects, 220 (27.9%) had laboratory-confirmed influenza. Independent predictors of influenza included fever, cough, acute onset, body aches, and vaccination status among 6- to 49-year olds; only vaccination among 3- to 5-year-olds; only fever among 50- to 80-year-olds. Various clinical case definitions were highly sensitive (100.0%) or specific (98.6%), but none had both parameters over 60%, though many performed better than the CDC ILI case definition. Influenza predictors differ across age groups. No combination of clinical/demographic predictors serves as a reliable case definition. A standardized case definition combined with a point-of-care laboratory test may be the optimal rapid diagnostic strategy available.