Predictors of unfavorable outcome in children hospitalized with influenza and differences in clinical presentation among serotypes

Apart from age and underlying disease, predictors of adverse outcome in children hospitalized with influenza are poorly understood.Our goal is to determine clinical and laboratory predictors that help identify children at increased risk for an unfavorable course and identify differences in clinical presentation between serotypes.A retrospective, observational cohort study conducted at the Rambam Healthcare Campus in Haifa. We analyzed data from electronic records of children18 years with influenza A or B infection hospitalized between 2009 and 2020. Multivariate regression analyses were used to identify predictors of unfavorable outcome, defined as mortality, ICU admission, intubation, prolonged length of stay, or bacterial coinfection.A total of 1077 children were included, of whom 54% were male. The median age was 2.5 years. Influenza A was detected in 797 (74%) and influenza B in 286 (26%) of the cases. Children with influenza A were younger (OR 2.51, 95%CI 1.90-3.33), more likely to have oxygen desaturation90% (OR 2.44, 95%CI 1.23-4.83) and an elevated CRP5 mg/dL on admission (OR 2.67, 95% CI 1.63-4.37). In multivariate analyses, oxygen desaturation90% and CRP5 mg/dL at admission had an 11.1 and 4-fold increased risk of unfavorable outcome, respectively, in addition to a 3.1 and 1.6-fold increased risk in the presence of underlying condition or influenza A serotype infection, respectively.Data available on admission can help identify children hospitalized with influenza who are at increased risk for complications and unfavorable outcome, encouraging aggressive treatment and care.