Predictors of Influenza Diagnosis Among Patients With Laboratory-Confirmed Influenza

J Infect Dis. 2015 Nov 15;212(10):1604-12. doi: 10.1093/infdis/jiv264. Epub 2015 May 4.


Objective: This study was performed to determine predictors of clinical influenza diagnosis among patients with laboratory-confirmed influenza.

Methods: Prospective, laboratory-confirmed surveillance for influenza was conducted among patients of all ages who were hospitalized or presented to the emergency department with fever and respiratory symptoms during 2009-2013. We evaluated all enrolled persons who had influenza confirmed by viral culture and/or polymerase chain reaction and received any discharge diagnosis. The primary outcome, clinical influenza diagnosis, was defined as (1) a discharge diagnosis of influenza, (2) a prescription of neuraminidase inhibitor, or (3) a rapid test positive for influenza virus. Bivariate analyses and multiple logistic regression modeling were performed.

Results: Influenza was diagnosed for 29% of 504 enrolled patients with laboratory-confirmed influenza and for 56% of 236 patients with high-risk conditions. Overall, clinical influenza diagnosis was predicted by race/ethnicity, insurance status, year, being hospitalized, having high-risk conditions, and receiving no diagnosis of bacterial infection. Being diagnosed with a bacterial infection reduced the odds of receiving an influenza diagnosis by >3-fold for all patients and for patients with high-risk conditions.

Conclusions: Many influenza virus-positive patients, including those with high-risk conditions, do not receive a clinical diagnosis of influenza. The pattern of clinical diagnoses among influenza virus-positive patients suggests preferential consideration of bacterial diseases as a diagnosis.

Keywords: antiviral agents; clinical practice patterns; diagnosis; human; influenza.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Child
  • Child, Preschool
  • Clinical Medicine / methods*
  • Decision Support Techniques*
  • Female
  • Humans
  • Infant
  • Infant, Newborn
  • Influenza, Human / diagnosis*
  • Influenza, Human / pathology*
  • Male
  • Middle Aged
  • Practice Patterns, Physicians'*
  • Prospective Studies
  • Young Adult