# P-527. Impact of Obesity and adipokine levels in Young Children with Respiratory Syncytial Virus (RSV) Infection

## TL;DR

This study finds that obesity in young children is linked to more severe Respiratory Syncytial Virus (RSV) infections and higher clinical severity scores.

## Contribution

The study is one of the first to show that obesity, not just undernutrition, is associated with worse RSV outcomes in young children.

## Key findings

- Obese infants with RSV required more supplemental oxygen and had higher PICU admission rates.
- Obese RSV-infected children had higher leptin concentrations and greater leptin/adiponectin ratios.
- Overweight and obese children showed greater disease severity compared to normal-weight children.

## Abstract

Obesity has been linked to worse clinical outcomes in children infected with influenza and SARS-CoV-2. The limited number of studies examining the relationship between weight and disease severity in young children with RSV infection have primarily focused on the role of undernutrition.Figure 1.Nutritional status among infants with mild (outpatients) and severe (inpatients) RSV infection and healthy controlsX axis includes the three clinical groups, healthy controls, children with mild RSV infection– outpatients; OP– and children with severe RSV infection (inpatients- IP0) that were stratified according to their nutritional status (gray: normal weight, light pink: overweight, dark pink: obese). Y axis represents the proportion of patients included in each category.Table 1.Demographic, clinical characteristics, and outcomes of children with RSV infection according to their nutritional status.CDSS: clinical disease severity score. Data expressed as median [25-75% IQR] for continuous variables and as numbers (%) for categorical data. Analyses by Fisher or Chi-square, and Kruskal-Wallis test with Dunn’s multiple comparisons test.

Nutritional status among infants with mild (outpatients) and severe (inpatients) RSV infection and healthy controls

X axis includes the three clinical groups, healthy controls, children with mild RSV infection– outpatients; OP– and children with severe RSV infection (inpatients- IP0) that were stratified according to their nutritional status (gray: normal weight, light pink: overweight, dark pink: obese). Y axis represents the proportion of patients included in each category.

Demographic, clinical characteristics, and outcomes of children with RSV infection according to their nutritional status.

CDSS: clinical disease severity score. Data expressed as median [25-75% IQR] for continuous variables and as numbers (%) for categorical data. Analyses by Fisher or Chi-square, and Kruskal-Wallis test with Dunn’s multiple comparisons test.

Prospective observational study in otherwise healthy children < 2 years hospitalized or managed as outpatients with RSV infection at a large US Pediatric Hospital between 2015-21. Healthy control infants were enrolled in parallel. Nutritional status was assessed using the WHO Z-scores for weight and length according to age. Normal weight (eutrophic) was defined as −0.9 to 0.9 SD, overweight as 1.0 to ≤2.0 SD, and obesity as >2 SD. Overnutrition included the combination of overweight and obesity. Serum leptin and adiponectin concentrations were measured by ELISA, as regulatory molecules related to metabolism and weight, and correlated with clinical outcomes.

We enrolled 188 children with RSV infection (median [IQR] age: 4.2 [2.0-8.6] months), and 50 healthy controls (7.8 [5.3-13.3] months). Obesity was found in 7% of RSV-outpatient infants, 15% of RSV-inpatients and 8% of controls; p=0.03; Fig 1. Within infants with RSV infection, those with overnutrition required supplemental oxygen more frequently (83% vs. 62%; p< 0.01) and had higher rates of PICU admission (60% vs. 32%; p=0.001) compared to those with normal weight. Moreover RSV-infected infants with obesity had higher clinical disease severity scores, greater need for PICU admission, longer hospitalizations, higher leptin concentrations, and greater leptin/adiponectin ratios compared with eutrophic and overweight RSV-infected children (p< 0.01); Table 1. There were no differences in C-reactive protein concentrations and RSV loads between normal vs overweighted children.

Excess nutrition in infants and young children assessed by Z-scores, showed differences in leptin/adiponectin concentrations, and was associated with greater RSV disease severity in a high-resourced country. This study underscores the importance of monitoring not only undernutrition, but overweight and obesity in young children with RSV infection.

Cristina Tomatis Souverbielle, MD, Merck inc: Research support isp Octavio Ramilo, MD, Merck: Advisor/Consultant|Merck: Grant/Research Support|Merck: Honoraria|Moderna: Advisor/Consultant|Pfizer: Advisor/Consultant|Pfizer: Honoraria|Sanofi: Advisor/Consultant Asuncion Mejias, MD, PhD, MsCS, Enanta: Advisor/Consultant|Merck: Grant/Research Support|Moderna: Advisor/Consultant|Pfizer: Advisor/Consultant|Sanofi-Pasteur: Advisor/Consultant