Risk factors for hospitalization among children with influenza B infection.

Data regarding risk factors for hospitalization among children with influenza B infection are limited. We conducted a retrospective study of 184 children with influenza B infection during October 2011 - September 2012 seen at Bamrasnaradura Infectious Diseases Institute, Thailand; clinical and laboratory data were compared between hospitalized and outpatient children. The numbers of hospitalized and outpatient children were 65 (35%) and 119 (65%), respectively. Most children (> 80%) were aged > or = 5 years. The median time from onset of symptoms to starting oseltamivir treatment was significantly longer among hospitalized than outpatient children (3 days vs 2 days, p < 0.05). The significantly more hospitalized children received antibiotics than outpatient children (43% vs 7%, p < 0.05). Complications were more common among hospitalized children than outpatient children (37% vs 2%, p < 0.05). Pneumonia and rhinosinusitis were significantly more common among hospitalized children than outpatient children (p < 0.05). Direct contact history, history of receiving an influenza vaccine, history of a previous influenza infection, body temperature, respiratory symptoms, gastrointestinal symptoms, headache and laboratory findings were not significantly different between the two groups (p > 0.05). In conclusion, delay initiation of antiviral therapy and medical complications (pneumonia and rhinosinusitis) were more common among hospitalized children with influenza B than outpatient children with influenza B in the studied population.