The Association Between Obesity and Severe Influenza Outcomes in Pediatric Populations

Background: Obesity can result in chronic inflammation impairing immune responses. As a result of immune dysregulation, adults with obesity have been shown to have more severe sequelae of influenza infections, including longer lengths of hospital stays (LOS) and increased mortality. However, less is known about pediatric obesity and its effect on disease immune response. The primary aim of this study was to determine if obesity was associated with increased influenza severity in a large cohort of hospitalized children.

Methods: A retrospective cross-sectional inpatient study using the Healthcare Cost and Utilization Project Kids’ Inpatient Database (HCUP-KID) was performed to evaluate the association between obesity and more severe influenza outcomes. All available HCUP-KID years were investigated, and subjects aged 1-20 years with an inpatient diagnosis of influenza were included. Diagnoses were defined using ICD-9 or ICD-10 codes. Multivariable linear and logistic regression were used to evaluate for associations between obesity or overweight status and LOS and markers of disease severity. Findings were adjusted for demographic effects such as race, age, gender, and socioeconomic status.

Results: Subjects (n=195,103) were categorized as neither overweight nor obese (n=192,788), overweight (n=162), or obese (n=2154). Age had a statistically significant correlation with weight status (p < 0.0001), and a diagnosis of obesity was associated with a more prolonged course of influenza, as determined through length of hospital stay (median 2.797 days vs. 1.830 days, p < 0.0001). Additionally, obesity was associated with a two-fold increase in markers of severe disease such as mortality, sepsis, and the need for pulmonary procedures. Meanwhile, associations between overweight status and severity were not significant.

Conclusion: In this cohort, obesity was associated with a prolonged course of influenza and a two-fold increase in mortality risk. Despite different chronic disease burdens, children exhibited increased risk for severe influenza disease in the context of obesity, not unlike adults. Next steps include investigating the relationship between pediatric obesity and other markers of influenza severity, with eventual expansions into additional respiratory infections.