Application of the rapid influenza testing during 2007-2008 flu season in Beijing city

Abstract

Objective To analyze the application value of the rapid testing for influenza during 2007-2008 flu season at fever clinic in Beijing Chaoyang hospital Methods 500 patients with diagnosis of influenza-like illness were prospectively enrolled. Pharyngeal swabs were collected for influenza viral culture and rapid testing for influenza. Demographic characteristics, age, symptoms, lab tests, symptom recovery time and medical expense were also collected. The sensitivity, specificity, positive predictive value and negative predictive value for rapid testing were analyzed. Results A total of 500 patients were enrolled between Dec 2007 and March 2008. Among them 498 cases were used for analysis. Influenza B was most common by virus culture methed(n=208,41.8%) ,followed by influenza A (n=51,10.2%). The average age was 35, and the ratio of male to female was 1.47:1. Compared with the group of positive culture, patients with influenza were more likely to get cough, sore throat, and nasal congestion (t=13.728, 4.014and 4.720,P<0.001 or 0.05, respectively). A total of 260 cases were subjected to rapid testing, Among them 18 cases were influenza A positive and 132 cases were influenza B positive. The rapid testing had a sensitivity of 77.1 % and a specificity of 70.1%. The positive predictive value was 78.6% and the negative predictive value was 68.2%. The rapid testing had enhanced the proportion of anti-viral treatment from 0 to 26% and reduced the proportion of antibiotic use from 63.4% to 20. 7%. Conclusions Influenza B is the most predominant pathogen during 2007-2008 flu season among patients with influenza-like illness in Beijing. The rapid testing with high sensitivity and specificity provides guidance on clinical practice. Key words: Influenza virus A,B; Virus cultivation