Bedside diagnosis of influenzavirus infections in hospitalized children

Objective. For preventing nosocomial influenza infections and to facilitate prompt antiviral therapy, an accessible, rapid diagnostic method for influenzavirus is needed. We evaluated the performance of a lateral-flow immunoassay (QuickVue Influenza Test) completed at the bedside of hospitalized children during the influenza season. Methods. All children who were evaluated at a large teaching hospital during the 1999 to 2000 influenza season were eligible if they were 1) younger than 19 years and hospitalized with respiratory symptoms or 2) younger than 3 years and hospitalized with fever. Each study child had 2 nasal swabs obtained-1 for influenzavirus culture and polymerase chain reaction (PCR) and the other for the QuickVue Influenza Test. The performance of the rapid diagnostic test was compared with the results of culture or PCR for influenza A or B. Results. Of 303 eligible children, 233 (77%) were enrolled. In this population, 19 children had culture- and/or PCR-confirmed influenza A infection, prevalence of 8%. The QuickVue Influenza Test had a sensitivity of 74%, specificity of 98%, positive predictive value of 74%, and negative predictive value of 98%. Conclusions. Among children hospitalized with fever/ respiratory symptoms during the influenza season, negative bedside QuickVue Influenza Tests indicated very low likelihood of influenza infection, whereas positive tests greatly increased the probability of influenza-associated illness.